Miracle-dz/UniFAR-FTUs huggingface dataset:
A Strategy to Reduce the Count of Moment Conditions in Panel Data GMM

The problem of instrument proliferation and its consequences (overfitting of endogenous variables, bias of estimates, weakening of Sargan/Hansen test) are well known. The literature provides little guidance on how many instruments is too many. It is common practice to report the instrument count and to test the sensitivity of results to the use of more or fewer instruments. Strategies to alleviate the instrument proliferation problem are the lag-depth truncation and/or the collapse of the instrument set (the latter being an horizontal squeezing of the instrument matrix). However, such strategies involve either a certain degree of arbitrariness (based on the ability and the experience of the researcher) or of trust in the restrictions implicitly imposed (and hence untestable) on the instrument matrix. The aim of the paper is to introduce a new strategy to reduce the instrument count. The technique we propose is statistically founded and purely datadriven and, as such, it can be considered a sort of benchmark solution to the problem of instrument proliferation. We apply the principal component analysis (PCA) on the instrument matrix and exploit the PCA scores as the instrument set for the panel generalized method-of-moments (GMM) estimation. Through extensive Monte Carlo simulations, under alternative characteristics of persistence of the endogenous variables, we compare the performance of the Difference GMM, Level and System GMM estimators when lag truncation, collapsing and our principal component-based IV reduction (PCIVR henceforth) are applied to the instrument set. The same comparison has been carried out with two empirical applications on real data: the first replicates the estimates of Blundell and Bond [1998]; the second exploits a new and large panel data-set in order to assess the role of tangible and intangible capital on productivity. Results show that PCIVR is a promising strategy of instrument reduction.
1 Evaluating the Importance of Human Realistic Walking Simulation for Creating Realistic Characters

The goal of this work is to create human-realistic simulation for virtual characters’ walking behaviors, in particular, their route selection, obstacle avoidance and pursue behaviors, and evaluate whether such simulation makes the characters’ behaviors more believable. Though various algorithms exist for path finding and steering behaviors, the simulated behaviors are typically not created based on models of human behaviors. This work presents a computational model of walking simulation, which is based on the ecological theories of psychology and using parameters extracted from real human data. The system has been fully implemented. This paper presents the algorithms in detail, followed by preliminary results, discussion, and proposed future work on evaluating the models. Keywords--Walking Simulation, Virtual Character, Dynamic System.
The Psychological Actions and Entrepreneurial Success : An Action Theory Approach 1

This chapter starts with a strong assumption: Entrepreneurs’ actions are important and should be a starting point for theorizing in entrepreneurship (cf. also McCullen & Shephard, 2006). I am well aware that not all entrepreneurship theorists share this assumption. Most importantly, ecological theories have left out actions from their theories (Aldrich, 1999). This is surprising for an evolutionary approach because entrepreneurial actions are as important to entrepreneurial outcomes as sexual behavior is to procreation and, therefore, survival of genes and population of genes (Dawkins, 1976). Whether or not an organization occupies a successful niche or whether or not it introduced an innovation is the result of actions and not a purely accidental process. Starting one’s business in a market niche and defending the niche is an active process and not passive adaptation. Such an active approach is slowly accepted in entrepreneurship research, as scholars take more seriously that there can be effective and non-effective actions vis-à-vis the market (McMullen & Shephard, 2006; Sarasvathy, 2001). Most actions are geared towards the environment and take into account environmental conditions. However, the most important feature of entrepreneurial action is not that it is well adjusted to environmental conditions (this is true of behavior that reacts to environmental stimuli and is guided by the stimuli) but that it changes the environment.
DEVELOPMENT OF A MATLAB GRAPHICAL USER INTERFACE FOR THE MULTI-TENSOR ANALYSIS OF DIFFUSION MAGNETIC RESONANCE IMAGING

The estimation of diffusion tensors in diffusion tensor imaging (DTI) is based on the assumption that each voxel is homogeneous and can be represented by a single or multi tensor. As a result, estimation errors arise particularly in voxels with partial voluming of white matter or gray matter with cerebrospinal fluid (CSF) and voxels where fibers cross. This paper presents a tool for analysis of DTI called MultiTensor which was developed in Matlab language in order to help DTI researchers by making the analysis more easier and faster. The user enters the number of slices, bvalues, the gradient directions , the number of excitations. Then the program begin by preparing the Dicom file, estimates both single and two tensor, the anisotropy indices and the error in estimation. Keywords–Diffusion Imaging, GUI, multi-tensor , magnetic resonance Imaging.
An Efficient Lattice-based Distributed IBE

