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The timing and spectral properties of the 2022 outburst of SGR J1935+2154 observed with NICER
No full textThe magnetar SGR J1935+2154 entered a new active episode on 2022 October 10, with X-ray bursts and enhanced persistent emission. At the tail of a high burst rate interval, lasting several hours, radio bursts were detected, revealing the connection between the X-ray activities and radio emissions. We analyzed observations of SGR J1935+2154 for nearly 3 months, using data from the Neutron Star Interior Composition Explorer. We report the timing and spectral results following the onset of this outburst. In general, the X-ray flux of the persistent emission decays exponentially. While a flare is evident on the light curve, a fast radio burst (FRB) was detected immediately following the peak of this flare. We found a phase jump in the pulse profile, with a deviation of a 0.16 ± 0.03 phase, which is related to the glitch. The spectra are well fit with the combination of a blackbody and a power-law (PL) model. The decay of the outburst is dominated by the drop in the nonthermal component, which also leads to an increase in thermal proportion. The photon index of the PL is inversely correlated with both the unabsorbed flux and the burst rate. We find that unlike the large variety of the persistent emission around FRB 221014, the X-ray properties are very stable when FRBs 221021 and 221201 happened. These results manifest the connection between the glitch, phase jump, X-ray burst, and radio burst, crucial for studying the mutation in twisted magnetic fields and constraining the trigger mechanism of radio bursts
A comparative fractographic analysis for the effect of polymeric nanofiber reinforcements on the tensile behavior of multi-layered epoxy nanocomposites
No full textThis study presents a comparative investigation into the effects of four different nanofibers—PA66, PStX, PAN, and PVB—on the mechanical performance and failure mechanisms of epoxy adhesive films. These nanofiber-reinforced adhesive layers were manufactured via a dry-reinforcement resin film infusion method and tested under uniaxial tensile loading. Mechanical results showed that PA66 and PStX nanofibers improved tensile strength by up to 25%, primarily by mitigating crack initiation at free edges and promoting effective fiber–matrix bonding. In contrast, PAN nanofibers induced micro-cracks at the fiber–resin interface, amplifying crack coalescence and reducing strength by 25%. PVB nanofibers, which lost their fibrous morphology due to a relatively low glass transition temperature, formed a separate polymeric phase with a negligible reinforcement effect. Detailed fractographic analyses identified key features—ratchet marks, ridges, interlayer failures, and river lines—that elucidate how nanofiber type, compatibility with the epoxy matrix, and cure conditions dictate the final failure modes. A “top-down” approach to fractography revealed that manufacturing-induced free-edge cracks and nanofiber-based interactions converge to influence the ultimate tensile performance of these adhesive films. Finally, a fishbone diagram synthesizes the findings, offering a practical reference for the effects of fiber selection, processing parameters, and testing protocols in developing high-performance, nanofiber-reinforced epoxy adhesive films. Highlights: Tensile failure mechanisms for novel laminated nanofiber/epoxy nanocomposites. Effect of nanofiber base polymer choice on mechanical response of epoxy adhesive films. Multi-scaled perspective for efficient fractographic analysis. A top to bottom approach on failure analysis of nanocomposites
Emotions and the status quo: the anti-incumbency bias in political prediction markets
No full textEmotions are often associated with politics, with new research confirming this connection. There is a link between negative emotions and political actions that oppose an incumbent candidate or party. We examine whether this “anti-incumbency” bias extends to political prediction markets, where such emotions can conflict with economic rationality. We analyze unique data from Media Predict, a commercial prediction market. Before a trade is executed, participants are asked to write a justification for their actions. Using text analysis, we measure the emotional sentiment of the justifications of traders buying contracts predicting a change in the incumbent candidate or party. Consistent with anti-incumbency bias, the justifications of buyers of a challenger contract had significantly more negative emotional sentiment scores. We document this finding in prediction markets associated with the 2012 US Presidential Election and the 2015 UK General Election. We conclude that, despite incentives to the contrary, traders’ actions in political stock markets are associated with strong emotions tied to incumbency status
On Cohen-Macaulay non-prime collections of cells
