Theoretical Work Research Articles

Emotion expression salience and racially biased weapon identification: A diffusion modeling approach.

Racial stereotypes are commonly activated by informational cues that are detectable in people's faces. Here, we used a sequential priming task to examine whether and how the salience of emotion (angry/scowling vs. happy/smiling expressions) or apparent race (Black vs. White) information in male face primes shapes racially biased weapon identification (gun vs. tool) decisions. In two experiments (Ntotal = 546) using two different manipulations of facial information salience, racial bias in weapon identification was weaker when the salience of emotion expression versus race was heightened. Using diffusion decision modeling, we tested competing accounts of the cognitive mechanism by which the salience of facial information moderates this behavioral effect. Consistent support emerged for an initial bias account, whereby the decision process began closer to the "gun" response upon seeing faces of Black versus White men, and this racially biased shift in the starting position was weaker when emotion versus race information was salient. We discuss these results vis-à-vis prior empirical and theoretical work on how facial information salience moderates racial bias in decision-making.

Group vocal composition and decision-making during roost finding in Spix's disk-winged bats.

Theoretical work suggests that having many informed individuals within social groups can promote efficient resource location. However, it may also give rise to group fragmentation if members fail to reach consensus on their direction of movement. In this study, we investigate whether the number of informed individuals, exemplified by bats emitting calls from different roosts, influences group cohesion in Spix's disk-winged bats (Thyroptera tricolor). Additionally, we explore the role of signal reliability, quantified through signalling rates, in group consensus on where to roost. These bats use contact calls to announce the location of a roost site and recruit conspecifics. The groups they form exhibit high levels of cohesion and consist of both vocal and non-vocal bats, with vocal behaviour being consistent over time. Our findings revealed that an increase in the number of roosts broadcasting calls is strongly associated with the likelihood of groups fragmenting among multiple roosts. Additionally, we found that a majority of group members enter the roost with higher calling rates. This phenomenon can mitigate the risk of group fragmentation, as bats emitting more calls may contribute to greater group consensus on roosting locations, thereby reducing the likelihood of individuals separating and enhancing overall group cohesion. Our results highlight the potential costs of having too many information producers for group coordination, despite their established role in finding critical resources. This article is part of the theme issue 'The power of sound: unravelling how acoustic communication shapes group dynamics'.

All-optical source size and emittance measurements of laser-accelerated electron beams

Novel schemes for generating ultralow emittance electron beams have been developed in past years and promise compact particle sources with excellent beam quality suitable for future high-energy physics experiments and free-electron lasers. Recent theoretical work has proposed a laser-based method capable of resolving emittances in the sub 0.1 mm mrad regime by modulating the electron phase space ponderomotively. Here we present the first experimental demonstration of this scheme using a laser wakefield accelerator. The observed emittance and source size are consistent with published values. We also show calculations demonstrating that tight bounds on the upper limit for emittance and source size can be derived from the “laser-grating” method even in the presence of low signal to noise and uncertainty in laser-grating parameters. Published by the American Physical Society 2024

Tensions in the pursuit of equal opportunities: A case study of an innovative secondary school

AbstractEqual opportunities in the context of education can be interpreted as ensuring equitable access to certain kinds of education (e.g. an academic track) or as equal opportunities to lead a fulfilling life regardless of the educational route followed (e.g. vocational or academic). These interpretations are in tension: the former implies a hierarchy where some forms of education are considered better than others, whereas the latter requires that they are all considered valuable. This paper presents a case study of a secondary school in the Netherlands that pursued both interpretations of equal opportunities and made systemic reforms to achieve this. Building on interviews, focus groups and participant observation with students, staff and management, the paper analyses the tension these actors experienced between the two interpretations of equal opportunities. It is argued that this stems from a societal context that endorses the first interpretation of equal opportunities but aligns less with the second interpretation. The analysis shows that individual institutions like schools have limited power to shift narratives surrounding educational tracks, especially when these do not align with prevailing trends in society. Additionally, the paper underlines the value of applying analysis of different interpretations of equal opportunities, which is usually undertaken by theoretical work, to empirical data.

Adsorption of Diffusing Tracers, Apparent Tortuosity, and Application to Mesoporous Silica.

