cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
A route to room temperature ferromagnetic ultrathin SrRuO$_3$ films
Creators: name: Si, Liang
name: Zhong, Zhicheng
name: Tomczak, Jan M.
name: Held, Karsten
Publisher: name: arXiv
Year: 2015
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Experimental efforts to stabilize ferromagnetism in ultrathin films of transition metal oxides have so far failed, despite expectations based on density functional theory (DFT) and DFT+U. Here, we investigate one of the most promising materials, SrRuO$_3$, and include correlation effects beyond DFT by means of dynamical mean field theory. In agreement with experiment we find an intrinsic thickness limitation for metallic ferromagnetism in SrRuO$_3$ thin films. Indeed, we demonstrate that the realization of ultrathin ferromagnetic films is out of reach of standard thin-film techniques. Proposing charge carrier doping as a new route to manipulate thin films, we predict room temperature ferromagnetism in electron-doped SrRuO$_3$ ultra thin films.
description: 5 pages, 3 figures
Sistemi fortificati piemontesi nel paesaggio costiero urbano di Cagliari: approcci interdisciplinari al progetto di restauro del rudere di Sant’Ignazio
Creators: name: Atzeni, Carlo
name: Fiorino, Donatella Rita
Publisher: name: Restauro Archeologico
Year: 2017

description: This research investigates the effectiveness of Brandi’s ‘uniqueness of method’ principle for the preservation of multi-layered archaeological landscapes, with particular reference to coastal defence systems in urban area. These are strategic places for the defence of historic settlements that are characterized by the persistence of military use from the old age until modern times. The enhancement of these places goes through the integrated knowledge of the artefacts and the deep understanding of mutual contextual relationships at the different scales of analysis - historical, material, architectural, stratigraphic, conservative - in order to generate design projects compatible with the preservation of historical and testimonial values. The paper illustrates the results of integrated scientific investigations and educational programmes conducted on the archaeological defensive area of the Sant’Ignazio fort in Cagliari, built between 1783 and 1798 but never put into service. Reversible and recognizable functional addictions have been designed, interpreting the memory-space-matter triad. These reading deals with Heritage in a contemporary view, according to the idea of continuity in the historical process and confirming the potential of the formal principles of the overlap, integration, support and suspension.
description: Restauro Archeologico, Vol. 25 No. 1 (2017)
Selective distillation phenomenon in two-species Bose-Einstein condensates in open boundary optical lattices
Creators: name: Bai, Xiao-Dong
name: Zhang, Mei
name: Xiong, Jun
name: Yang, Guo-Jian
name: Deng, Fu-Guo
Publisher: name: arXiv
Year: 2015
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We investigate the formation of discrete breathers (DBs) and the dynamics of the mixture of two-species Bose-Einstein condensates (BECs) in open boundary optical lattices using the discrete nonlinear Schrödinger equations. The results show that the coupling of intra- and interspecies interaction can lead to the existence of pure single-species DBs and symbiotic DBs (i.e., two-species DBs). Furthermore, we find that there is a selective distillation phenomenon in the dynamics of the mixture of two-species BECs. One can selectively distil one species from the mixture of two-species BECs and can even control dominant species fraction by adjusting the intra- and interspecies interaction in optical lattices. Our selective distillation mechanism may find potential application in quantum information storage and quantum information processing based on multi-species atoms.
description: 11 pages, 5 figures, one column
Il Follone di Pinerolo (TO), da rinomata manifattura a rudere urbano: prospettive di salvaguardia della memoria
Creators: name: Rudiero, Riccardo
Publisher: name: Restauro Archeologico
Year: 2017

description: The city of Pinerolo was being an important production center thanks to the presence of the Rio Moirano, a flume already documented in the 13th century. Alongside its banks, most of the city's manufactories have been installed, which have been gradually abandoned due to the sector's crisis in the 20th century. Among them, the lace-factory Türk is of particular importance. It settled into the 18th-century Follone, considered among the first modern woolen processing centers. Unfortunate-ly, this building is now in precarious conditions because of the lack of care and protection. Moreover, a part of it has been devastated by a fire and so it is a ruin. Therefore, both materia-lity and memory of this production complex are precarious, due to different conversion hy-potheses which have foreseen the abatement of the building. The article aims to outline the history of this factory-flume system through edited and archi-ved documents, re-examining the instruments used to pursue its protection.
description: Restauro Archeologico, Vol. 25 No. 1 (2017)
Supplementary figures from Hydrodynamics of metachronal paddling: effects of varying Reynolds number and phase lag
Creators: name: Ford, Mitchell P.
name: Lai, Hong Kuan
name: Samaee, Milad
name: Santhanakrishnan, Arvind
Publisher: name: The Royal Society
Year: 2019
Subjects: subject: Biological Engineering
subject: 91504 Fluidisation and Fluid Mechanics
subject: FOS: Other engineering and technologies

