Miracle-dz/UniFAR-FTUs huggingface dataset:
Continuous chain-ladder with paid data

We introduce a continuous-time framework for the prediction of outstanding liabilities, in which chain-ladder development factors arise as a histogram estimator of a cost-weighted hazard function running in reversed development time. We use this formulation to show that under our assumptions on the individual data chain-ladder is consistent. Consistency is understood in the sense that both the number of observed claims grows to infinity and the level of aggregation tends to zero. We propose alternatives to chain-ladder development factors by replacing the histogram estimator with kernel smoothers and by estimating a cost-weighted density instead of a cost-weighted hazard. Finally, we provide a real-data example and a simulation study confirming the strengths of the proposed alternatives.
Nonsmooth backfitting for the excess risk additive regression model with two survival time scales

We consider an extension of Aalen’s additive regression model that allows covariates to have effects that vary on two different time scales. The two time scales considered are equal up to a constant for each individual and vary across individuals, such as follow-up time and age in medical studies or calendar time and age in longitudinal studies. The model was introduced in Scheike (2001), where it was solved using smoothing techniques. We present a new backfitting algorithm for estimating the structured model without having to use smoothing. Estimators of the cumulative regression functions on the two time scales are suggested by solving local estimating equations jointly on the two time scales. We provide large-sample properties and simultaneous confidence bands. The model is applied to data on myocardial infarction, providing a separation of the two effects stemming from time since diagnosis and age.
Modeling of interactions between supernovae ejecta and aspherical circumstellar environments

Context. Massive stars are characterized by a significant loss of mass either via (nearly) spherically symmetric stellar winds or pre-explosion pulses, or by aspherical forms of circumstellar matter (CSM) such as bipolar lobes or outflowing circumstellar equatorial disks. Since a significant fraction of most massive stars end their lives by a core collapse, supernovae (SNe) are always located inside large circumstellar envelopes created by their progenitors. Aims. We study the dynamics and thermal effects of collision between expanding ejecta of SNe and CSM that may be formed during, for example, a sgB[e] star phase, a luminous blue variable phase, around PopIII stars, or by various forms of accretion. Methods. For time-dependent hydrodynamic modeling we used our own grid-based Eulerian multidimensional hydrodynamic code built with a finite volumes method. The code is based on a directionally unsplit Roe’s method that is highly efficient for calculations of shocks and physical flows with large discontinuities. Results. We simulate a SNe explosion as a spherically symmetric blast wave. The initial geometry of the disks corresponds to a density structure of a material that orbits in Keplerian trajectories. We examine the behavior of basic hydrodynamic characteristics, i.e., the density, pressure, velocity of expansion, and temperature structure in the interaction zone under various geometrical configurations and various initial densities of CSM. We calculate the evolution of the SN–CSM system and the rate of aspherical deceleration as well as the degree of anisotropy in density, pressure, and temperature distribution. Conclusions. Our simulations reveal significant asphericity of the expanding envelope above all in the case of dense equatorial disks. Our “low density” model however also shows significant asphericity in the case of the disk mass-loss rate Ṁcsd = 10−6 M⊙ yr−1. The models also show the zones of overdensity in the SN–disk contact region and indicate the development of Kelvin-Helmholtz instabilities within the zones of shear between the disk and the more freely expanding material outside the disk.
SafeAccess: Towards a Dialogue Enabled Access to the Smart Home for the Friends and Families

