Miracle-dz/UniFAR-FTUs huggingface dataset:
The Gravity Model for International Trade: Specification and Estimation Issues

Abstract The Poisson gravity model along with pseudo maximum likelihood (ML) methods has become a popular way to model international trade flows. This approach has several econometric advantages that we outline in the paper. We argue that estimating the parameters by ML would only be justified statistically if the trade flows were independent. Such an assumption, however, is generally not valid, and a failure to account for spatial dependence may lead to biased parameter estimates and misleading inferences. To overcome this estimation problem we suggest eigenvector spatial filtering variants of the Poisson gravity model (without and with zero-inflation) along with pseudo ML estimation.
Topological Properties of Wireless Sensor Networks Under the Q-Composite Key Predistribution Scheme With Unreliable Links (CMU-CyLab-14-002)

The seminal q-composite key predistribution scheme [3] (IEEE S&P 2003) is used prevalently for secure communications in large-scale wireless sensor networks (WSNs). Yagan [12] (IEEE IT 2012) and we [15] (IEEE ISIT 2013) explore topological properties of WSNs employing the q-composite scheme in the case of q = 1 with unreliable communication links modeled as independent on/off channels. However, it is challenging to derive results for general q under such on/off channel model. In this paper, we resolve such challenge and investigate topological properties related to node degree in WSNs operating under the q-composite scheme and the on/off channel model. Our results apply to general q, yet there has not been any work in the literature reporting the corresponding results even for q = 1, which are stronger than those about node degree in [12], [15]. Specifically, we show that the number of nodes with an arbitrary degree asymptotically converges to a Poisson distribution, present the asymptotic probability distribution for the minimum node degree of the network, and establish the asymptotically exact probability for the property that the minimum node degree is at least an arbitrary value. Numerical experiments confirm the validity our analytical findings.
Spatial fluctuations of spin and orbital nature in the two-orbital Hubbard model

We investigate the quasiparticle dynamics in the two-orbital Hubbard model on the square lattice at quarter filling by means of the cellular dynamical mean-field theory. We show that the Fermi-liquid state is stabilized up to the large Hubbard interactions in the symmetric case without Hund's coupling, and find the heavy quasiparticles around the metal-insulator boundary. It is elucidated that Hund's coupling enhances the antiferro-orbital correlations, which give rise to the pseudogap behavior in the single-particle excitations. We also find the nonmonotonic temperature dependence in the quasiparticle dynamics for intermediate strength of Hund's coupling, and clarify that it is caused by the competition between the Fermi-liquid formation and the antiferro-orbital fluctuations.
Radio Emission of the Solar Polar Regions at Millimeter Wavelengths

Regions of enhanced radio brightness in the polar areas of the Sun were detected in 1974 at the Crimean Astrophysical Observatory of the Academy of Sciences of the U.S.S.R. The effective temperatures of these regions exceeded that of the undisturbed Sun by 1500 K and 2200 K at 8.2 and 13.5 mm wavelengths respectively. Radio brightness distributions of the Sun obtained with the 22-m radio telescope, at 8.2 and 13.5 mm with angular resolutions of l! 6 and 2155 respectively are shown in Figure 1. Regions of enhanced radio brightness near the North Pole of the Sun are seen, beside the typical s-sources at middle and low latitudes.
Shape sensitive geometric complexity