description: Negatively buoyant freely swimming crustaceans such as krill must generate downward momentum in order to maintain their position in the water column. These animals use a drag-based propulsion strategy, where pairs of closely spaced swimming limbs are oscillated rhythmically from the tail to head. Each pair is oscillated with a phase delay to the neighbouring pair, resulting in a metachronal wave travelling in the direction of animal motion. It remains unclear how oscillations of limbs in the horizontal plane can generate vertical momentum. Using particle image velocimetry measurements on a robotic model, we observed that metachronal paddling with non-zero phase lag created geometries of adjacent paddles that promote the formation of counter-rotating vortices. The interaction of these vortices resulted in generating large-scale angled downward jets. Increasing phase lag resulted in more vertical orientation of the jet, and phase lags in the range used by Antarctic krill produced the most total momentum. Synchronous paddling produced lower total momentum when compared with metachronal paddling. Lowering Reynolds number by an order of magnitude below the range of adult krill (250–1000) showed diminished downward propagation of the jet and lower vertical momentum. Our findings show that metachronal paddling is capable of producing flows that can generate both lift (vertical) and thrust (horizontal) forces needed for fast forward swimming and hovering.
DIET OF MEGRIM, LEPIDORHOMBUS-WHIFFIAGONIS, IN THE CELTIC-SEA
Creators: name: Dubuit, M. H.
Publisher: name: Station Biologique de Roscoff (SBR)
Year: 1992

description: Megrim is the most abundant flatfish in Celtic Sea and Biscay Bay. Analysis of stomach contents has allowed determination of diet, variations in account size and geographical origin. Fish represents the most important prey in Celtic Sea. All species are swimming fish, Norway pout, blue whiting, horse mackerel. There are no correlation between size of prey and size of predator. Individual consumption has been evaluated 3.14 to 3.33 % of body weight/day.
Supplementary Material from Interactive effects of foundation species on ecosystem functioning and stability in response to disturbance.
Creators: name: Narwani, Anita
name: Reyes, Marta
name: Pereira, Aaron Louis
name: Penson, Hannele
name: Dennis, Stuart R.
name: Derrer, Samuel
name: Spaak, Piet
name: Matthews, Blake
Publisher: name: The Royal Society
Year: 2019
Subjects: subject: Ecology
subject: FOS: Biological sciences

description: Supplementary methods, tables and figures
San Michele Arcangelo a Metelliano, Pieve in val D’Asse: metodologie per il rilevo, la documentazione, la conservazione e la valorizzazione
Creators: name: Pancani, Giovanni
Publisher: name: Restauro Archeologico
Year: 2017

description: The Pieve of San Michele Arcangelo in Metelliano is part of the the territory of Arezzo, in particular is located near Cortona, in the Val d'Esse, at the edge of the Chiana Valley. The eleventh century church, built in a phase immediately preceding to the full maturity of the Romanesque, was rebuilt by the architect Maginardo from Arezzo. The paper considers the problem of the methods and investigation protocols relating to the historical archaeological monuments. For the realization of this study, the work was organized according to the main topics: the survey, its certified reliability, the graphic documentation with the identification of materials and structural problems. For the representation of the drawings, in this first session of studies thematic maps have been created that contain information regarding the identification of materials and the state of degradation; In addition the building's structural survey was made, flanked by evaluation of plastic deformation of the facades.
description: Restauro Archeologico, Vol. 25 No. 1 (2017)
ROLE OF VITAMINS IN BACTERIAL PLANKTON RELATIONSHIPS IN LITTORAL WATERS AND SUPRALITTORAL POOLS .3. RELATIONSHIPS BETWEEN AMOUNT OF VITAMIN-B12 AND POPULATIONS WHICH SYNTHESIZE IT
Creators: name: Martin, J. L. Y.
name: Vacelet, E.
Publisher: name: Station Biologique de Roscoff (SBR)
Year: 1975

Abstract
Angular momentum transport and large eddy simulations in magnetorotational turbulence: the small Pm limit
Creators: name: Meheut, H.
name: Fromang, S.
name: Lesur, G.
name: Joos, M.
name: Longaretti, P. -Y.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Angular momentum transport in accretion discs is often believed to be due to magnetohydrodynamic turbulence mediated by the magnetorotational instability. Despite an abundant literature on the MRI, the parameters governing the saturation amplitude of the turbulence are poorly understood and the existence of an asymptotic behavior in the Ohmic diffusion regime is not clearly established. We investigate the properties of the turbulent state in the small magnetic Prandtl number limit. Since this is extremely computationally expensive, we also study the relevance and range of applicability of the most common subgrid scale models for this problem. Unstratified shearing boxes simulations are performed both in the compressible and incompressible limits, with a resolution up to 800 cells per disc scale height. The latter constitutes the largest resolution ever attained for a simulation of MRI turbulence. In the presence of a mean magnetic field threading the domain, angular momentum transport converges to a finite value in the small Pm limit. When the mean vertical field amplitude is such that β, the ratio between the thermal and magnetic pressure, equals 1000, we find α~0.032 when Pm approaches zero. In the case of a mean toroidal field for which β=100, we find α~0.018 in the same limit. Both implicit LES and Chollet-Lesieur closure model reproduces these results for the α parameter and the power spectra. A reduction in computational cost of a factor at least 16 (and up to 256) is achieved when using such methods. MRI turbulence operates efficiently in the small Pm limit provided there is a mean magnetic field. Implicit LES offers a practical and efficient mean of investigation of this regime but should be used with care, particularly in the case of a vertical field. Chollet-Lesieur closure model is perfectly suited for simulations done with a spectral code.
description: Accepted for publication in A&A
Robust estimation of marginal regression parameters in clustered data
Creators: name: Datta, Somnath
name: Beck, James D
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2014