SafeAccess is an interactive assistive technology solution to enhance the safety and independence of people with disability (i.e., visually impaired and limited mobility). The system output is the classification and identification of a person in front of the door or around the house into groups such as friends/families/caregiver versus intruders/burglars/unknown. This will allow the user to grant/deny remote access to the premises or ability to call emergency services. In this paper, we focus on designing a prototype system and building a robust recognition engine that meets the system criteria and addresses speed, accuracy, deployment and environmental challenges under a wide variety of practical and real-life situations. The premise is assumed to be equipped with cameras placed at strategic locations to capture images and videos. To interact with the system, we implemented a dialog enabled interface to create a personalized profile using face images or video of friend/families/caregiver. To improve the computational efficiency, we apply change detection to filter out frames and use Faster-RCNN to detect the human presence and extract faces using Multitask Cascaded Convolutional Networks (MTCNN). Subsequently, we apply LBP/FaceNet to identify a person and groups by matching extracted faces with the profile. SafeAccess sends identification result to the users with an MMS containing persons name if any match found or as intruder, scene image and a confidence score between 1 to 10. In addition, the daily, weekly and monthly summarized report of the past incident can be queried from the system. Empirical analysis shows a robust performance with an F-score of 0.97 in identifying friends/families/caregiver versus intruders/unknown.
Quantifying and Controlling Prethermal Nonergodicity in Interacting Floquet Matter

The use of periodic driving for synthesizing many-body quantum states depends crucially on the existence of a prethermal regime, which exhibits drive-tunable properties while forestalling the effects of heating. This motivates the search for direct experimental probes of the underlying localized nonergodic nature of the wave function in this metastable regime. We report experiments on a many-body Floquet system consisting of atoms in an optical lattice subjected to ultrastrong sign-changing amplitude modulation. Using a double-quench protocol we measure an inverse participation ratio quantifying the degree of prethermal localization as a function of tunable drive parameters and interactions. We obtain a complete prethermal map of the drive-dependent properties of Floquet matter spanning four square decades of parameter space. Following the full time evolution, we observe sequential formation of two prethermal plateaux, interaction-driven ergodicity, and strongly frequency-dependent dynamics of long-time thermalization. The quantitative characterization of the prethermal Floquet matter realized in these experiments, along with the demonstration of control of its properties by variation of drive parameters and interactions, opens a new frontier for probing far-from-equilibrium quantum statistical mechanics and new possibilities for dynamical quantum engineering.
Impact Strength and Water Uptake Behaviors of Fully Bio-Based PA11-SGW Composites

Composite materials have attracted the attention of some industrial fields due to their lightness and relatively good mechanical properties. One of these properties is impact strength, essential to ensure the processability and application of these materials under impact conditions. In addition, it is known that water absorption has a plasticizing effect in polymers and polymer composites which can change the properties of such materials and limit their use. Moreover, this effect worsens when hydrophilic reinforcement is used. In this work, the impact and water uptake behavior of totally bio-based composites from polyamide 11 (PA11) and lignocellulosic pine fibers mechanically processed as stone groundwood (SGW) were studied. The impact resistance of PA11 and its composites was higher than expected, obtaining better results than those of polyolefin-based materials. The evaluated mechanical properties and the micrographs showed an adequate interface. The water uptake test showed that PA11 and its composites had non-Fickian and Fickian case I behaviours, respectively. It was found that the maximum water absorbance was similar to that of SGW reinforced polypropylene.
Trithiocarbonate-Functionalized PNiPAAm-Based Nanocomposites for Antimicrobial Properties

In this study, four trithiocarbonate-functionalized PNiPAAms with different molecular weights were synthesized and used as a matrix to form composites with silver nanoparticles. Nanocomposites with several polymer-to-silver ratios P:Ag+ were prepared in order to evaluate the influence of silver loading. UV studies showed a thermoresponsive behavior of the nanocomposites with a thermo-reversibility according to cooling-heating cycles. Release kinetics demonstrated that the release of silver ions is mainly influenced by the size of the silver nanoparticles (AgNPs), which themselves depend on the polymer length. Antimicrobial tests against E. coli and S. aureus showed that some of the nanocomposites are antimicrobial and even full killing could be induced.
Polymer-Magnetic Composite Particles of Fe3O4/Poly(o-anisidine) and Their Suspension Characteristics under Applied Magnetic Fields