This paper improves the lattice-based secret sharing method presented by Bansarkhani and Meziani and combines the method with the IBE based on the standard LWE problem constructing an efficient lattice-based distributed decryption IBE. Our construction avoids the weakness in the traditional method like Lagrange interpolation, Blakley’s space geometry method or Chinese remainder theorem method. Through theoretical analysis, compared with the bilinear pairing based distributed IBE, our scheme refrains from the complex pairing operation and has less calculation cost. A proof of security holds in the standard model.
Factors That Have An Influence On Time Series

In the last years the development in the processing of SAR persistent scatterers interferometry (PSI) data has allowed an improvement in time series precision, also with the data processed on regional scale. It is possible now to study the behaviour in the time of different type of natural process. The more recent data are elaborated also with non-linear models and this allows, even if with many restrictions and problems, to study also the temporal variation in the evolution of a process. In this work we have analyzed the time series (TS) of ERS (1992-2001) and RADARSAT (2003-2010) data elaborated with SqueeSARTM processing over three studied areas in NW Italy (Western Piemonte, Province of Pavia and Province of Imperia). We compared the time series with other monitoring data in order to validate them and to find the positive and negative aspects in the detection of natural processes. At the same time the TS were used to understand the kinematics of some geological processes.
Audit Exemption and the Demand for Voluntary Audit: A Comparative Study of the UK and Denmark

This study investigates the sufficiency of turnover as a surrogate for demand for voluntary audit and compares the determinants in the UK and Denmark. Empirical data for the study were drawn from government surveys of the directors of small private companies in both countries, which were based on the same research instrument, Bivariate tests support the hypothesised effects of turnover and a range of firm-specific factors suggested by economic rationality and agency theory. The main contribution of the study is the finding that turnover alone is not a sufficient surrogate for the costs and benefits of audit. The main predictors are turnover and a slightly different combination of management and agency factors in each country. The study provides a model that can be tested in other jurisdictions and its findings should be of interest to the accountancy profession and national regulators planning to introduce or revise audit exemption for small companies.
Quantitative Analysis of Micro-Structure in Meat Emulsions from Grating-Based Multimodal X-Ray Tomography

Using novel X-ray techniques, based on grating-interferometry, new imaging modalities can be obtained simultaneously with absorption computed tomography (CT). These modalities, called phase contrast and dark field imaging, measure the electron density and the diffusion length of the sample. Enhanced contrast capabilities of this X-ray technique makes studies on materials with similar attenuation properties possible. In this paper the focus is set on processing grating-based X-ray tomograms of meat emulsions to quantitatively measure micro-structural changes due to heat treatment. The emulsion samples were imaged both in a raw and cooked state. Additionally, different fat types were used in the emulsions in order to compare micro-structural differences when either pork fat or sunflower oil was used. From the reconstructed tomograms the different ingredients in the emulsions were segmented using a multivariate segmentation method. From this, a quantitative analysis was performed between the different samples, determining properties such as percentage object volumes and cooking loss. Additionally, the porosity, degree of anisotropy and average structure thickness of the protein networks were determined. Analyzing the multivariate dataset instead of the single univariate absorption modality gave superior segmentation results. The quantitative analysis of the micro-structure gives insight to how both heat treatment, and the use of different lipid types, affect the final protein network.
Effect of point defects on the optical and transport properties of mos2 and ws2

Introduction. The mobility of current single-layer crystals of transition metal dichalcogenides (TMD) is highly dependent on the screening environment and is limited by the presence of defects in the samples. The existence of defects in the chemical and structural composition of those materials can influence their optical and transport properties, as revealed by recent experimental results. A broad peak at ∼700 nm (∼1.77 eV) in the optical spectrum of bilayer MoS2 has been associated to impurities [1], whereas the mobility of multilayer samples has been shown to highly depend on the substrate and dielectric effects [2]. Vacancy defects in the crystal, which can be created by means of thermal annealing and α-particle [3] or electron beam irradiation [4,5], trap free charge carriers and localize excitons, leading to new peaks in the photoluminescence spectra [3]. Recent experiments [5] show that the density of sulfur vacancies in MoS2 is of the order of 10 13 cm −2 , corresponding to an average defect distance of about 1.7 nm. The existence of line defects, which separate patches or islands where the layer direction is opposite to its surrounding, can lead to changes in the carrier mobility [6], and the importance of short-range disorder has been proposed as the main limitation for the mobility of chemical vapor deposition grown single-layer MoS2 [7,8]. Therefore, it is necessary to understand the effect of impurities in the optical and transport properties of TMD, as a first step to exploit the controlled creation of defects as a route to manipulate their electronic properties. There are several theoretical works which have studied this problem usingabinitio methods [6,9–15]. However, the simulation of realistic disordered samples of TMD with a random distribution of defects is extremely expensive computationally for density functional theory methods, since they require a very large unit cell in the calculation. In this Rapid Communication we follow an alternative route and perform a systematic study of the density of states, optical and dc conductivities of single layers of MoS2 and WS2 in the presence of point defects, by means of a real space tight-binding (TB) model for large systems,
Symmetric supermodes in cyclic multicore fibers