description: We develop robust methods for analyzing clustered data where estimation of marginal regression parameters is of interest. Inverse cluster size reweighting in the objective function to be minimized is incorporated to handle the issue of informative cluster size. Performance of the resulting estimators is studied by simulation. Large sample inference and variance estimation is carried out. The methodology is illustrated using a periodontal disease dataset.
Approximating the Geisser-Greenhouse sphericity estimator and its applications to diffusion tensor imaging
Creators: name: Zhu, Hongtu
name: Muller, Keith E.
name: Couper, David
name: Clement-Spychala, Meagan E.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2010

description: The diffusion tensor imaging (DTI) protocol characterizes diffusion anisotropy locally in space, thus providing rich detail about white matter tissue structure. Although useful metrics for diffusion tensors have been defined, statistical properties of the measures have been little studied. Assuming homogeneity within a region leads to being able to apply Wishart distribution theory. First, it will be shown that common DTI metrics are simple functions of known test statistics. The average diffusion coefficient (ADC) corresponds to the trace of a Wishart, and is also described as the generalized (multivariate) variance, the average variance of the principal components. Therefore ADC has a known exact distribution (a positively weighted quadratic form in Gaussians) as well as a simple and accurate approximation (Satterthwaite) in terms of a scaled chi square. Of particular interest is that fractional anisotropy (FA) values for given regions of interest are functions of the Geisser-Greenhouse (GG) sphericity estimator. The GG sphericity estimator can be approximated well by a linear transformation of a squared beta random variable. Simulated data demonstrates that the fits work well for simulated diffusion tensors. Applying traditional density estimation techniques for a beta to histograms of FA values from a region allow representing the histogram of hundreds or thousands of values in terms of just two estimates for the beta parameters. Thus using the approximate distribution eliminates the “curse of dimensionality” for FA values. A parallel result holds for ADC.
A NOTE ON DIPLODUS-VULGARIS (GEOFFROY SAINT-HILAIRE), A NEW SPECIES OF FISH IN THE MARINE FAUNA OF THE ROSCOFF AREA
Creators: name: Craignou, Y.
name: Gentil, F.
Publisher: name: Station Biologique de Roscoff (SBR)
Year: 1992

description: A specimen of Diplodus vulgaris is recorded for the first time from Roscoff area.
Additive hazards regression and partial likelihood estimation for ecological monitoring data across space
Creators: name: Zhu, Jun
name: Lin, Feng-Chang
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2012

description: We develop continuous-time models for the analysis of environmental or ecological monitoring data such that subjects are observed at multiple monitoring time points across space. Of particular interest are additive hazards regression models where the baseline hazard function can take on flexible forms. We consider time-varying covariates and take into account spatial dependence via autoregression in space and time. We develop statistical inference for the regression coefficients via partial likelihood. Asymptotic properties, including consistency and asymptotic normality, are established for parameter estimates under suitable regularity conditions. Feasible algorithms utilizing existing statistical software packages are developed for computation. We also consider a simpler additive hazards model with homogeneous baseline hazard and develop hypothesis testing for homogeneity. A simulation study demonstrates that the statistical inference using partial likelihood has sound finite-sample properties and offers a viable alternative to maximum likelihood estimation. For illustration, we analyze data from an ecological study that monitors bark beetle colonization of red pines in a plantation of Wisconsin.
A note on the relationships between multiple imputation, maximum likelihood and fully Bayesian methods for missing responses in linear regression models
Creators: name: Chen, Qingxia
name: Ibrahim, Joseph G.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2013

description: Multiple Imputation, Maximum Likelihood and Fully Bayesian methods are the three most commonly used model-based approaches in missing data problems. Although it is easy to show that when the responses are missing at random (MAR), the complete case analysis is unbiased and efficient, the aforementioned methods are still commonly used in practice for this setting. To examine the performance of and relationships between these three methods in this setting, we derive and investigate small sample and asymptotic expressions of the estimates and standard errors, and fully examine how these estimates are related for the three approaches in the linear regression model when the responses are MAR. We show that when the responses are MAR in the linear model, the estimates of the regression coefficients using these three methods are asymptotically equivalent to the complete case estimates under general conditions. One simulation and a real data set from a liver cancer clinical trial are given to compare the properties of these methods when the responses are MAR.
Aspects of epizoobiontic mollusc assemblages on Pinna shells. II. Does the Mediterranean P. nobilis represent an isle of biodiversity?
Creators: name: COSENTINO, Andrea
name: GIACOBBE, Salvatore
Publisher: name: Station Biologique de Roscoff (SBR)
Year: 2008

