Rikkyo University

ABSTRACT Rising ambient temperatures increase health risks for outdoor workers; however, exertional heat exhaustion (EHE) among golf course workers remains underexplored. This study aimed to identify organizational, environmental, and personal factors associated with EHE-related symptoms. We conducted a retrospective case–control study of outdoor workers at 491 golf clubs in the Kanto region of Japan during the summer of 2025. Multivariate logistic regression identified independent risk and protective factors among 388 respondents, of whom 63.7% reported symptoms. Significant risk factors included high work intensity (adjusted odds ratio [AOR]: 4.40; p = 0.006), high humidity (AOR: 2.94; p = 0.012), and insufficient airflow (AOR: 2.03; p = 0.004). Protective factors included employer-provided heat education (AOR: 0.56; p = 0.025), sleep duration ≥6 h (AOR: 0.49; p = 0.001), and awareness of heat countermeasures (AOR: 0.42; p = 0.019). Scheduled breaks (AOR: 0.33; p = 0.008) and cooled break areas (AOR: 0.23; p < 0.001) were strongly associated with reduced risk, whereas shaded areas showed no significant association. Sunlight-shielding clothing (AOR: 0.52; p = 0.001) and cooling vests (AOR: 0.55; p = 0.018) were also protective. Effective risk reduction requires an integrated approach that combines workload moderation with functional apparel. This study provides the first quantitative evidence that organizational measures such as scheduled breaks and cooled break areas serve as effective protective factors in this occupational setting. Because key determinants often lie beyond individual control, proactive employer engagement and structural support are essential for ensuring worker safety.

The gut microbiome is a highly dynamic ecosystem, yet its temporal organization remains poorly understood because microbiome sampling is typically limited to sparse time points. To overcome this challenge, we developed an automated device to enable continuous fecal sampling from individual mice at minute- to hour-scale resolution. Combining full-length 16S rRNA amplicon sequencing with a limited set of long-read metagenomic references, we economically reconstructed genome- and function-level trajectories at high temporal resolution. Automated hourly sampling over 14 consecutive days enabled phase analysis, revealing collective synchronization of taxa partitioned by carbohydrate utilization strategies between day and night, with microbial taxa and functional genes showing reproducible temporal succession across mice. Perturbations such as cage transfer or antibiotic treatment transiently disrupted this functional synchronization, followed by recovery toward a coherent dynamical state. This system and analytic frameworks will enable us to explore rapid microbiome dynamics in health and disease.

In this study, we investigate the long-term evolution of the hierarchical structure and the stability of centrality correlations within Japan's cross-shareholding networks. Using a 23-year dataset (2001-2023) of all listed Japanese companies, we conducted network analysis of semi-annually constructed networks of industrial sectors based on strongly connected components. To examine hierarchical structures, centrality distributions, and their intercorrelations, we applied bow-tie decomposition, PageRank, and the Hypertext-Induced Topic Selection (HITS) algorithm. The largest strongly connected component (the core group) decreased over time, whereas the number of companies that held shares in core members without being held in return (IN) or that remained entirely disconnected increased. Correlations among network measures exhibited temporal stability. The in-strength was positively correlated with both PageRank (pa), computed from the original directed network, and an authority score, whereas the out-strength was positively correlated with the Reversed PageRank (ph) computed from the reversed network and the hub score. A negative correlation was observed between pa and ph. The correlation between in-strength and out-strength shifted from negative to positive around 2010, suggesting stronger cross-shareholding ties among companies. Most industries exhibited network-measure correlations similar to those observed in the overall network. In contrast, transportation equipment showed no significant correlation between in-strength and the corresponding pa, which suggests that firms were less influenced despite holding significant inbound voting rights. The relative ranking of network measures across industries remained stable over time. Banks consistently ranked low for in-strength and high for out-strength. Although their ph ranks remained high, their hub score ranks decreased. These findings, such as the declining influence of banks and the rising centrality of the information & communication and real estate sectors, suggest that traditional firm-level or short-term monitoring may overlook systemic ownership structures. Periodic network-based monitoring can help to identify resilient and structurally influential firms or clusters.