Nearest-neighbor coupled-mode theory is a powerful framework to describe electromagnetic-wave propagation in multicore fibers, but it lacks precision as the separation between cores decreases. We use abstract symmetries to study a ring of evenly distributed identical cores around a central core, a common configuration used in telecommunications and sensing. We find its normal modes and their effective propagation constants while including the effect of all high-order inter-core couplings. Finite element simulations support our results to good agreement. Only two of these effective modes involve fields in all the cores. These two modes display opposite-sign phase configurations between the fields in the external cores and the central core. These two modes still appear in the limit where the external cores become a continuous ring. Our results might help improve predictions for crosstalk in telecommunications or precision in sensing applications.
Thomson, M. and Infield, D.G. (2007) Network power flow analysis for a high penetration of distributed generation. IEEE Transactions on Power

Increasing numbers of very small generators are being connected to electricity distribution systems around the world. Examples include photovoltaics (PV) and gas-fired domestic-scale combined heat and power (micro-CHP) systems, with electrical outputs in the region of 1 to 2 kW. These generators are normally installed within consumers premises and connected to the domestic electricity supply network (230 V single-phase in Europe, 120 V in North America). There is a growing need to understand and quantify the technical impact that high penetrations of such generators may have on the operation of distribution systems. This paper presents an approach to analysing this impact together with results indicating that considerable penetrations of micro-generation can be accommodated in a typical distribution system. Index Terms Distributed generation, Distribution networks, Micro-CHP, Micro-generation, Photovoltaics, PV, Cogeneration.
Flavonoids analysis of four Vicia species of Narbonensis complex in two different vegetative phases

Abstract A qualitative analysis of flavonoids has been carried out for Vicia eristalioides Maxt. , V. kalakhensis Khatt. , Maxt. and Bisby, V. narbonensis L. and V. galilaea Plitm. et Zoh in two different vegetative phases. Free aglycones were consistently absent and there was no evidence of flavone glycosides, whereas kaempferol and quercetin glycosides were present in different amounts, according to the species. The flavonoid patterns of the four species were compared and differences were present among them and also within the same species during the two vegetative phases. The results indicate that flavonoid data may be used in the study of the organisation and evolution in Narbonensis complex.
An efficient algorithm for distribution network restoration

This paper proposes an efficient and computationally fast solution algorithm for distribution system restoration based on a mathematical programming approach. The computation time is improved greatly by dividing the problem into two stages and incorporating restoration strategies, which are derived from on operator's knowledge and experience. It is shown from simulation results that this method is able to obtain an optimal target configuration in all cases. In addition, the computation time has been reduced to within 30% of the authors' previous method.
DETECTION OF REST-FRAME OPTICAL LINES FROM X-SHOOTER SPECTROSCOPY OF WEAK EMISSION-LINE QUASARS

Over the past 15 yr, examples of exotic radio-quiet quasars with intrinsically weak or absent broad emission line regions (BELRs) have emerged from large-scale spectroscopic sky surveys. Here, we present spectroscopy of seven such weak emission line quasars (WLQs) at moderate redshifts (z = 1.4–1.7) using the X-shooter spectrograph, which provides simultaneous optical and near-infrared spectroscopy covering the rest-frame ultraviolet (UV) through optical. These new observations effectively double the number of WLQs with spectroscopy in the optical rest-frame, and they allow us to compare the strengths of (weak) high-ionization emission lines (e.g., C iv) to low-ionization lines (e.g., Mg ii, Hβ, Hα) in individual objects. We detect broad Hβ and Hα emission in all objects, and these lines are generally toward the weaker end of the distribution expected for typical quasars (e.g., Hβ has rest-frame equivalent widths ranging from 15–40 Å). However, these low-ionization lines are not exceptionally weak, as is the case for high-ionization lines in WLQs. The X-shooter spectra also display relatively strong optical Fe ii emission, Hβ FWHM ≲ 4000 km s−1, and significant C iv blueshifts (≈1000–5500 km s−1) relative to the systemic redshift; two spectra also show elevated UV Fe ii emission, and an outflowing component to their (weak) Mg ii emission lines. These properties suggest that WLQs are exotic versions of “wind-dominated” quasars. Their BELRs either have unusual high-ionization components, or their BELRs are in an atypical photoionization state because of an unusually soft continuum.
Kinetics of Viscosity Decrease by Cellulase Treatment of Bleached Hardwood Kraft-Based Dissolving Pulp