description: Epizoic molluscs on 49 specimens of the soft-bottom megabenthic bivalve Pinna nobilis Linné, 1758 sampled
 in the Straits of Messina (Central Mediterranean), were investigated. Univariate indices of biodiversity, based on richness,
 abundance/evenness and taxonomic relatedness were calculated on mollusc taxocommunity in accordance with bathymetry
 and shell size of the P. nobilis. Furthermore, a multivariate composition of the characterizing epizoic taxa, and the
 corresponding functional role were investigated; the contribution of basibionts in increasing mollusc diversity on a small
 scale (soft bottom habitat/biotope), as well as a large scale (regional biogeography) was also tested. Epizoic mollusc
 assemblage replicates some major characteristics of hard bottom assemblages which are tied to ephemeral photophilous
 algae, but also displays some peculiar typological and taxonomic characteristics, probably related to the selective effect of
 the living substratum. Gastropod to bivalve ratio ranges from 4.0 to 5.6:1 in number of species, and from 5.6 to 12.6:1 in
 abundance, in accordance to shell size. Bittium reticulatum (Da Costa, 1778), Rissoella inflata Locard, 1892 and Gibbula
 turbinoides (Deshayes, 1835) are the prevalent species, but percentage similarity analysis and non-parametric correlation
 emphasize at least two multispecies subsets, which contribute to typologically and functionally characterize the mollusc
 taxocommunity. The recurrent occurrence of cladistically and functionally related microgastropods may suggest a possible
 specific redundancy or, alternatively, a functional complementarity depending on the ephemeral macrophytal epigrowth.
 The peculiar mollusc fauna associated with P. nobilis makes this bivalve a meaningful biodiversity reservoir both on the
 small and large spatial scale. Estimations of local density of Pinna populations, joined with species accumulation curves of
 associated taxa, allows the assessment of minimal patch of bottom surfaces which may sustain a rich network o
The quenched critical point for self-avoiding walk on random conductors
Creators: name: Chino, Yuki
name: Sakai, Akira
Publisher: name: arXiv
Year: 2015
Subjects: subject: Probability (math.PR)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 82B26, 82D30

description: Following similar analysis to that in Lacoin (PTRF 159, 777-808, 2014), we can show that the quenched critical point for self-avoiding walk on random conductors on the d-dimensional integer lattice is almost surely a constant, which does not depend on the location of the reference point. We provide its upper and lower bounds that are valid for all dimensions.
description: 14 pages
Bayesian case-deletion model complexity and information criterion
Creators: name: Ibrahim, Joseph G.
name: Chen, Qingxia
name: Zhu, Hongtu
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2014

description: We establish a connection between Bayesian case influence measures for assessing the influence of individual observations and Bayesian predictive methods for evaluating the predictive performance of a model and comparing different models fitted to the same dataset. Based on such a connection, we formally propose a new set of Bayesian case-deletion model complexity (BCMC) measures for quantifying the effective number of parameters in a given statistical model. Its properties in linear models are explored. Adding some functions of BCMC to a conditional deviance function leads to a Bayesian case-deletion information criterion (BCIC) for comparing models. We systematically investigate some properties of BCIC and its connection with other information criteria, such as the Deviance Information Criterion (DIC). We illustrate the proposed methodology on linear mixed models with simulations and a real data example.
Rare variant testing across methods and thresholds using the multi-kernel sequence kernel association test (MK-SKAT)
Creators: name: Wu, Michael C.
name: Shen, Judong
name: Li, Yun
name: Urrutia, Eugene
name: Lee, Seunggeun
name: Zhao, Ni
name: Maity, Arnab
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2015

description: Analysis of rare genetic variants has focused on region-based analysis wherein a subset of the variants within a genomic region is tested for association with a complex trait. Two important practical challenges have emerged. First, it is difficult to choose which test to use. Second, it is unclear which group of variants within a region should be tested. Both depend on the unknown true state of nature. Therefore, we develop the Multi-Kernel SKAT (MK-SKAT) which tests across a range of rare variant tests and groupings. Specifically, we demonstrate that several popular rare variant tests are special cases of the sequence kernel association test which compares pair-wise similarity in trait value to similarity in the rare variant genotypes between subjects as measured through a kernel function. Choosing a particular test is equivalent to choosing a kernel. Similarly, choosing which group of variants to test also reduces to choosing a kernel. Thus, MK-SKAT uses perturbation to test across a range of kernels. Simulations and real data analyses show that our framework controls type I error while maintaining high power across settings: MK-SKAT loses power when compared to the kernel for a particular scenario but has much greater power than poor choices.
Avoiding bias in mixed model inference for fixed effects
Creators: name: Edwards, Lloyd J.
name: Gurka, Matthew J.
name: Muller, Keith E.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2011