Abstract Observations of exoplanet transits by small satellites have gained increasing attention for reducing biases in the detection of long-period planets. However, no unambiguous detection of an exoplanet has yet been demonstrated using optics with apertures smaller than 60 mm. Here, we investigated the detectability of exoplanet transits using the telescopic Optical Navigation Camera (ONC-T) on board the Hayabusa2 spacecraft, which has an effective aperture of only 15 mm. We conducted transit observations of the hot Jupiters WASP-189 b and MASCARA-1 b, collecting data for 10 and four events, respectively. The transit signal was detected with a signal-to-noise ratio (SNR) of 13 for WASP-189 b and 8 for MASCARA-1 b for each event. Stacking all events improved the SNR to 40 and 16, respectively. The transit midtimes of each event were measured with a precision of 6 minutes and were consistent with Transiting Exoplanet Survey Satellite (TESS) data to within 2 minutes. The planet-to-star radius ratio was determined with an absolute precision of 0.004 (6% relative) and agreed with TESS results to within 0.002 (3% relative). The recent ONC-T and TESS data enabled an update to the planetary ephemerides. We report a 4 σ discrepancy between the updated orbital period of MASCARA-1 b and previously reported values. ONC-T sets a new record for the smallest-aperture instrument to detect an exoplanet transit from space, advancing the frontier of exoplanet science with miniature instrumentation. Our results suggest that optics as small as ONC-T may be capable of detecting transiting long-period Jupiters: a population that remains underrepresented in current surveys.

This study explores the evolution of emotionality across small-group dynamics during an additional language (L+) classroom discussion at a Japanese university. Founded in analysis of a videorecording of Japanese students’ interactions in their L+ English, it examines the ways in which emotional togetherness arises through the actions of four learners. By employing a unique multimodal (pictorial) transcription and a narrative interpretation, the study evocatively captures how verbal and embodied cues collaboratively facilitate the emotional resonance of the group. The authors identify three primary mechanisms underpinning this shared emotionality: (1) the shift from English to the students’ native (i.e. Japanese) conversational style, marked by shorter, mutually-elaborative turns and increased aizuchi (backchanneling); (2) the instantiation of mutual transportable identities in the form of shared knowledge of popular culture, and; (3) the role of laughter in both expressing and confirming shared emotionality. While these factors appear to play a key role in the emergent outcome, the study clearly supports the need for more contextualized, dynamic research into the localized emergence and functions of group emotionality in additional language learning.

Abstract We present results from coordinated multiwavelength observations of the microquasar SS 433, obtained with XRISM, optical telescopes (Seimei, LCO, Tomo-e Gozen, MITSuME), and the kSIRIUS near-infrared camera during 2024 April and 2025 March. The XRISM exposures amounted to ${\sim}200$ ks in 2024 and ~100 ks in 2025, corresponding to different combinations of orbital and precessional phases. With XRISM/Resolve’s high spectral resolution and large effective area, we clearly resolved numerous emission lines even in short time segments, achieving improved accuracy in Doppler-shift measurements relative to earlier observations. The simultaneously obtained X-ray and optical Doppler shifts suggest a possible tendency for the optical emission to lag slightly behind the X-rays. In the Resolve data, the Doppler shifts of the two jet components exhibited apparent asymmetries, with jet speeds fluctuating around ${\sim}0.26 \pm 0.01c$ in 2024 and ${\sim}0.30 \pm 0.01c$ in 2025. The velocity variations indicated modulations on a timescale of ~6.3 d, with a phase offset of about $-90^{\circ }$ relative to the nutation cycle. The observed line widths and flux of the approaching and receding jets appear consistent with the expected geometrical effects, indicating systematically larger line widths in the inner regions of the jets, as proposed by Shidatsu et al. (2025, PASJ, 77, 1313). Optical light curves show flares of ~400 s in 2024 and ~1600 s in 2025, with amplitudes up to ~15% during out-of-eclipse intervals, while the XRISM/Xtend light curves show no significant variability within the overlapping intervals and given the statistical uncertainties. Near-infrared photometry in 2024, obtained during an out-of-eclipse interval at a different epoch from the optical observations, showed no flare-like variability, and the X-ray band also remained constant within uncertainties. These coordinated observations provide a foundation for future XRISM studies aimed at probing the dynamical properties of the relativistic jets in SS 433.

A bstract We study configurations of two $$ \mathcal{N}=4 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>N</mml:mi> <mml:mo>=</mml:mo> <mml:mn>4</mml:mn> </mml:math> super Yang-Mills theories of unitary gauge groups connected by the BPS interfaces involving line operators. We find strong evidence of S-duality of the configurations as precise matching of the line defect half-indices which enumerate the BPS local operators at the junctions of the interfaces and line operators. The interface line defect half-indices are expressible as intriguing closed-form formulae involving the q -binomial coefficients and the principal specializations of the Schur functions.