The traditional algorithm analysis for geometric problems has focused on worst-case asymptotic complexity. Such analyses have often concluded that certain simple algorithms are worthless because they have poor worst-case performance. However, empirical experience shows that these algorithms tend to perform very well in practice. How does one explain this disparity? This dissertation uses shape sensitive analysis to explores this phenomenon by investigating two problems: the use of bounding boxes in collision detection, and the complexity of geometric permutations in visibility computation. Bounding boxes are used widely in computer graphics as simple approximations of complex objects. Because of their simpler shape, computing with boxes is almost always easier and faster than with the original objects. Experience has shown that the use of bounding boxes greatly improves the performance of geometric algorithms in collision detection, rendering and modeling. However, the goal of proving that bounding boxes maintain high performance in the worst case has remained elusive. In fact, traditional analysis of algorithms has concluded that in the worst-case bounding boxes add nothing but overhead. We will show how to reconcile this discrepancy using shape-sensitive analysis. Our proof shows that the performance of bounding boxes depends on two natural shape parameters of objects, and the observed efficiency of boxes can be attributed to the fact that objects in practice tend to have small values of these parameters. The second part of this thesis focuses on the complexity of geometric permutations. Geometric permutations are a natural analog of the more familiar numerical permutation. Given a set of disjoint convex bodies in some fixed d-dimensional space, a geometric permutation is the order in which these objects can be intersected by a line. We will be interested in the “combinatorics” of such permutations—namely, given n objects in d-space, how many combinatorially distinct geometric permutations are possible. Our breakthrough result is that a set of n unit balls in Rd admits at most a constant number of geometric permutations. The constant bound significantly improves upon the Θ(n d−1) bound for the balls of arbitrary radii. Intrigued by this large gap between the two bounds, we then study how the number of geometric permutations varies as a function of shape, size, and spacing of objects.
Spatial Contact Models for Ecological and Epidemic Spread

A wide variety of phenomena of geographical spread can be described in terms of a mechanism of "growth" (e.g, birth, infection) and a "contact distribution" which describes how the locations of the individual(s) involved in a migratory move, or infection at a distance, are spatially related. I shall survey work on such models, beginning with an examination of the relations between stochastic and deterministic models; it emerges that both linear and nonlinear deterministic models have close connections with the less interesting "linear" (exponential growth) stochastic models. More realistic models must be nonlinear as well as stochastic; some results are now available for such models. As in the linear case, these deal mainly with asymptotic behaviour. Simulations reveal that nonlinear stochastic processes have a richer spectrum of non-asymptotic behaviour than linear models, though in some circumstances the simpler models may provide an adequate approximation. Thus theoretical study of the short-term behaviour of such processes may be difficult, but should prove rewarding. The other main outstanding problems are those of inference for such models, especially the estimation of contact distributions.
Parity violation in the nucleon-nucleon interaction

A short review is presented of experiments designed to detect parity nonconservation (PNC) in the interaction between nucleons. A recent measurement of PNC in proton-proton scattering is described, and some of the methods which were developed to reduce systematic errors to less than or equal to 2 x 10/sup -8/ are discussed. The results of this experiment and of other measurements on PNC are compared to theoretical predictions.
Extreme Ultraviolet Explorer Investigation of Three Short-Period Binary Stars

Extreme Ultraviolet Explorer spectroscopic observations (SW, MW, and LW bands, covering 80–160, 170–350, and 300–450 Å with resolutions 0.5, 1, and 2 Å, respectively) and photometric observations (Deep Sky Survey [DSS], broadband 70–140 Å) have been obtained for two contact binaries, 44i Boo B and VW Cep, and one close but detached binary, ER Vul. All three systems have orbital periods shorter than 1 day and thus are expected to show "saturated" levels of chromospheric, transition region, and lower corona emissions. Only moderate flaring activity was seen in the DSS light curves of all three stars. The phased DSS light curve of 44i Boo B shows one minimum at the eclipse of the hotter, smaller component, while the phased light curve of ER Vul has a slightly higher level at the first maximum, following the deeper eclipse. An unsuccessful attempt has been made to determine the temperature dependence of the differential emission measure (DEM) of the coronal plasma for 44i Boo B on the basis of iron ion emission lines. It utilized the singular value decomposition formalism developed by Schmitt et al. to handle the inverse problem of the spectrum-to-DEM mapping. Implementation of this formalism suffered from the low number of available spectral features and possibly also inconsistencies in the line strengths, which become amplified in the mathematical inversion process. However, experiments with the direct reconstruction of the spectra, which were generated with the DEM functions available from the literature, favor the distribution of Dupree et al. in preference to the two-temperature model of McGale et al. A comparison of the relative line fluxes fline/fbol for selected strongest chromospheric, transition region, and low-corona emission lines in 44i Boo B, VW Cep, ER Vul, and the single, rapidly rotating star AB Dor shows that the currently available data are consistent with the period-independent ("saturated") levels of activity for features forming at log T ≤ 5 in all four stars, while features formed at log T ≃ 6.8–7.1 are definitely the weakest in AB Dor.
Ensembles profinis simpliciaux et interpr'etation g'eom'etrique du foncteur T