description: Analysis of a large longitudinal study of children motivated our work. The results illustrate how accurate inference for fixed effects in a general linear mixed model depends on the covariance model selected for the data. Simulation studies have revealed biased inference for the fixed effects with an underspecified covariance structure, at least in small samples. One underspecification common for longitudinal data assumes a simple random intercept and conditional independence of the within-subject errors (i.e., compound symmetry). We prove that the underspecification creates bias in both small and large samples, indicating that recruiting more participants will not alleviate inflation of the Type I error rate associated with fixed effect inference. Enumerations and simulations help quantify the bias and evaluate strategies for avoiding it. When practical, backwards selection of the covariance model, starting with an unstructured pattern, provides the best protection. Tutorial papers can guide the reader in minimizing the chances of falling into the often spurious software trap of nonconvergence. In some cases, the logic of the study design and the scientific context may support a structured pattern, such as an autoregressive structure. The sandwich estimator provides a valid alternative in sufficiently large samples. Authors reporting mixed-model analyses should note possible biases in fixed effects inference because of the following: (i) the covariance model selection process; (ii) the specific covariance model chosen; or (iii) the test approximation.
Archeologia ferroviaria: la stazione di Fermo e le opere d’arte della Ferrovia Adriatico Appennino.
Creators: name: Saracco, Mauro
name: Petetta, Leonardo
name: Cecchi, Chiara
Publisher: name: Restauro Archeologico
Year: 2017

description: The italian railway network has several disused lines and many of them cross high-quality landscapes. The artifacts, built to realize these infrastructural networks, remain in rural and mountain areas as 'archaeological ruins' of larger and extensive works. The conservation and enhancement of these 'ruins', allows not to miss an important historical and material evidences, of social and economic development of many Italian regions. In this perspective has been addressed the study of the Railway Adriatico-Amandola, in the Marche region, and the ex-railway station of Fermo, defining a possible pilot project able to recover the historical memory of the places through a compatible reuse and a new relationship with the city and the territory.
description: Restauro Archeologico, Vol. 25 No. 1 (2017)
Supplementary Material from Interactive effects of foundation species on ecosystem functioning and stability in response to disturbance
Creators: name: Narwani, Anita
name: Reyes, Marta
name: Pereira, Aaron Louis
name: Penson, Hannele
name: Dennis, Stuart R.
name: Derrer, Samuel
name: Spaak, Piet
name: Matthews, Blake
Publisher: name: The Royal Society
Year: 2019
Subjects: subject: Ecology
subject: FOS: Biological sciences

description: Supplementary methods, tables and figures
Maximum likelihood estimation in generalized linear models with multiple covariates subject to detection limits
Creators: name: Ibrahim, Joseph G.
name: Chu, Haitao
name: May, Ryan C.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2011

description: The analysis of data subject to detection limits is becoming increasingly necessary in many environmental and laboratory studies. Covariates subject to detection limits are often left censored because of a measurement device having a minimal lower limit of detection. In this paper, we propose a Monte Carlo version of the expectation–maximization algorithm to handle large number of covariates subject to detection limits in generalized linear models. We model the covariate distribution via a sequence of one-dimensional conditional distributions, and sample the covariate values using an adaptive rejection metropolis algorithm. Parameter estimation is obtained by maximization via the Monte Carlo M-step. This procedure is applied to a real dataset from the National Health and Nutrition Examination Survey, in which values of urinary heavy metals are subject to a limit of detection. Through simulation studies, we show that the proposed approach can lead to a significant reduction in variance for parameter estimates in these models, improving the power of such studies.
NOTE ON THE IDENTIFICATION OF ENSIS-DIRECTUS (CONRAD, 1843)
Creators: name: Luczak, C.
name: Dewarumez, J. M.
Publisher: name: Station Biologique de Roscoff (SBR)
Year: 1992

description: Ensis directus occured for first time in high number in the French part of the North Sea in spring 1991. Identification of specimens smaller than 15 mm is difficult because of easy confusion with Ensis arcuatus. For longer animals, a length/height ratio of 6:1 is a reliable criterion of identification for Ensis directus after the three other constants and reliable characters described by de Boer (1984).
title: Badania modelowe generatorów udarów testowych do badań niskonapięciowych ograniczników przepięć
Creators: name: Drużyński, Łukasz
name: Janiszewski, Jerzy
Publisher: name: Publishing House of Poznan University of Technology
Year: 2021

description: Poznan University of Technology Academic Journals. Electrical Engineering, 106, 85-97
Exponential Decay of Correlations for Finite Horizon Sinai Billiard Flows
Creators: name: Baladi, Viviane
name: Demers, Mark
name: Liverani, Carlangelo
Publisher: name: arXiv
Year: 2015
Subjects: subject: Dynamical Systems (math.DS)
subject: Mathematical Physics (math-ph)
subject: Spectral Theory (math.SP)
subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 37D50 (Primary), 37C30, 37D20, 37E35, 46E35, 47B38 (Secondary)

