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Brown dwarf number density in the JWST COSMOS-Web field
No full textBrown dwarfs are failed stars with very low mass (13 to 75 Jupiter mass), and an effective temperature lower than 2500 K. Their mass range is between Jupiter and red dwarfs. Thus, they play a key role in understanding the gap in the mass function between stars and planets. However, due to their faint nature, previous searches are inevitably limited to the solar neighbourhood (20 pc). To improve our knowledge of the low mass part of the initial stellar mass function and the star formation history of the MilkyWay, it is crucial to find more distant brown dwarfs. Using JamesWebb Space Telescope (JWST) COSMOS-Web data, this study seeks to enhance our comprehension of the physical characteristics of brown dwarfs situated at a distance of kpc scale. The exceptional sensitivity of the JWST enables the detection of brown dwarfs that are up to 100 times more distant than those discovered in the earlier all-sky infrared surveys. The large area coverage of the JWST COSMOS-Web survey allows us to find more distant brown dwarfs than earlier JWST studies with smaller area coverages. To capture prominent water absorption features around 2.7 μm, we apply two colour criteria, F115W - F277W + 1 0.9. We then select point sources by CLASS_STAR, FLUX_RADIUS, and SPREAD_MODEL criteria. Faint sources are visually checked to exclude possibly extended sources. We conduct SED fitting and MCMC simulations to determine their physical properties and associated uncertainties. Our search reveals 25 T-dwarf candidates and 2 Y-dwarf candidates, more than any previous JWST brown dwarf searches. They are located from 0.3 kpc to 4 kpc away from the Earth. The spatial number density of 900-1050 K dwarf is (2.0 ± 0.9) × 10-6 pc-3, 1050-1200 K dwarf is (1.2 ± 0.7) × 10-6 pc-3, and 1200-1350 K dwarf is (4.4 ± 1.3) × 10-6 pc-3. The cumulative number count of our brown dwarf candidates is consistent with the prediction from a standard double exponential model. Three of our brown dwarf candidates were detected by HST, with transverse velocities 12 ± 5 km s-1, 12 ± 4 km s-1, and 17 ± 6 km s-1. Along with earlier studies, the JWST has opened a new window of brown dwarf research in the MilkyWay thick disk and halo
Wearable armband with a floating mobile exploratory electrode at fingertip for on-demand touch-and-measure multilead electrocardiography
No full textSpurred by the global pandemic, research in health monitoring has pivoted towards the development of smart garments, enabling long-Term tracking of individuals' cardiovascular health by continuously monitoring the electrocardiogram (ECG) and detecting any abnormality in the signal morphology. Many types of dry electrodes have been proposed as alternatives to gold standard Ag/AgCl wet electrodes, and they have been integrated into clothes capable of acquiring only a limited number of the different ECG traces. This limitation severely diminishes the diagnostic utility of the collected ECG data and obstructs the garment's potential for clinical-level evaluation. Here, we demonstrate a special ECG upper armband with a glove component which houses graphene-Textile electrodes, where a fully mobile, exploring electrode located at the index finger enables the user to strategically position the electrode on-demand to desired body areas and measure the different ECG traces that are bipolar limb and unipolar chest leads. Based on measurements with and without employing the well-known Wilson Central Terminal (WCT) arrangement, the correlation ratio of unipolar ECG chest leads acquired with the graphene textile-based armband and Ag/AgCl electrodes both in WCT-less configuration reach up to %99.65; and up to %99.54 when Ag/AgCl electrodes are utilized with WCT while the graphene-based armband in WCT-less configuration. To the authors' best knowledge, this study reports the first multilead on-demand touch-And-measure ECG recording from a fully wearable textile garment. Moreover, owing to the human-centered armband design, we achieved a more than three-fold reduction in electrode count from 10 in clinical ECG practice down to 3
From cafés to clinics: consumer attitudes toward human-like and machine-like service robot failures
No full textThis study examines consumer evaluations of robotic service failures caused by human interference by integrating service context, robot appearance, and individual anthropomorphism tendencies into a unified model. Two between-subjects experiments were conducted. In Study 1 (N = 402), participants interacted with a healthcare or food-service bot that failed due to verbal interference. Healthcare service failure elicited significantly more negative attitudes and lower failure tolerance than food service failure, and failure tolerance fully mediated the relationship between context and attitudes. In Study 2 (N = 213), we employed a 2 × 2 design (healthcare vs. food services × human-like vs. machine-like robot) and measured perceived deservingness and trait anthropomorphism. Human-like robots were judged most harshly when failing in healthcare (vs. food) services, whereas machine-like robots received similar evaluations across contexts. Perceived deservingness of the robot mediated this interaction. Moreover, the moderated-mediation effect occurred only among individuals with low to medium anthropomorphism tendencies. By positioning failure tolerance and deservingness judgments as core mechanisms in human–robot interaction, our findings advance theoretical understanding of moral attributions in service failure. Practically, they highlight the importance of matching robot anthropomorphic cues to service criticality: less human-like designs in high-stakes environments, while more human-like appearances may be appropriate in lower-stakes settings