The apparent tortuosity due to adsorption of diffusing tracers in a porous material is determined by a scaling approach and is used to analyze recent data on LiCl and alkane diffusion in mesoporous silica. The slope of the adsorption isotherm at small loadings is written as β = qA/qG, where qA is the adsorption-desorption ratio and qG = ϵ/(as) - 1 is a geometrical factor depending on the range a of the tracer-wall interaction, the porosity ϵ, and the specific surface area s. The adsorption leads to a decrease of effective diffusion coefficient, which is quantified by multiplying the geometrical tortuosity factor τgeom by an apparent tortuosity factor τapp. In wide pores or when the adsorption barrier is high, τapp = β + 1, as obtained in previous works, but in narrow pores there is an additional contribution from frequent adsorption-desorption transitions. These results are obtained in media with parallel pores of constant cross sections, where the ratio between the effective pore width ϵ/s and the actual width is ≈0.25. Applications to mesoporous silica samples are justified by the small deviations from this ideal ratio. In the analysis of alkane self-diffusion data, the fractions of adsorbed molecules predicted in a recent theoretical work are used to estimate τgeom of the silica samples, which is ≫1 only in the sample with the narrowest pores (nominal 3 nm). The application of the model to Li+ ion diffusion leads to similar values of τgeom and to a difference of energy barriers of desorption and adsorption for those ions of ∼0.06 eV. Comparatively, alkane self-diffusion provides the correct order of magnitude of τgeom, with adsorption playing a less important role, whereas adsorption effects on Li+ diffusion are much more important.

Enhancement of superconducting transition temperature and exotic stoichiometries in the Lu−S system under high pressure

Binary metal sulfides are a potential family of materials for exploring high Tc superconductors under high pressure. In this work, we study the crystal structures, electronic structures, and superconducting properties of the Lu-S system in the pressure range from 0 to 200 GPa, combining crystal structure predictions with calculations. We predict 15 unique structures, encompassing seven unidentified stoichiometries. Within the S-rich structures, the formation of S atom cages is beneficial for superconductivity, with the superconducting transition temperature 25.86 and 25.30 K for LuS6−C2/m at 70 GPa and LuS6−R−3m at 90 GPa, respectively. With the Lu/(Lu+S) ratio increases, the Lu-d electrons participate more in the electronic properties at the Fermi energy, resulting in the coexistence of superconductivity and topological nontriviality of LuS2−Cmca, as well as the superconductivity of predicted Lu-rich compounds. Our calculation is helpful for understanding the exotic properties in the transition metal sulfides system under high pressure, providing the possibility of designing alternative superconductors for future experimental and theoretical works. Published by the American Physical Society 2024

Scientific realism, scientific practice, and science communication: An empirical investigation of academics and science communicators

We argue that the societal consequences of the scientific realism debate, in the context of science-to-public communication are often overlooked and careful theorizing about it needs further empirical groundwork. As such, we conducted a survey experiment with 130 academics (from physics, chemistry, and biology) and 137 science communicators. We provided them with an 11-item questionnaire probing their views of scientific realism and related concepts. Contra theoretical expectations, we find that (a) science communicators are generally more inclined towards scientific antirealism when compared to scientists in the same academic fields, though both groups show an inclination towards realism and (b) academics who engage in more theoretical work are not less (or more) realist than experimentalists. Lastly, (c), we fail to find differences with respect to selective realism but find that science communicators are significantly less epistemically voluntarist compared to their academic counterparts. Overall, our results provide first empirical evidence on the views of scientists and science communicators on scientific realism, with some results running contra to the theoretical expectations, opening up new empirical and theoretical research directions.

Transient analysis of a bulk stream queue with arbitrarily distributed arrival intervals

We study the classical infinite buffer single server queueing model with renewal input of customers in batches of random size, having arbitrarily distributed arrival intervals and exponentially distributed service times. Using the technique of supplementary variable and shift operator we derive closed form expression of the time dependent system content distribution in terms of its Laplace transform. The analysis is mainly based on the root-finding technique of the non-linear characteristic equation in terms of the Laplace transform variable. Additionally, using asymptotic properties of Laplace transform, we deduce the corresponding steady-state distribution. We discuss some special cases of the model, thus providing an alternative approach in deriving the transient distribution. We further evaluate certain performance measures and present extensive numerical examples in tabular and graphical form to illustrate the applicability of our theoretical work. The effect of system parameters, interarrival time distribution and traffic intensity on the system behavior is also demonstrated.