description: We prove exponential decay of correlations for the billiard flow associated with a two-dimensional finite horizon Lorentz Gas (i.e., the Sinai billiard flow with finite horizon). Along the way, we describe the spectrum of the generator of the corresponding semi-group L_t of transfer operators, i.e., the resonances of the Sinai billiard flow, on a suitable Banach space of anisotropic distributions. (Revised after referees' comments.)
description: v2: Revised version after referees' comments. (The homogeneity layers do not appear anymore in the def. of the norm.) The text published in Invent. Math. is v2, but has more pages (due to smaller margins in v2). v3: Contains an additional 2-page note correcting flaws found by M. Jezequel (L 3.2) and D. Thomine (L 4.6 and L 7.5)
A simulation study of finite-sample properties of marginal structural Cox proportional hazards models
Creators: name: Westreich, Daniel
name: Schisterman, Enrique F.
name: Platt, Robert W.
name: Cole, Stephen R.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2012

description: Motivated by a previously published study of HIV treatment, we simulated data subject to time-varying confounding affected by prior treatment to examine some finite-sample properties of marginal structural Cox proportional hazards models. We compared (a) unadjusted, (b) regression-adjusted, (c) unstabilized and (d) stabilized marginal structural (inverse probability-of-treatment [IPT] weighted) model estimators of effect in terms of bias, standard error, root mean squared error (MSE) and 95% confidence limit coverage over a range of research scenarios, including relatively small sample sizes and ten study assessments. In the base-case scenario resembling the motivating example, where the true hazard ratio was 0.5, both IPT-weighted analyses were unbiased while crude and adjusted analyses showed substantial bias towards and across the null. Stabilized IPT-weighted analyses remained unbiased across a range of scenarios, including relatively small sample size; however, the standard error was generally smaller in crude and adjusted models. In many cases, unstabilized weighted analysis showed a substantial increase in standard error compared to other approaches. Root MSE was smallest in the IPT-weighted analyses for the base-case scenario. In situations where time-varying confounding affected by prior treatment was absent, IPT-weighted analyses were less precise and therefore had greater root MSE compared with adjusted analyses. The 95% confidence limit coverage was close to nominal for all stabilized IPT-weighted but poor in crude, adjusted, and unstabilized IPT-weighted analysis. Under realistic scenarios, marginal structural Cox proportional hazards models performed according to expectations based on large-sample theory and provided accurate estimates of the hazard ratio.
Game Design and Analysis for Price based Demand Response: An Aggregate Game Approach
Creators: name: Ye, Maojiao
name: Hu, Guoqiang
Publisher: name: arXiv
Year: 2015
Subjects: subject: General Economics (econ.GN)
subject: Systems and Control (eess.SY)
subject: Optimization and Control (math.OC)
subject: FOS: Economics and business
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Mathematics

description: In this paper, an aggregate game approach is proposed for the modeling and analysis of energy consumption control in smart grid. Since the electricity user's cost function depends on the aggregate load, which is unknown to the end users, an aggregate load estimator is employed to estimate it. Based on the communication among the users about their estimations on the aggregate load, Nash equilibrium seeking strategies are proposed for the electricity users. By using singular perturbation analysis and Lyapunov stability analysis, a local convergence result to the Nash equilibrium is presented for the energy consumption game that may have multiple Nash equilibria. For the energy consumption game with a unique Nash equilibrium, it is shown that the players' strategies converge to the Nash equilibrium non-locally. More specially, if the unique Nash equilibrium is an inner Nash equilibrium, then the convergence rate can be quantified. Energy consumption game with stubborn players is also investigated. Convergence to the best response strategies for the rational players is ensured. Numerical examples are provided to verify the effectiveness of the proposed methods.
Comparing competing risk outcomes within principal strata, with application to studies of mother-to-child transmission of HIV
Creators: name: Hudgens, Michael G.
name: Long, Dustin M.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2012