Fe3O4/poly(o-anisidine) (POA) magnetic composite nanoparticles with their core-shell structure were synthesized by chemical oxidation polymerization technique and adopted as a magneto-responsive magnetorheological (MR) material. The chemical structure and morphology of core-shell nanoparticles were identified by FT-IR, SEM, TEM, and elemental analyzer. Pycnometer and vibrating sample magnetometer showed that the magnetic saturation and density of the Fe3O4/POA particles were reduced by the POA shell coatings. The rheological properties of the MR suspension dispersed in a silicone oil at various magnetic field strengths were investigated using a rotating rheometer under a magnetic field. The resulting MR suspension showed a typical Newtonian fluid behavior in the absence of external stimuli. When an external magnetic field was applied, it formed a strong chain structure, acting like a solid with a yield stress. Further solid-like behaviors were observed from storage shear relaxation and viscoelastic tests. Finally, the Fe3O4/POA nanoparticles showed better dispersion stability than pure Fe3O4 nanoparticles with 50% improvement.
Facile Preparation of Reduction-Responsive Micelles Based on Biodegradable Amphiphilic Polyurethane with Disulfide Bonds in the Backbone

In this paper, we synthesized a biodegradable amphiphilic polymer of polyurethane-polyethylene glycol with disulfide bonds in the main chain (PEG-PU(SS)-PEG). DLS and SEM showed that the polymer could self-assemble into micelles in aqueous solution and could be used to load the hydrophobic anticancer drug DOX. Intriguingly, drug release in vitro indicated that DOX-loaded PEG-PU(SS)-PEG micelles had good stability under the extracellular physiological environment, but the disulfide bonds broke rapidly and DOX was released quickly under the intracellular reducing conditions. CCK-8 assays showed that DOX-loaded PEG-PU(SS)-PEG micelles had a high in vitro antitumor activity in C6 cells, whereas blank PEG-PU(SS)-PEG micelles were nontoxic to C6 cells. It was also found that there was strong and persistent accumulation of DOX-loaded PEG-PU(SS)-PEG as compared with PEG-PU-PEG both by the cell internalization tests and the flow cytometry measurements. Hence, PEG-PU(SS)-PEG micelles will have a potential use for clinical treatment of cancer in the future.
Why Employees Help Teammates When Their Leader Looks Powerful: A Multilevel Investigation

We extend prior research on leader power by examining why and when leader referent and expert powers influence team members’ organizational citizenship behaviors directed at other individuals (OCBI) from the multilevel perspective. We propose that leader referent and expert power perceptions operate at both individual and team levels and lead to OCBI through distinct motivational mechanisms. Drawing upon social identity theory, we suggest that team-level leader referent and expert powers facilitate social identification as salient team features and in turn promote team members’ OCBI through collective team identification. On the other hand, at the individual level, leader referent and expert powers are experienced discretionarily and affect members’ OCBI through dyadic exchange relationships with a leader–member exchange (LMX) based on the reciprocity norm. Furthermore, collective team identification is hypothesized to moderate the relationship between LMX and OCBI. Findings from 465 employees in 80 teams show that team-level leader referent power enhances collective team identification and OCBI beyond expert power but not vice versa. At the individual level, both referent and expert powers have positive indirect impact on OCBI via LMX. The moderating effect of collective team identification is supported in that team members convert high-quality LMX into OCBI only when collective team identification is higher. Theoretical and practical implications of these findings are discussed.
RAFT Polymerization of Tert-Butyldimethylsilyl Methacrylate: Kinetic Study and Determination of Rate Coefficients