Analysis of direct and indirect relations among sustainable development goals and transportation targets
No full textThe United Nations' 2030 Agenda for Sustainable Development emphasizes the integration of 17 Sustainable Development Goals (SDGs), with transportation playing a pivotal role in achieving many of them. Transportation systems not only influence economic development and environmental sustainability but are also critical in improving road safety (SDG 3.6), developing resilient infrastructure (SDG 9.1), and ensuring inclusive urban mobility (SDG 11.2). This study employs fuzzy cognitive mapping and scenario analysis to investigate the intricate relationships among selected SDGs (SDG 2, 3, 7, and 14) and transportation-related targets. It reveals direct and indirect interactions between SDGs and transportation indicators, proposing a roadmap for policy interventions that capitalize on synergies and mitigate trade-offs. This work contributes to transport policy discourse by highlighting how transportation functions as both a catalyst and outcome of sustainable development
Brain functional connectivity during first- and third-person visual imagery
No full textThe ability to adopt different perspectives, or vantage points, is fundamental to human cognition, affecting reasoning, memory, and imagery. While the first-person perspective allows individuals to experience a scene through their own eyes, the third-person perspective involves an external viewpoint, which is thought to demand greater cognitive effort and different neural processing. Despite the frequent use of perspective switching across various contexts, including modern media and in therapeutic settings, the neural mechanisms differentiating these two perspectives in visual imagery remain largely underexplored. In an exploratory fMRI study, we compared both activation and task-based functional connectivity underlying first-person and third-person perspective taking in the same 26 participants performing two spatial egocentric imagery tasks, namely imaginary tennis and house navigation. No significant differences in activation emerged between the first-person and third-person conditions. The network-based statistics analysis revealed a small subnetwork of the early visual and posterior temporal areas that manifested stronger functional connectivity during the first-person perspective, suggesting a closer sensory recruitment loop, or, in different terms, a loop between long-term memory and the “visual buffer” circuits. The absence of a strong neural distinction between the first-person and third-person perspectives suggests that third-person imagery may not fully decenter individuals from the scene, as is often assumed
Lithium-induced defect centers in nanorod-shaped zinc oxide for supercapacitor applications
No full textLithium (Li) doped ZnO nanorods were synthesized in this work using the hydrothermal method by varying the Li ions concentration. The synthesized material was used as an electrode material for supercapacitor application, and the effect of the Li ions on the electrochemical properties was reported. The Li-doped ZnO nanorods were characterized using X-ray diffraction, electron microscopy, and Raman spectroscopy to obtain information on the structural and morphological environment. Electron paramagnetic resonance, Raman, and photoluminescence spectroscopy gave information on the defect environment of the materials, which plays a vital role in this work as a change in the defect structure directly influences the electrochemical properties. Finally, the electrochemical performance of the electrode materials was tested by assembling all-in-one supercapacitor devices using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic cycling with potential limitations as testing techniques. The result obtained showed extremely positive trends for this type of electrode material. The maximum specific capacitance was achieved for the 0.5% Li-doped ZnO, which showed a value of 700 F/g at 1 mV/s with an impressive energy density of 56 Wh/kg and excellent cyclic stability
MOOCs and economic disadvantage: a path analysis of 3.5 million MITx learners
No full textMassive Online Open Courses (MOOCs) are offered by universities and companies to provide quality education to anyone, anyplace and at any time. The impact of economic disadvantage on these courses has not been fully explored despite several studies. This study aimed to investigate the impact of country’s income level on the success of 3,523,692 learners from 204 countries enrolled in 174 MITx MOOCs. The countries were classified as low- and lower-middle-income (L&LM) or high- and upper-middle-income (H&UM). A structural equation modelling with multigroup analysis conducted. The findings revealed that learners in the L&LM group performed better academically. Completion rates were 66% for L&LM and 25% for H&UM, and certification rates were 95% for L&LM and 99% for H&UM. This shows that L&LM learners may be more motivated because they believe MOOCs might help their careers. These results are essential for creating MOOCs that fit diverse learner demographics
A typology of competitive strategies for social enterprises