description: In randomized trials to prevent breast milk transmission of human immunodeficiency virus (HIV) from mother to infant, investigators are often interested in assessing the effect of a treatment or intervention on the cumulative risk of HIV infection by time (age) t in infants who are alive and uninfected at a certain time point τ0 < t. Such comparisons are challenging for two reasons. First, infants are typically randomized at birth (time 0 < τ0) such that comparisons between trial arms among the subset of infants alive and uninfected at τ0 are subject to selection bias. Second, in most mother-to-child transmission (MTCT) trials competing risks are often present, such as death or cessation of breastfeeding prior to HIV infection. In this paper we present methods for assessing the causal effect of a treatment on competing risk outcomes within principal strata. In MTCT trials, the causal effect of interest is that of treatment on the risk of HIV infection by time t > τ0 within the principal stratum of infants who would be alive and uninfected by τ0 regardless of randomization assignment. Large sample non-parametric bounds and a semi-parametric sensitivity analysis model are developed for drawing inference about this causal effect. A simulation study is presented demonstrating that the proposed methods perform well in finite samples. The proposed methods are applied to a large, recent MTCT trial.
The role of quantum non-Gaussian distance in entropic uncertainty relation
Creators: name: Son, Wonmin
Publisher: name: arXiv
Year: 2015
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Gaussian distribution of a quantum state with continuous spectrum is known to maximize the Shannon entropy at a fixed variance. Applying it to a pair of canonically conjugate quantum observables $\hat x$ and $\hat p$, quantum entropic uncertainty relation can take a suggestive form, where the standard deviations $σ_x$ and $σ_p$ are featured explicitly. From the construction, it follows in a transparent manner that: (i) the entropic uncertainty relation implies the Kennard-Robertson uncertainty relation in a modifed form, $σ_xσ_p\geq\hbar e^{\cal N}/2$; (ii) the additional factor ${\cal N}$ quantifies the quantum non-Gaussianity of the probability distributions of two observables; (iii) the lower bound of the entropic uncertainty relation for non-gaussian continuous variable (CV) mixed state becomes stronger with purity. Optimality of specific non-gaussian CV states to the refined uncertainty relation has been investigated and the existance of new class of CV quantum state is identified.
description: 7 figures
New species of the genus Diarthrodes Thomson, 1882 (Copepoda: Harpacticoida: Thalestridae) from Vietnam and North-western Mexico
Creators: name: GÓMEZ, Samuel
name: CHERTOPRUD, Elena S.
name: MORALES-SERNA, Francisco Neptalí
Publisher: name: Station Biologique de Roscoff (SBR)
Year: 2008

description: Some specimens of the family Thalestridae (Copepoda: Harpacticoida) were gathered from sediment samples
 taken in the framework of two short term studies about the effects of organic enrichment on the diversity of benthic
 copepods from two brackish coastal systems in central (Ensenada del Pabellón lagoon) and southern (Urías system) Sinaloa
 during the early 1990's and during 2005. Also some specimens of the same family were found in sediment samples taken
 in year 2004 during a study about the distribution and biogeography of harpacticoid copepods from Southern Vietnam. The
 specimens collected turned out to belong to five new species of Diarthrodes: D. imitator sp. nov., D. tripartitus sp. nov.,
 D. hexasetosus sp. nov., D. nhatrangensis sp. nov. and D. savinkinii sp. nov. Seven species groups (I (1-2-2), II (1-2-3), III
 (2-1-3), IV (3-1-3), V (2-2-3), VI (3-2-2), VII (3-2-3)) are herein defined based on the number of segments of the exopod
 of the antenna, and on the number of segments of the exopod and endopod of the first swimming leg. Another new species
 attributed to group I (1-2-2), Diarthrodes apostolovii sp. nov., is created based on previous illustrations of D. assimilis from
 the Black Sea.
Supplementary information from Earlier colony arrival but no trend in hatching timing in two congeneric seabirds (Uria spp.) across the North Atlantic.
Creators: name: Merkel, Benjamin
name: Descamps, Sébastien
name: Yoccoz, Nigel G.
name: Jóhannis Danielsen
name: Daunt, Francis
name: Erikstad, Kjell E.
name: Ezhov, Aleksey V.
name: Grémillet, David
name: Gavrilo, Maria
name: Svein-Håkon Lorentsen
name: Reiertsen, Tone K.
name: Steen, Harald
name: Systad, Geir H.
name: Þórarinsson, Þorkell Lindberg
name: Wanless, Sarah
name: Strøm, Hallvard
Publisher: name: The Royal Society
Year: 2019
Subjects: subject: Ecology
subject: FOS: Biological sciences
subject: 60801 Animal Behaviour

description: A global analysis recently showed that seabird breeding phenology (as the timing of egg-laying and hatching) does not, on average, respond to temperature changes or advance with time (Keogan et al. 2018 Nat. Clim. Change 8, 313–318). This group, the most threatened of all birds, is therefore prone to spatio-temporal mismatches with their food resources. Yet, other aspects of the breeding phenology may also have a marked influence on breeding success, such as the arrival date of adults at the breeding site following winter migration. Here, we used a large tracking dataset of two congeneric seabirds breeding in 14 colonies across 18° latitudes, to show that arrival date at the colony was highly variable between colonies and species (ranging 80 days) and advanced 1.4 days/year while timing of egg-laying remained unchanged, resulting in an increasing pre-laying duration between 2009 and 2018. Thus, we demonstrate that potentially not all components of seabird breeding phenology are insensitive to changing environmental conditions.
Meta-analysis methods and models with applications in evaluation of cholesterol-lowering drugs
Creators: name: Lin, Jianxin
name: Shah, Arvind K.
name: Chen, Ming-Hui
name: Yao, Hui
name: Ibrahim, Joseph G.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2012