No full textIn this paper we investigate Cohen-Macaulayness, Gorensteinness and the Hilbert-Poincaré series for some classes of non-prime collections of cells. In particular, we show that all closed path polyominoes are Cohen-Macaulay and we characterize those that are Gorenstein
Comparative study of pectin and kappa-carrageenan-based films loaded with boswellic acid and acetyl-11-keto-beta-boswellic acid for active packaging
No full textActive packaging is crucial for extending shelf life, maintaining food quality, and reducing reliance on synthetic preservatives by preventing spoilage, oxidation, and microbial contamination. In this study, boswellic acid (BA) and acetyl-11-keto-beta-boswellic acid (AKBA) were isolated from the oleo-gum resin of Boswellia sacra and incorporated into the pectin and kappa-carrageenan-based films for active packaging. The fabricated films were analyzed to examine the effect of these active compounds on the mechanical, optical, barrier, chemical, structural, hydrophobic, and antioxidant properties. The incorporation of AKBA and BA into the films resulted in a decrease in transparency and tensile strength; however, the elongation at break did not show any significant variations. The film samples exhibited improved antioxidant properties as confirmed by DPPH and ABTS free radical scavenging activities. The ΔE value represented the overall color difference in AKBA- and BA-loaded films as compared with the blank film sample. The FTIR spectrum of AKBA- and BA-loaded films exhibited shifts and intensity changes, suggesting the intermolecular interaction within the film matrix. Moreover, the water contact angle measurements revealed that the films containing AKBA showed a noticeable increase in contact angles, reflecting an enhancement in hydrophobicity. The current study offers a valuable approach for developing active packaging films with potential applications in food packaging
Decoding digital engagement: a comparative analysis of English and Turkish brand post popularity dynamics on platform X
No full textPurpose: This research aims to understand the dynamics that drive consumer engagement of multinational brands' social media posts on platform X, formerly known as Twitter. Taking the emotional tone of posts into account, the effect of vivid, interactive, informative, entertaining and practical features of posts on consumer interactions are evaluated across English- and Turkish-speaking markets. Methodology: Inspired by the conceptual framework proposed in previous literature, features were extracted computationally using natural language processing from platform X posts of 33 Fortune 500 brands from various industries from June 2016 to June 2021. Following evaluation of regression models on alternative distributions of the dependent variable, which is total number of likes, shares and comments, random subspace regression using bootstrap resampling was applied to calculate an importance score and evaluate the effect of features. Findings: Consumers in English- and Turkish-speaking markets perceive and engage with content differently. While informative and entertaining posts resonate more with English speakers, emotions play a broader role for Turkish speakers. English-speaking audience prefers happy and vivid daytime messages with questions, while Turkish-speaking audience is drawn to angry messages, lean toward nighttime posts. Originality: This research is a pioneer to evaluate the factors that influence brands' platform X post engagements across markets of different cultural orientation. Beyond assessing the distinctions in brand post elements, the role of emotional content in brand messages were also analyzed across English- and Turkish-speaking markets
Regret in global equity markets
No full textThis paper investigates the relation between investment regret and the cross-section of equity returns in an international context. We measure the level of regret from investing in a stock as the negative of the difference between the stock's return and the maximum return that could have been achieved by a stock either in the same industry or with a similar market capitalization or book-to-market ratio. We find that the positive relation between regret and future equity returns is stronger for equal-weighted portfolios suggesting that it is more acute for small stocks. Moreover, the regret effect is stronger in emerging markets compared to developed markets. Furthermore, size-based regret is more pronounced compared to industry- or value-based regret. The regret effect is more prevalent in countries characterized by short-term orientation, capital controls and higher limits-to-arbitrage
The effect of spacer layer thickness on the exchange bias between NiFe and polycrystalline IrMn: experiment and micromagnetic simulations