How do labour market conditions explain the development of mental health over the life-course? a conceptual integration of the ecological model with life-course epidemiology in an integrative review of results from the Northern Swedish Cohort

BackgroundThe aim of this study was to contribute to the theoretical development within the field of labour market effects on mental health during life by integrating Bronfenbrenner’s ecological model with mainly earlier theoretical work on life-course theory.MethodsAn integrative review was performed of all 52 publications about labour market conditions in relation to mental health from the longitudinal Northern Swedish Cohort study. Inductive and deductive qualitative content analysis were performed in relation to Bronfenbrenner’s ecological framework combined with life-course theories.ResultsThe following nine themes were identified: 1. Macroeconomic recession impairs mental health among young people. 2. The mental health effects on individuals of youth unemployment seem rather insensitive to recession. 3. Small but consistent negative effect of neighbourhood unemployment and other work-related disadvantaged on individuals’ mental health over life. 4. Youth unemployment becomes embodied as scars of mental ill-health over life. 5. Weak labour market attachment impairs mental health over life. 6. Bidirectional relations between health and weak labour market attachment over life. 7. Macrolevel structures are of importance for how labour market position cause poor health. 8. Unequal gender relations at work impacts negatively on mental health. 9. The agency to improve health over life in dyadic relations. Unemployment in society permeates from the macrolevel into the exolevel, defined by Bronfenbrenner as for example the labour market of parents or partners or the neighbourhood into the settings closest to the individual (the micro- and mesolevel) and affects the relations between the work, family, and leisure spheres of the individual. Neighbourhood unemployment leads to poor health among those who live there, independent of their employment status. Individuals’ exposure to unemployment and temporary employment leads to poorer mental health over the life-course. Temporal dimensions were identified and combined with Bronfenbrenner levels into a contextual life-course modelConclusionCombining the ecosocial theory with life-course theories provides a framework for understanding the embodiment of work-related mental health over life. The labour market conditions surrounding the individual are of crucial importance for the embodiment of mental health over life, at the same time as individual agency can be health promoting. Mental health can be improved by societal efforts in regulations of the labour market.

Concentration Quenching of Fluorescence Decay Kinetics of Molecular Systems.

Fluorescence concentration quenching occurs when increasing molecular concentration of fluorophores results in a decreasing fluorescence quantum yield. Even though this phenomenon has been studied for decades, its mechanisms and signatures are not yet fully understood. The complexity of the problem arises due to energy migration and trapping in huge networks of molecules. Most of the available theoretical work focuses on integral quantities like fluorescence quantum yield and mean excitation lifetime. In this work, we present a numerical study of the fluorescence decay kinetics of three-dimensional and two-dimensional molecular systems. We investigate the differences arising from the variations in models of trap formations. We also analyze the influence of the molecular orientations to the fluorescence decay kinetics. We compare our results to the well-known analytical models and discuss their ranges of validity. Our findings suggest that the analytical models can provide inspiration for different ways of approximating the fluorescence kinetics, yet more detailed analysis of the experimental data should be done by comparison with numerical simulations.

Correcting the record: Phonetic potential of primate vocal tracts and the legacy of Philip Lieberman (1934-2022).

The phonetic potential of nonhuman primate vocal tracts has been the subject of considerable contention in recent literature. Here, the work of Philip Lieberman (1934-2022) is considered at length, and two research papers-both purported challenges to Lieberman's theoretical work-and a review of Lieberman's scientific legacy are critically examined. I argue that various aspects of Lieberman's research have been consistently misinterpreted in the literature. A paper by Fitch et al.overestimates the would-be "speech-ready"capacities of a rhesus macaque, and the data presented nonetheless supports Lieberman's principal position-that nonhuman primates cannot articulate the full extent of human speech sounds. The suggestion that no vocal anatomical evolution was necessary for the evolution of human speech (as spoken by all normally developing humans) is not supported by phonetic or anatomical data. The second challenge, by Boë et al., attributes vowel-like qualities of baboon calls to articulatory capacities based on audio data; I argue that such "protovocalic"properties likely result from disparate articulatory maneuvers compared to human speakers. A review of Lieberman's scientific legacy by Boë et al.ascribes a view of speech evolution (which the authors term "laryngeal descent theory") to Lieberman, which contradicts his writings. The present article documents a pattern of incorrect interpretations of Lieberman's theoretical work in recent literature. Finally, the apparent trend of vowel-like formant dispersions in great ape vocalization literature is discussed with regard to Lieberman's theoretical work. The review concludes that the "Lieberman account"of primate vocal tract phonetic capacities remains supported by research: the ready articulation of fully human speech reflects species-unique anatomy.

Sperm competition favours intermediate sperm size in a hermaphrodite.