description: In this paper, we propose a class of multivariate random effects models allowing for the inclusion of study-level covariates to carry out meta-analyses. As existing algorithms for computing maximum likelihood estimates often converge poorly or may not converge at all when the random effects are multi-dimensional, we develop an efficient expectation–maximization algorithm for fitting multi-dimensional random effects regression models. In addition, we also develop a new methodology for carrying out variable selection with study-level covariates. We examine the performance of the proposed methodology via a simulation study. We apply the proposed methodology to analyze metadata from 26 studies involving statins as a monotherapy and in combination with ezetimibe. In particular, we compare the low-density lipoprotein cholesterol-lowering efficacy of monotherapy and combination therapy on two patient populations (naïve and non-naïve patients to statin monotherapy at baseline), controlling for aggregate covariates. The proposed methodology is quite general and can be applied in any meta-analysis setting for a wide range of scientific applications and therefore offers new analytic methods of clinical importance.
Two-stage designs for Phase 2 dose-finding trials
Creators: name: Ivanova, Anastasia
name: Tymofyeyev, Yevgen
name: Xiao, Changfu
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2012

description: We propose a Bayesian adaptive two-stage design for the efficient estimation of the maximum dose or the minimum effective dose in a dose-finding trial. The new design allocates subjects in stage two according to the posterior distribution of the target dose location. Simulations show that the proposed two-stage design is superior to equal allocation and to a two-stage strategy where only one dose is left in the second stage.
Use of alternative time scales in Cox proportional hazard models: implications for time-varying environmental exposures
Creators: name: Shih, Regina A.
name: Anderson, Garnet L.
name: Whitsel, Eric A.
name: Griffin, Beth Ann
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2012

description: Issues surrounding choice of time scales in Cox proportional hazard regression models have received limited attention in the literature. Although the choice between time on study and ‘attained’ age time scales has been examined, the calendar time scale may be of interest when modeling health effects of environmental exposures with noteworthy secular trends such as ambient particulate matter air pollution in large epidemiological cohort studies. The authors use simulation studies to examine performance (bias, mean squared error, coverage probabilities, and power) of models using all three time scales when the primary exposure of interest depends on calendar time. Results show that performance of models fit to the calendar time scale varies inversely with the strength of the linear association between the time-varying primary exposure and calendar time. Although models fit to attained age and time on study that do not adjust for calendar time were relatively robust, the authors conclude that care should be exercised when using time scales that are highly correlated with exposures of interest.
A Bayesian approach to strengthen inference for case-control studies with multiple error-prone exposure assessments
Creators: name: Chu, Haitao
name: Zhang, Jing
name: Cole, Stephen R.
name: Richardson, David B.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2013

description: In case-control studies, exposure assessments are almost always error-prone. In the absence of a gold standard, two or more assessment approaches are often used to classify people with respect to exposure. Each imperfect assessment tool may lead to misclassification of exposure assignment; the exposure misclassification may be differential with respect to case status or not; and, the errors in exposure classification under the different approaches may be independent (conditional upon the true exposure status) or not. Although methods have been proposed to study diagnostic accuracy in the absence of a gold standard, these methods are infrequently used in case-control studies to correct exposure misclassification that is simultaneously differential and dependent. In this paper, we proposed a Bayesian method to estimate the measurement-error corrected exposure-disease association, accounting for both differential and dependent misclassification. The performance of the proposed method is investigated using simulations, which show that the proposed approach works well, as well as an application to a case-control study assessing the association between asbestos exposure and mesothelioma.
Plasma motions and non-thermal line broadening in flaring twisted coronal loops
Creators: name: Gordovskyy, Mykola
name: Kontar, Eduard
name: Browning, Philippa
Publisher: name: arXiv
Year: 2015
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Observation of coronal EUV spectral lines sensitive to different temperatures offers an opportunity to evaluate the thermal structure and flows in flaring atmospheres. This can be used to estimate the partitioning between the thermal and kinetic energies. Our aim is to model large-scale (50-10000km) velocity distributions in order to interpret non-thermal broadening of different spectral EUV lines. The developed models allow us to understand the origin of the observed spectral line shifts and broadening, and link these features to particular physical effects in flaring atmospheres. We use ideal MHD to derive twisted magnetic fluxtube configurations in a stratified atmosphere. The evolution of these fluxtubes is followed using resistive MHD, with anomalous resistivity depending on the local density and temperature. The model also takes into account the thermal conduction and radiative losses. The model allows us to evaluate average velocities and velocity dispersions, which would be interpreted as `non-thermal' velocities in observations, at different temperatures for different parts of the models. Our models show qualitative and quantitative agreement with observations. The line-of-sight (LOS) velocity dispersions demonstrate substantial correlation with the temperature, increasing from about 20-30 km/s around 1 MK to about 200-400 km/s near 10-20 MK. The average LOS velocities also correlate with velocity dispersions, although they demonstrate a very strong scattering, compared to observations. We also note that near foot-points the velocity dispersions across the magnetic field are systematically lower than those along the field. We conclude, that the correlation between the flow velocities, velocity dispersions and temperatures are likely to indicate that the same heating mechanism is responsible for heating the plasma, its turbulisation and expansion/evaporation.
description: Accepted to Astronomy & Astrophysics