No full textBy inserting a non-magnetic Cu layer between permalloy (NiFe) and polycrystalline iridium manganese (IrMn) thin films with (111) and a mixture of (002) textures, the dependence of exchange bias, coercive field and magnetic reversal mechanism on the spacer layer thickness has been investigated both experimentally and by micromagnetic simulation technique in the temperature range of 10-300 K. Magnetic force microscopy measurements display a surface magnetic domain structure with random orientations in (002) texture regions and uniform orientations in (111) textured regions consistent with the polycrystalline structure of IrMn. Magnetization measurements reveal that the exchange bias, coercive fields, switching field values exhibit an exponential decline with increasing thickness of the Cu spacer layer. Suggesting that the observed decrease is solely attributable to the weakening of the interaction between Py and IrMn rather than any proximity effects due to the presence of a Cu spacer. Additionally, the magnetic coupling strength between Py and IrMn along the Cu spacer layer is temperature dependent such that at 100 K the exchange bias exhibits long-range characteristics, while above this temperature it displays short-range characteristics. The decay of exchange bias with increasing the spacer layer thickness was modelled to determine the temperature dependence of the characteristic decay length. Finally, detailed micromagnetic simulations were able to reproduce the low temperature experimental hysteresis curves in agreement with phenomenological models using coherent rotation of magnetization
Lab-scale manufacturing of thermoplastic matrix-continuous carbon fiber filaments for additive manufacturing: melt impregnation, properties of the filaments and its printed composites
No full textAdditive manufacturing encounters significant barriers to its broader application in large-scale production. This research seeks to mitigate critical limitations, including a trade-off between impregnation speed and quality in filament preparation and inconsistent fiber distribution in continuous carbon filaments (CCFs), mainly attributed to the rounding process of unidirectional tapes and insufficient interlayer adhesion. A novel lab-scale impregnation line was engineered to address these challenges, facilitating the production of CCFs using three distinct types of carbon fiber in conjunction with recycled glycol-modified poly(ethylene terephthalate) (rPETG) resin. This new lab-scale process produces uniform fiber distribution within PETG matrix and prevents S-shaped distortions typically observed in conventionally rounded tapes. The type of carbon fiber sizing influences the impregnation process and tensile strength of the CCFs. Specifically, CCFs with flexible sizing demonstrated a 15% reduction in tensile strength due to fuzz formation during impregnation. These CCFs were subsequently employed in 3D printing applications, with the fabricated composite components subjected to interlaminar shear strength (ILSS) testing. The study concludes that recycled PETG is a viable additive manufacturing material when combined with appropriately sized carbon fibers. Additionally, it highlights the advantages of omitting the rounding stage, which enhances the quality of CCF and optimizes production efficiency. Highlights: A lab-scale direct melt impregnation system was designed in this study. The impact of different sizing types on carbon fibers was investigated. 3D-printed continuous fiber filaments were prepared. New lab-scale process produces uniform fiber distribution within PETG matrix. S-shaped distortions observed in conventionally rounded tapes were prevented
A highly selective electrochemical sensor by using bimetallic metal organic framework for the detection of 3-Monochloropropane-1,2-diol esters (3-MCPDEs)
No full text3-Monochloropropane-1,2-diol esters (3-MCPDEs) are hazardous contaminants in heat-processed foods, raising serious food safety concerns. In this study, a high-performance Fe-Mn-MOF/NIF sensor was developed via a simple hydrothermal method for rapid and precise 3-MCPDEs detection. Structural and morphological analyses confirmed the sensor stability, with FTIR revealing strong interactions between (-CH) and (O-H) stretching vibrations, while XRD indicated slight crystal distortion upon detection. FESEM and TEM confirmed minimal aggregation, ensuring homogeneous iron (Fe) and manganese (Mn) distribution. The sensor exhibited a large surface area, significantly enhancing its detection capability. Using square wave voltammetry (SWV) method, it achieved a broad linear range (0.05–255 µM), low detection limit (0.002 µM), and exceptional sensitivity (43.71 µA µM−1 cm−2). Comparative analysis with GC-MS demonstrated comparable accuracy, while real-sample testing in soy sauce confirmed high recovery rates. Unlike conventional methods, this sensor enables cost-effective, rapid, and on-site detection, offering a transformative approach for food safety monitoring. With its superior performance, the Fe-Mn-MOF/NIF sensor presents a breakthrough in electrochemical detection, paving the way for enhanced food quality control and public health protection