No full textThis article tackles the limited theorising on social enterprises’ (SEs) decisions on the product or service mix, quality, pricing, and the targeted beneficiaries by proposing a typology of competitive strategies for them. The paper empirically observes how SEs react to the challenges faced by the marketisation of their fields. The context of this study is the supplementary education of the disabled in Turkey, a field where increased state coverage led to the entrance of many profit-focussed counterparts. Based on a Grounded Theory methodology and a longitudinal dataset including ten cases, the study developed a unique typology comprising three competitive strategies, i.e., innovator, enforcer, and includer. The findings illustrate various strategic responses to heightened competition from incumbent SEs. However, deviation of these strategic responses from the typology appeared to be detrimental in the long-term. By shedding light on the intricacies of the hybrid nature of SEs and considering changes in their competitive environment over time, this study concludes with a summary of contributions to theory, practice, and policy
Mitigating the impact of late internationalization of emerging market SMEs: a dynamic capability perspective
No full textIn this study, we investigate the impact of internationalization timing on the export performance of small and medium-sized enterprises (SMEs) in emerging markets. Our theoretical foci are the learning advantage of newness theory and the dynamic capability perspective to focus on how late internationalization can adversely affect export performance. Our findings suggest that the dynamic capabilities and industry experience of the SME Manager can mitigate these adverse effects. The time since initial international entry and an informal approach during export commencement exacerbate them. This conclusion is based on examining a substantial dataset, encompassing 8,278 SMEs from 84 emerging economies, collected over 14 years (2006–2020). This study uncovers novel insights into the intricate dynamics of SME internationalization and its influence on export performance.
Small and medium-sized (SME) businesses from emerging markets are rapidly expanding into international markets. This shift is making SMEs reconsider their traditional ideas about business. Traditionally, SMEs commence selling their products abroad later in their life cycle. However, a trend has recently occurred where many SMEs are internationalizing earlier. However, we have yet to learn why this is happening and whether it helps or harms the businesses. Our study looks into this topic by examining the impacts of SMEs from emerging markets who go international early. We collected data from over 8,000 such businesses across 84 emerging markets between 2006 and 2020. We focused on how the managers' experience and ability to adapt quickly to new circumstances affected the businesses' success in selling their products abroad. We found that businesses that went international later struggled to adapt their operations to foreign markets. In addition, we found that businesses that operated informally (without being officially registered) were less successful in exporting their products. However, we also found that businesses could overcome these challenges if their managers had relevant experience and adapted well to new circumstances. Our research contributes to understanding how businesses from emerging markets can succeed in international markets. We show how businesses can overcome the disadvantages of entering international markets late by having experienced managers and being able to adapt quickly. This study sets the path for future research in this area
Tensile failure mechanisms in additively manufactured brittle/ductile UV-curable resins and their nanocomposites with superior strength
No full textThis paper investigates the mechanical performance of two different types of UV-cured resin types with significantly different mechanical responses when reinforced with nanoparticles having different characteristics. To achieve that, it employed stereolithography (SLA) by a desktop scale printer to manufacture tension and open-hole tension (OHT) tests specimens according to ASTM D638 testing standards. OHT samples contained a circular hole of 1 mm radius that was printed. A highly ductile resin grade and a brittle resin grade were employed as the matrix phase, whereas nano-scaled Al2O3 (metal oxide) and SiO2 particles were used as nano inclusions in 1 and 5 wt. %. A detailed fractographic analysis is then performed to identify and classify the active failure modes in specimen failure for each case. For ductile-grade resins, tensile failure primarily occurs due to CL(Core layer)-interface separation during yielding, followed by either interfacial crack propagation or tensile failure of building blocks (BB) forming the core layers. Notably, the D-SiO₂-5 nanocomposite prevented CL-interface crack formation, allowing individual BB failure, while D-Al₂O₃ composites significantly increased tensile strength (60–70%) by resisting interface-related failure modes, making D-grade resins promising for further property tuning studies. The failure of brittle-grade nanocomposites was primarily driven by interfacial crack propagation between BBs and the coalescence of these cracks, with strengthening relying on nanoparticle-induced crack deflection without additional cracking. While B-Al₂O₃ composites achieved minor tensile strength increases (10–20%) through crack deflection, they introduced micro-cracks within BBs, whereas B-SiO₂ nanocomposites exhibited the highest tensile strength without this issue, making them the most effective among the investigated cases. In overall, a comprehensive document discussing the development of strength and deformation in nanocomposite SLA samples is presented