A dissolving pulp of low cellulose viscosity represents a pulp of high quality; hence, it is often necessary to decrease the initial dissolving pulp viscosity. One so-called environmentally friendly approach to further reducing the dissolving pulp viscosity is to treat the dissolving pulp with cellulase enzymes. In this study, the kinetics of the decrease in cellulose viscosity during a cellulase treatment was investigated. The study showed that the kinetics of the cellulose degradation during a cellulase treatment can be divided into at least two phases, where the initial phase is very fast and the final phase is very slow. The kinetic two-phase model for the viscosity degradation that has been developed in this project can be used to predict and control the final pulp viscosity of dissolving pulps.
Brainstorming versus creative design reasoning

In industrial settings, brainstorming is seen as an effective technique for creativity in innovation processes. However, bulk of research on brainstorming is based on an oversimplified view of the creativity process. Participants are seen as idea generators and the process aims at maximizing the quantity of ideas produced, and the evaluation occurs post-process based on some originality and feasibility criteria. Design theories can help enrich this simplistic process model. The present study reports an experimental investigation of creativity process within the context of real-life design ideation task. Results lead to the rejection of the classical 'quantity breeds quality' hypothesis. Rather, we observe that successful groups are the ones who produce a few original propositions that hold great value for users while looking for ways to make those propositions feasible.
A benchmark study of numerical implementations of the sea level equation in GIA modelling

The ocean load in glacial isostatic adjustment (GIA) modelling is represented by the so-called sea level equation (SLE). The SLE describes the mass redistribution of water between ice sheets and oceans on a deforming Earth. Despite various teams independently investigating GIA, there has been no systematic intercomparison among the numerical solvers of the SLE through which the methods may be validated. The goal of this paper is to present a series of synthetic examples designed for testing and comparing the numerical implementations of the SLE in GIA modelling. The 10 numerical codes tested combine various temporal and spatial parametrizations. The time-domain or Laplace-domain discretizations are used to solve the SLE through time, while spherical harmonics, finite differences or finite elements parametrize the GIA-related field variables spatially. The surface ice-water load and solid Earth's topography are represented spatially either on an equiangular grid, a Gauss-Legendre or an equiarea grid with icosahedron-shaped spherical pixels. Comparisons aremade in a series of five benchmark examples with an increasing degree of complexity. Due to the complexity of the SLE, there is no analytical solution to it. The accuracy of the numerical implementations is therefore assessed by the differences of the individual solutions with respect to a reference solution. While the benchmark study does not result in GIA predictions for a realistic loading scenario, we establish a set of agreed-upon results that can be extended in the future by including more complex case studies, such as solutions with realistic loading scenarios, the rotational feedback in the linear-momentum equation, and by considering a 3-D viscosity structure of the Earth's mantle. The test computations performed so far show very good agreement between the individual results and their ability to capture the main features of sea-surface variation and the surface vertical displacement. The differences found can often be attributed to the different approximations inherent in the various algorithms. This shows the accuracy that can be expected from different implementations of the SLE, which helps to assess differences noted in the literature between predictions for realistic loading cases.
An algorithm to compute the Hoffman constant of a system of linear constraints

We propose a combinatorial algorithm to compute the Hoffman constant of a system of linear equations and inequalities. The algorithm is based on a characterization of the Hoffman constant as the largest of a finite canonical collection of easy-to-compute Hoffman constants. Our algorithm and characterization extend to the more general context where some of the constraints are easy to satisfy as in the case of box constraints. We highlight some natural connections between our characterizations of the Hoffman constant and Renegar's distance to ill-posedness for systems of linear constraints.
Temporal recommender systems

This article introduces temporal recommender systems, which are intended for suggesting items in situations where time is an essential factor of the decision-making process. It has been developed on a foundation of empirical research on customer satisfaction and consumption conducted in 12 cafes over a period of 10 days, on a sample consisting of 852 customers, where the time of consumption was recorded. The data was used to create different neural network models for predicting tourist satisfaction and consumption. The results have not only shown variations in customer satisfaction and money spent, in relation to different parameters of consumption, but have also revealed the behavior of different groups of customers in different establishments, competition between different service providers and rivalry between different groups of clients regarding the use of services within the same establishment at the same time. The knowledge thus obtained has been included in a temporal recommender system for visitors of cafes. This system is able to rank and recommend cafes according to predicted customer satisfaction based on their features, cafes' features, particular circumstances, needs, as well as the time of intended consumption. The basic architecture, possible applications, connection with other scientific topics and suggestions for further research on the subject of temporal recommender systems are given. Possible applications of these models will be essential for the application in dynamic mobile recommender systems.
Hermite Forms of Polynomial Matrices

This thesis presents a new algorithm for computing the Hermite form of a polynomial matrix. Given a nonsingular n×n matrix A filled with degree d polynomials with coefficients from a field, the algorithm computes the Hermite form of A using an expected number of (nd) field operations. The algorithm is randomized of the Las Vegas type.