Our primary objective in this essay is to constructively challenge the dominant formats and templates of publishing academic articles. We argue that predominant writing conventions not only restrict epistemic inclusivity but also maintain a traditional hierarchy between the written word and visual imagery, thereby undermining the potential of combining them in composing and learning from academic articles. By emphasizing an integration of words and visual imagery that goes beyond juxtaposition and illustration, we suggest eschewing mostly taken-for-granted dichotomies—abstract–particularistic, objective–subjective, and linear–spatial—prevalent in management journals. More specifically, we explore the transformative potential of integrating written text and visual elements in management learning and education through graphic articles. Thereby, we aim to enhance the relevance, inclusivity, and engagement of theoretical and empirical research for learning. Our call for action suggests a foundational change in conceiving of knowledge dissemination and consumption that unlocks the potential of appreciating a simultaneity of detail and abstraction, an entanglement of subjective and objective perspectives, and a departure from linear thinking. Contending that genuinely multimodal formats facilitate more holistic and active learning experiences, we advocate for an expanded toolkit that enriches the learning environment and empowers scholars and learners alike.

Purpose Previous research on accounting standard setting has focused on changes, with little research into how and why accounting standards persist. This study, therefore, focuses on the 2022 decision of the International Accounting Standards Board (IASB) to retain the existing impairment-only approach for its goodwill accounting standard. To understand the persistence of the standard, this study aims to investigate how the IASB addressed the same accounting issue in two different periods by examining changes in the interested parties’ arguments. It classifies and compares various arguments in the comment letters (CL) to consider the IASB’s legitimacy in terms of evidence-based policymaking. Design/methodology/approach This study classifies the interested parties’ arguments on goodwill accounting into several types. The classification enabled us to systematically compare the arguments in the two sets of CL submitted to the IASB’s official documents on goodwill accounting published in 2002 and 2020. In addition to categorizing arguments, this study conducted a text coding analysis for CL to supplement the results of categorization. Findings According to this study’s comparative analysis, the majority of CL were in favor of amortizing goodwill, and there was no conspicuous change in the overall proportion of various arguments in the two periods. Moreover, while conceptual arguments in the CL accounted for a larger proportion than those based on real economic effects, when focusing on the arguments relying on general accounting concepts, there was roughly an even split between arguments in favor of amortizing goodwill and those in favor of the impairment-only approach. These findings can be interpreted as one of the reasons why the IASB decided to retain the existing standards in 2022. Research limitations/implications This study’s comparative analysis through the detailed categorization of arguments in the CL provides a plausible interpretation of the IASB’s decision to retain the current standard for goodwill accounting, especially as those responsible for the accounting standard setting tend to place emphasis on the general conceptual arguments in their standard-setting process. The authors propose this viewpoint as a useful basis for theorizing the dynamics of accounting standards in the current trend of evidence-based standard setting. Originality/value This study focuses on the IASB’s accounting standard setting for goodwill over two periods, comparing stakeholder arguments to analyze the persistence of accounting standards. This study’s categorization of conceptual arguments as general and topic-specific is potentially valuable for future research into the politics of accounting standard setting.

Abstract Thermal infrared imaging by Longwave Infrared Camera (LIR) aboard JAXA's Venus orbiter Akatsuki has revealed horizontal structures of large‐scale topographic gravity waves (mountain waves) and thermal tides in the Venusian atmosphere. For quantitative analysis of these waves, we developed a radiative transfer model for an atmosphere perturbed by a gravity wave, which represents the mountain waves and the thermal tides in the equatorial region. Combining the infrared images with temperature profiles from the Akatsuki radio occultation, the cloud particle scale height, as well as the vertical wavelengths and growth rates of mountain waves and the semidiurnal thermal tide were determined. The cloud particle scale height around the cloud top was estimated to be approximately equal to the atmospheric scale height, indicating a vertically well‐mixed layer of the cloud particles near the cloud top in low latitudes. It was demonstrated that the brightness temperature amplitude observed by LIR is approximately half of the atmospheric temperature amplitude at the cloud top. The waves' impact on the mean flow above the cloud top was assessed by estimating their momentum deposition. The results show that mountain waves can induce an intense but localized deceleration of tens of m s −1 /day or larger above 80 km, while the semidiurnal tide provides a global and persistent deceleration that increases with height to reach the order of 1 m s −1 /day at 80 km. These results reveal two important but distinct mechanisms that contribute to the momentum budget of the Venusian upper atmosphere.