Sperm competition is a potent mechanism of post-copulatory sexual selection that has been found to shape reproductive morphologies and behaviours in promiscuous animals. Especially sperm size has been argued to evolve in response to sperm competition through its effect on sperm longevity, sperm motility, the ability to displace competing sperm and ultimately fertilization success. Additionally, sperm size has been observed to co-evolve with female reproductive morphology. Theoretical work predicts that sperm competition may select for longer sperm but may also favour shorter sperm if sperm size trades off with number. In this study, we studied the relationship between sperm size and post-mating success in the free-living flatworm, Macrostomum lignano. Specifically, we used inbred isolines of M. lignano that varied in sperm size to investigate how sperm size translated into the ability of worms to transfer and deposit sperm in a mating partner. Our results revealed a hump-shaped relationship with individuals producing sperm of intermediate size having highest sperm competitiveness. This finding broadens our understanding of the evolution of sperm morphology by providing empirical support for stabilizing selection on sperm size under sperm competition.

The binding energy distribution of H2S: why it is not the major sulphur reservoir of the interstellar ices

Abstract Despite hydrogen sulfide (H2S) has been predicted to be the major reservoir of S-bearing species on the icy mantles of interstellar grains, no solid H2S has been detected so far. A crucial parameter that governs whether or not a species remains frozen onto the grain mantles is its binding energy (BE). We present a new computational study of the H2S BE on a large amorphous water ice surface, constituted by 200 water molecules. The resulting H2S BE distribution ranges from 57 K (0.5 kJ/mol) to 2406 K (20.0 kJ/mol), with the average μ = 984 K (8.2 kJ/mol). We discuss the reasons why the low bound of the newly computed BE distribution, which testifies to the very weak interaction of H2S with the ice surface, has never been found by previous theoretical or experimental works before. In addition, the low H2S BEs may also explain why frozen H2S is not detected in interstellar ices. Following previous molecular dynamics studies that show that the energy of reactions occurring on ice surfaces is quickly absorbed by the water molecules of the ice and conservatively assuming that 10% of the HS + H → H2S formation energy (-369.5 kJ/mol) is left to the newly formed H2S, its energy is more than twice the largest BE and 5 times the average BE and, hence, H2S will most likely leave the water surface.

The average transmitted wave in random particulate materials

Abstract Microwave remote sensing is significantly altered when passing through clouds or dense ice. This phenomenon isn't unique to microwaves; for instance, ultrasound is also disrupted when traversing through heterogeneous tissues. Understanding the average transmission in particle-filled environments is central to improve data extraction or even to create materials that can selectively block or absorb certain wave frequencies. Most methods that calculate the average transmitted field assume that it satisfies a wave equation with a complex effective wavenumber. However, recent theoretical work has predicted more than one effective wave propagating even in a material which is statistically isotropic and for scalar waves. In this work we provide the first clear evidence of these predicted multiple effective waves by using high-fidelity Monte-Carlo simulations that do not make any statistical assumptions. To achieve this, it was necessary to fill in a missing link in the theory for particulate materials: we prove that the incident wave does not propagate within the material, which is usually taken as an assumption called the Ewald-Oseen extinction theorem. By proving this we conclude that the extinction length - the distance it takes for the incident wave to be extinct - is equal to the correlation length between the particles.

Modeling the dispersion measure—redshift relation for fast radio bursts

This theoretical work investigates different models to predict the redshift of fast radio bursts (FRBs) from their observed dispersion measure (DM) and other reported properties. We performed an extended revision of the FRBs with confirmed galaxy hosts in the literature and built the most updated catalog to date. With this sample of FRBs, we propose four models that relate the DM and z: a linear trend (inspired by the Macquart relation), a log-parabolic function, a power law, and an interpolation for DM that includes z and the position of the host galaxy of the transient. The latter model has the highest success rate according to the metrics implemented: likelihood, median of the z difference, and the Akaike and Bayesian information criteria. Although the performance of model D is closely followed by the power law and linear models, the former has the advantage of accounting for anisotropies in the dispersion measure due to the angular coordinates. Conversely, the log-parabolic formula performs poorly in this task but provides a good prediction for FRBs with low DM at a low redshift. Additionally, we use the reported galaxy properties of the hosts to establish a connection between the observed DM with the star formation rate (SFR) and stellar mass (Ms) of the galaxies where the FRBs reside. In both cases, we find a weak correlation. Although the studied correlations are well-motivated, the sample of FRBs is not statistically significant enough to draw solid conclusions in this second part of our work. With the advent of new facilities devoted to studying the localization and nature of these transients, we will get access to new data that will enrich the proposed models and give us hints on the astrophysical origin and evolution of FRBs.