Pour chaque nombre premier p, on munit la categorie des ensembles profinis simpliciaux d'une structure de categorie de modeles fermee dans laquelle les equivalences faibles sont les applications induisant un isomorphisme en cohomologie modulo p continue. En utilisant la construction du p-complete de Bousfield-Kan d'un espace, on obtient tout d'abord une version rigide de la p-completion profinie de Artin-Mazur et Sullivan et l'on en deduit une interpretation geometrique concrete du foncteur T introduit par J. Lannes (qui generalise celle de Dror-Smith).
Polynomials whose coefficients are k-Fibonacci numbers

Let {an}n≥0 denote the linear recursive sequence of order k (k ≥ 2) defined by the initial values a0 = a1 = · · · = ak−2 = 0 and ak−1 = 1 and the recursion an = an−1 + an−2 + · · · + an−k if n ≥ k. The an are often called k-Fibonacci numbers and reduce to the usual Fibonacci numbers when k = 2. Let Pn,k(x) = ak−1x n + akx n−1 + · · · + an+k−2x + an+k−1, which we will refer to as a k-Fibonacci coefficient polynomial. In this paper, we show for all k that the polynomial Pn,k(x) has no real zeros if n is even and exactly one real zero if n is odd. This generalizes the known result for the k = 2 and k = 3 cases corresponding to Fibonacci and Tribonacci coefficient polynomials, respectively. It also improves upon a previous upper bound of approximately k for the number of real zeros of Pn,k(x). Finally, we show for all k that the sequence of real zeros of the polynomials Pn,k(x) when n is odd converges to the opposite of the positive zero of the characteristic polynomial associated with the sequence an. This generalizes a previous result for the case k = 2.
Variational based analysis and modelling using B-splines

The use of energy methods and variational principles is widespread in many fields of engineering of which structural mechanics and curve and surface design are two prominent examples. In principle many different types of function can be used as possible trial solutions to a given variational problem but where piecewise polynomial behaviour and user controlled cross segment continuity is either required or desirable, B-splines serve as a natural choice. Although there are many examples of the use of B-splines in such situations there is no common thread running through existing formulations that generalises from the one dimensional case through to two and three dimensions. We develop a unified approach to the representation of the minimisation equations for Bspline based functionals in tensor product form and apply these results to solving specific problems in geometric smoothing and finite element analysis using the Rayleigh-Ritz method. We focus on the development of algorithms for the exact computation of the minimisation matrices generated by finding stationary values of functionals involving integrals of squares and products of derivatives, and then use these to seek new variational based solutions to problems in the above fields. By using tensor notation we are able to generalise the methods and the algorithms from curves through to surfaces and volumes. The algorithms developed can be applied to other fields where a variational form of the problem exists and where such tensor product B-spline functions can be specified as potential solutions.
On the Ergodic Theorem for Positive Linear Operators.