Well-defined poly(tert-butyldimethylsilyl methacrylate)s (TBDMSMA) were prepared by the reversible addition-fragmentation chain transfer (RAFT) process using cyanoisopropyl dithiobenzoate (CPDB) as chain-transfer agents (CTA). The experimentally obtained molecular weight distributions are narrow and shift linearly with monomer conversion. Propagation rate coefficients (kp) and termination rate coefficients (kt) for free radical polymerization of TBDMSMA have been determined for a range of temperature between 50 and 80 °C using the pulsed laser polymerization-size-exclusion chromatography (PLP-SEC) method and the kinetic method via steady-state rate measurement, respectively. The CPDB-mediated RAFT polymerization of TBDMSMA has been subjected to a combined experimental and PREDICI modeling study at 70 °C. The rate coefficient for the addition reaction to RAFT agent (kβ1, kβ2) and to polymeric RAFT agent (kβ) is estimated to be approximately 1.8 × 104 L·mol−1·s−1 and for the fragmentation reaction of intermediate RAFT radicals in the pre-equilibrium (k-β1, k-β2) and main equilibrium (k-β) is close to 2.0 × 10−2 s−1. The transfer rate coefficient (ktr) to cyanoisopropyl dithiobenzoate is found to be close to 9.0 × 103 L·mol−1·s−1 and the chain-transfer constant (Ctr) for CPDB-mediated RAFT polymerization of TBDMSMA is about 9.3.
Near-Infrared Light and Solar Light Activated Self-Healing Epoxy Coating having Enhanced Properties Using MXene Flakes as Multifunctional Fillers

Two issues are required to be solved to bring intrinsically self-healing polymer coatings into real applications: remote activation and satisfied practical properties. Here, we used MXene, a newly reported two-dimensional material, to provide an epoxy coating with light-induced self-healing capabilities and we worked to enhance the properties of that coating. The self-healing coatings had a reversible crosslinking network based on the Diels-Alder reaction among maleimide groups from bis(4-maleimidopheny)methane and dangling furan groups in oligomers that were prepared through the condensation polymerization of diglycidylether of bisphenol A and furfurylamine. The results showed that the delaminated MXene flakes were small in size, around 900 nm, and dispersed well in self-healing coatings. The MXene flakes of only 2.80 wt % improved greatly the pencil hardness of the coating hardness from HB to 5H and the polarization resistance from 4.3 to 428.3 MΩ cm−2. The self-healing behavior, however, was retarded by MXene flakes. Leveling agent acted a key part here to facilitate the gap closure driven by reverse plasticity to compensate for the limitation of macromolecular mobility resulting from the MXene flakes. The self-healing of coatings was achieved in 30 s by thermal treatment at 150 °C. The efficient self-healing was also demonstrated based on the recovery of the anti-corrosion capability. MXene flakes also played an evident photothermal role in generating heat via irradiation of near-infrared light at 808 nm and focused sunlight. The healing can be quickly obtained in 10 s under irradiation of near-infrared light at 808 nm having a power density of 6.28 W cm−2 or in 10 min under irradiation of focused sunlight having a power density of 4.0 W cm−2.
A Simple Methodology to Estimate the Diffusion Coefficient in Pervaporation-Based Purification Experiments

A procedure to estimate the diffusion coefficient in solution–diffusion models of hydrophilic membranes used in pervaporation-based purification experiments is presented. The model is based on a series solution of the general permeation problem. It considers a membrane that can be filled with water or with the feed solution before the measurement. Furthermore, the length of the tubing between the permeation cell and the place of cold traps is also addressed. To illustrate the parameter estimation procedure, we have chosen the data for the separation of water and ethanol by chitosan membranes. It is shown that the diffusion coefficient can be estimated effectively from the time course of the transported mass and by the analysis of certain well defined time lags of the permeation curve.
Bleached Kraft Eucalyptus Fibers as Reinforcement of Poly(Lactic Acid) for the Development of High-Performance Biocomposites