Giancarlo De Carlo’s Realistic Utopia

To seek a possible means to navigate the apparent divergence between participation and criticality in architecture, this paper returns to the notion of the “realistic utopia,” developed by one of the leading early exponents of participation, the Italian architect, urbanist, writer and educator, Giancarlo De Carlo. Through a close reading of De Carlo’s principal theoretical works on participation, in this paper it is argued that the realistic utopia offers a distinct conception of the interaction between architectural objects, the processes by which they are formed and the societal structures which frame this formation. It shows that beyond being a means to understand the multi-directional relationship between architecture and society, the realistic utopia offers a conceptual tool to aid action within the complex set of forces at work in this relationship. In this way, it locates the realistic utopia as something of importance beyond an assessment of the work of De Carlo, or even the broader project of participation he fostered, and is here opened up for renewed use by practitioners today.

Preventing Sexual Harm in Nightlife Settings: A Scoping Review.

Sexual harm within nightlife settings is a pervasive global concern; however, little is known about the nature of available interventions. The current study aims to review the literature on the nature and effectiveness of nightlife-related sexual harm interventions. A systematic literature search of six databases was conducted to identify records that were published between 1970 and June 2023 and reported approaches that aimed to reduce or prevent nightlife-related sexual harm. Records were included if they theorized, discussed, or evaluated an intervention, prevention or response strategy; however, individual safety strategies were excluded. Results were categorized according to intervention type. Thirty-five peer-reviewed journal articles and 16 gray literature records were identified. The most common nightlife-related sexual harm intervention strategies covered by the literature included targeted policies, laws, and regulations, bystander interventions, and awareness-raising campaigns. Literature in the area is increasing, with the majority of the articles (77.1%) being published in the previous six years; however, there are very few interventions that have been critically evaluated (22.9%). Promising areas for intervention include targeted alcohol regulations (e.g., lockout policies), venue-level policies, and environmental interventions. However, an increase in rigorous evaluative practices is urgently required to ensure future interventions are based on sound theoretical work and empirical evidence.

Experimental Study of the Reaction of OH Radicals with Carbonyl Sulfide between 365 and 960 K: Kinetics and Products

Reaction OH + OCS ® products (1) has been studied in a discharge–flow reactor combined with modulated molecular beam mass spectrometry. The reaction rate constant has been determined under pseudo-first-order conditions through monitoring OH decays in a high excess of OCS: k1 = (2.35 ± 0.25) × 10−12 exp(−(2144 ± 56)/T) cm3 molecule−1 s−1 at T = 365–960 K (the uncertainties represent precision at the 2σ level, the total 2σ relative uncertainty including statistical and systematic errors on the rate constant being 20% at all temperatures). The rate constant of reaction (1) was found to be similar at a total helium pressure of 1, 2, and 8 torr at around 500 K. The SH radical was identified as the primary product of the reaction, and its yield was determined to be about 100% at T = 500 and 750 K. The kinetic and mechanistic data from the present study are compared to previous experimental and theoretical work.

Size, shape, and dimension effects on the melting temperature of metallic nanocrystals

Melting is the most common phenomenon in nature and one of the most important properties of metallic materials. Exploring the size D, shape α, and dimension d effects on the melting temperature T m of nanocrystals is of great significance for the design, fabrication, and application of quantum devices. In this work, by redefining the critical diameter D 0 and introducing shape factor α, a unified model without any adjustable parameters has been developed to describe the T m(D, α, d) function. The model is compared with the available experimental and simulation data of Cu, Pd, In, Pb, Au, Ag, and Ni nanocrystals and other theoretical works, and a consistent agreement is obtained, which verifies the accuracy of the prediction. This model is also compared with other theoretical works, and we find that it agrees well with Lu’s model, while the BOLS method underestimates the melting point. This work not only gives a new perspective on the relationship between size, shape, dimension, and melting temperature but also provides theoretical guidance for the design and optimization of low-dimensional quantum devices.

Proposing a Conceptual Framework for the Study of SME Success in Service Industry: An Appraisal of Theories

The objective of this article is to review the extant literature on the factors contributing to the success of Small and Medium-sized Enterprises (SMEs) operating within the service sector. SMEs constitute a significant component of all economies, with the service sector comprising the largest segment of SMEs in most countries. Given the diverse nature of SMEs within the service sector, this appraisal of theoretical work may help researchers and practitioners alike to have a better understanding of SME success factors to inform strategies not only in this sector but also for other sectors of the economy, including but not limited to the industrial sector, financial sector, and manufacturing sector.