Let X denote a space with points χ and let there be given a σ-additive and σ-finite measure defined on all sets belonging to a given σ-field of subsets of X. All integrals //? / = / (#)» x $ ̂ are formed with this measure. If no domain of Integration is indicated ff is extended through all of X. Denote by L = D-(X) the linear space of all functions f(x) integrable in X and consider a mapping T = Tf of L int o L which is linear and positive, / ^ 0 (in X) -* Tf ^ 0 (in X ) . A previous paper) of the author dealt with those positive linear operators from L to L which conserve the integral, fTf = ff. They are closely connected with Markoff processes in X, and positivity and conservation of the integral arise simply from the requirement that a probability distribution in Xgoes over again into such a distribution. The author tried unsuccessfully to prove that the quotients (ra = l, 2, . . .)
Re/Presentation of Asian Americans in 50 States’ K–12 U.S. History Standards

Abstract This study is a content analysis of K–12 U.S. history curriculum standards from 50 states regarding curricular re/presentation of Asian Americans. The guiding research questions are as follows: (1) What is the frequency of Asian American content covered in K–12 U.S. history standards from 50 states? (2) How do the standards depict Asian Americans in U.S. history? I analyzed U.S. history curriculum standards from all states using AsianCrit as a theoretical lens. The findings reveal that except for Japanese incarceration and anti-Asian immigration laws, Asian Americans are largely invisible in the state standards and, when included, they are primarily depicted as victims of nativist racism with a lack of civic agency as well as new immigrants with little contribution to nation-building. Being the first work to uncover curricular messages about Asian Americans across 50 states’ standards, this study presents a necessary empirical basis for disrupting curriculum violence.
Exploring parents’ perceptions of preschoolers’ risky outdoor play using a socio-ecological lens

ABSTRACT Outdoor play with its risks is necessary for optimal child development. Increasing attention is being paid to factors influencing children's opportunities for risky outdoor play, with parent/guardian (hereafter parent) perceptions being an important, under-researched topic. This research explored parents’ perceptions of preschoolers’ risky outdoor play. Interviews were held with 19 parents of preschoolers in Nova Scotia, Canada. Bronfenbrenner's ecological model was used to consider levels of influence related to parents’ perceptions of risky outdoor play. A qualitative descriptive approach identified key themes from interviews. Microsystem-level factors influencing parents’ perceptions included children's age, size, ability to self-assess, and comfort with risk. Mesosystem-level factors were children's companions and supervision during play. Exosystem-level factors included neighborhood location, perceived safety, and house type. Macrosystem and chronosystem-level factors included how parents’ perceptions of weather and season affected children's play, and the influences of higher societal expectations of injury avoidance on children's play over time. Findings can be used to inform strategies to promote children's quality outdoor play through understanding the factors influencing parents’ perceptions of preschoolers’ risky outdoor play.
A construct modelling approach to characterize chemistry students’ understanding of the nature of light

ABSTRACT Across science disciplines, light is a common tool for measuring, characterizing, and catalysing molecules and molecular processes. Despite the ubiquity of light-based tools, little research has been done to investigate how students understand light and light–matter interactions (LMI). This topic is typically first introduced in first-year undergraduate chemistry courses where students initially encounter the quantum nature of light and matter. How students make sense of this content and transition from classical concepts to quantum concepts is relatively unknown. To gain further insight on how students develop quantum-level conceptions about light, we use a construct modelling approach. This approach is best suited to capture progressions in student understanding. In this study, we begin to model students’ understanding of LMI by first developing a model for the nature of light. Two sets of qualitative interviews were conducted about the particulate nature of light and the wave nature of light. Analysis of interviews resulted in four construct maps, which can provide information to instructors and researchers about the variation in student understanding of the nature of light. Findings from this study have implications for how quantum chemistry is introduced at the postsecondary level.
Interfacial thermal conductance between gold and SiO2: A molecular dynamics study