Poly(lactic acid) (PLA) is one of the most well-known biopolymers. PLA is bio-based, biocompatible, biodegradable, and easy to produce. This polymer has been used to create natural fiber reinforced composites. However, to produce high-performance and presumably biodegradable composites, the interphase between PLA and natural fibers still requires further study. As such, we aimed to produce PLA-based composites reinforced with a commercial bleached kraft eucalyptus pulp. To become a real alternative, fully biodegradable composites must have similar properties to commercial materials. The results found in this research support the competence of wood fiber reinforced PLA composites to replace other glass fiber reinforced polypropylene composites from a tensile property point of view. Furthermore, the micromechanics analysis showed that obtaining strong interphases between the PLA and the reinforcement is possible without using any coupling agent. This work shows the ability of totally bio-based composites that fulfill the principles of green chemistry to replace composites based on polyolefin and high contents of glass fiber. To the best knowledge of the authors, previous studies obtaining such properties or lower ones involved the use of reagents or the modification of the fiber surfaces.
Human Engineered Cartilage and Decellularized Matrix as an Alternative to Animal Osteoarthritis Model

(1) Objective: to obtain a reproducible, robust, well-defined, and cost-affordable in vitro model of human cartilage degeneration, suitable for drug screening; (2) Methods: we proposed 3D models of engineered cartilage, considering two human chondrocyte sources (articular/nasal) and five culture methods (pellet, alginate beads, silk/alginate microcarriers, and decellularized cartilage). Engineered cartilages were treated with pro-inflammatory cytokine IL-1β to promote cartilage degradation; (3) Results: articular chondrocytes have been rejected since they exhibit low cellular doubling with respect to nasal cells, with longer culture time for cell expansion; furthermore, pellet and alginate bead cultures lead to insufficient cartilage matrix production. Decellularized cartilage resulted as good support for degeneration model, but long culture time and high cell amount are required to obtain the adequate scaffold colonization. Here, we proposed, for the first time, the combined use of decellularized cartilage, as aggrecanase substrate, with pellet, alginate beads, or silk/alginate microcarriers, as polymeric scaffolds for chondrocyte cultures. This approach enables the development of suitable models of cartilaginous pathology. The results obtained after cryopreservation also demonstrated that beads and microcarriers are able to preserve chondrocyte functionality and metabolic activity; (4) Conclusions: alginate and silk/alginate-based scaffolds can be easily produced and cryopreserved to obtain a cost-affordable and ready-to-use polymer-based product for the subsequent screening of anti-inflammatory drugs for cartilage diseases.
Tensile Creep Behavior of Quasi-Unidirectional E-Glass Fabric Reinforced Polypropylene Composite

The present work addressed the creep behavior of quasi-unidirectional E-glass fabric reinforced polypropylene composites under off-axis tensile loading. A series of creep tests were performed on the composite at three different loading stress levels. The creep response of off-axis samples of quasi-unidirectional composites under a constant loading level can be clearly observed. A phenomenological viscoplasticity model was built for describing the creep behavior of the composite. To improve the accuracy of prediction, cyclic loading-unloading tests were adopted to determine the material constants in the model. The predicted results in terms of the strains after a load over a period of time were found to be satisfactory, compared with the experimental results. In addition, same failure mechanism was found in off-axis samples under quasi-static and creep loading cases.
Intra- and Interpolyelectrolyte Complexes of Polyampholytes

At present, a large amount of research from experimental and theoretical points of view has been done on interpolyelectrolyte complexes formed by electrostatic attractive forces and/or interpolymer complexes stabilized by hydrogen bonds. By contrast, relatively less attention has been given to polymer–polymer complex formation with synthetic polyampholytes (PA). In this review the complexation of polyampholytes with polyelectrolytes (PE) is considered from theoretical and application points of view. Formation of intra- and interpolyelectrolyte complexes of random, regular, block, dendritic polyampholytes are outlined. A separate subsection is devoted to amphoteric behavior of interpolyelectrolyte complexes. The realization of the so-called “isoelectric effect” for interpolyelectrolyte complexes of water-soluble polyampholytes, amphoteric hydrogels and cryogels with respect to surfactants, dye molecules, polyelectrolytes and proteins is demonstrated.