ABSTRACT Silica coating on a gold nanoparticle can improve its thermal application in cancer thermotherapy. In this paper, the interfacial thermal conductance between gold and silica is calculated utilizing classical non-equilibrium molecular dynamics. It is revealed that the results of molecular dynamics are different from what has been predicted by the conventional diffuse mismatch model. Furthermore, the interfacial thermal conductance between amorphous SiO2 and gold is approximately twice that of crystalline silica, which is explained by calculating the vibrational density of state mismatches. The interfacial thermal conductance variations in terms of van der Waals interaction strength between gold and silica are also investigated. It is revealed that the conductance increases by about 30% by increasing the simulation temperature from 300 to 700 K. The results of this paper can be useful in nanofluid systems, in addition to the application of silica-coated gold nanoparticles in cancer thermal therapy.
PLK4 drives centriole amplification and apical surface area expansion in multiciliated cells

Multiciliated cells (MCCs) are terminally differentiated epithelia that assemble multiple motile cilia used to promote fluid flow. To template these cilia, MCCs dramatically expand their centriole content during a process known as centriole amplification. In cycling cells, the master regulator of centriole assembly Polo-like kinase 4 (PLK4) is essential for centriole duplication; however recent work has questioned the role of PLK4 in centriole assembly in MCCs. To address this discrepancy, we created genetically engineered mouse models and demonstrated that both PLK4 protein and kinase activity are critical for centriole amplification in MCCs. Tracheal epithelial cells that fail centriole amplification accumulate large assemblies of centriole proteins and do not undergo apical surface area expansion. These results show that the initial stages of centriole assembly are conserved between cycling cells and MCCs and suggest that centriole amplification and surface area expansion are coordinated events.
Copy number flexibility facilitates heteroresistance to increasing antibiotic pressure and threatens the beta-lactam pipeline

It is unclear how bacteria rapidly adapt to resist novel drugs upon their introduction. Heteroresistance (HR) is a form of antibiotic resistance where a phenotypically unstable minority resistant subpopulation co-exists with a susceptible population. We observed HR to cefiderocol, a novel beta-lactam developed to resist beta-lactamases including extended-spectrum-beta-lactamases (ESBLs), among clinical isolates collected before its use. The resistant subpopulation in Enterobacter was a continuum; increasing gene copy number of an otherwise ineffective ESBL mediated increased resistance in decreasing numbers of cells. The factors that control the magnitude of amplification are unclear. We observed that ESBL activity controlled the level of amplification, thus increased copy number can compensate for poor enzymatic activity. A Klebsiella isolate from a clinical treatment failure also demonstrated amplification, highlighting the relevance of this phenomenon. These data provide insights into factors controlling dynamics of HR and how bacteria use phenotypic resistance to flexibly confront new antibiotic threats.
Linear Operators And Linear Systems

The theory of linear operators has had an important influence on the development of mathematical systems theory. On the other hand, mathematical systems theory serves as a direct source of motivation and new techniques for the theory of linear operators and its applications. The subseries "Linear Operators and Linear Systems¿ (LOLS) is dedicated to these connections between the theory of linear operators and the mathematical theory of linear systems. LOLS will continue in the tradition of the series Operator Theory: Advances and Applications and maintain the high quality of the volumes. Books published in LOLS will be either monographs or consist of essays presenting the state of the art and new results. The volumes will be addressed to a wide range of mathematicians from beginners to experts in these fields.
PARAMED: Stata module to perform causal mediation analysis using parametric regression models

paramed performs causal mediation analysis using parametric regression models. Two models are estimated: a model for the mediator conditional on treatment (exposure) and covariates (if specified), and a model for the outcome conditional on treatment (exposure), the mediator and covariates (if specified). It extends statistical mediation analysis (widely known as Baron and Kenny procedure) to allow for the presence of treatment (exposure)-mediator interactions in the outcome regression model using counterfactual definitions of direct and indirect effects. paramed allows continuous, binary or count outcomes, and continuous or binary mediators, and requires the user to specify an appropriate form for the regression models. paramed provides estimates of the controlled direct effect, the natural direct effect, the natural indirect effect and the total effect with standard errors and confidence intervals derived using the delta method by default, with a bootstrap option also available.