Uncrowded Environments Research Articles

Expectations of Students from Classroom Rules: A Scenario Based Bayesian Network Analysis

Classroom rules are a fundamental aspect of classroom management and ensuring compliance with established rules is crucial. Previous research has shown that students often pay little attention to the development of classroom rules. This quantitative study aims to investigate the expectations that students have concerning classroom rules. To this end, a 4-point Likert scale questionnaire consisting of 30 items was administered to 356 secondary school students. The Bayesian Search method and expert opinion were used to obtain a Bayesian Network model. The findings of the study indicate that students expect rules to be determined at the beginning of the academic year, wish to be involved in the determination process, and prefer minimal changes to the rules. They also expect a limited number of rules and reinforcement from teachers for displaying desirable behavior. Additionally, the study found that students are more likely to adhere to classroom rules in a clean and uncrowded environment, and prefer that their parents are not informed about these rules. The results also suggest that increased adherence to classroom rules leads to increased class inclusion, while decreased adherence results in decreased class inclusion. Furthermore, the study found that adoption of classroom rules leads to increased in-class cohesion, while non-adoption results in decreased cohesion. These findings contribute to the existing body of knowledge concerning student expectations of classroom rules.

Step Attention: Sequential Pedestrian Trajectory Prediction

In this paper we propose a deep learning model, which we call step attention, for pedestrian trajectory prediction. The proposed model has a special architecture which consists of recurrent neural networks, convolutional neural networks, and an augmented attention mechanism. Rather than developing architectures to model factors that may affect the walking behavior, the proposed model learns trajectory patterns directly from input sequences. We evaluate the performance of the step attention model using TrajNet–a publicly available benchmark dataset collected from diverse real-world crowded scenarios. We compare the performance of step attention with three existing state-of-the-art algorithms, including social LSTM, social GAN, and occupancy LSTM on the TrajNet benchmark dataset. Our experiments show that the average displacement error (ADE) of step attention for a 4.8-seconds-long prediction horizon is about 0.53 m. The final displacement error (FDE) is 1.72 m. Both average and final displacement errors are favorable compared to the benchmark methods. We conduct a second set of experiments using data collected from a four-way intersection through roadside camera sensor platforms to study the effectiveness of the proposed model in uncrowded environments. On this dataset, the proposed model has an ADE of 0.74 m and a FDE of about 1.40 m for a 6-seconds-long prediction horizon. A complementary set of experiments is conducted to further investigate model performance in a real-world intersection. In these experiments, the model gains an ADE/FDE of 0.76/1.70 m. The proposed model also produces accurate prediction results on different scenarios composed of different walking patterns (e.g., straight and curvy) and different environments (e.g., sidewalk and street). The average displacement errors on all investigated datasets are within the length of a single step of an adult. The experiments also indicate that the displacement error grows almost linearly with the prediction horizon.

The Influence of Social Crowding on Consumer Creativity

The importance of consumer creativity is currently widely recognized, yet the examination of the influence of environmental elements on consumer creativity is still limited. Our research investigates the influence of social crowding on consumer creativity performance. While past research mainly focuses on extreme crowding conditions, our research examines the impact of a moderate level of social crowding, which is more commonly experienced in reality. From two lab experiments, our research shows that compared to consumers in crowded environments, consumers in uncrowded environments perform better on creativity tasks (e.g., designing promotion slogans and identifying solutions to problems). Furthermore, the effect of social crowding is mediated by approach motives. Consumers in an uncrowded (vs. crowded) environment are more likely to trigger approach-based motivation, which enhances their creativity performance. These findings extend our knowledge of social crowding and creativity and can help consumers and companies improve creativity performance in appropriate environments.

Using Bluetooth Low Energy for positioning systems within overcrowded environments: A real in-field evaluation

Bluetooth Low Energy (BLE) is a widely-used technology for short-range proximity and distance estimation. The existence of human bodies is proved to influence BLE signals. In this paper, the effect of overcrowdedness on the performance of BLE-based positioning systems is studied. Real experiments are conducted in places with large and small areas. Both proximity and location beacons are evaluated with different transmission powers. Compared to uncrowded environments, results show random, but often manageable, changes in the received signal strength and position estimation accuracy. The logarithmic path loss model is found unsuitable for small areas and its parameters are noticeably affected by the crowdedness. Location beacons are found more robust against the increase in crowdedness than proximity counterparts. For these location beacons, the overcrowdedness maximally changes the signal strength by 8.6 dBm, the coverage range by 24 m, the proximity estimation accuracy by 18%, and the distance estimation accuracy by 41%.

Management of biofloc concentrations as an ecological strategy for microbial control in intensive shrimp culture

This study investigated if the intensity of sedimentation through settling tanks modifies the bacterial community composition of biofloc systems and affects performance of shrimp. A 50-day trial, which was conducted with Pacific White Shrimp juveniles (2.6 g ± 0.0 g) stocked at a density of 906 shrimp m−3, evaluated two different biofloc concentrations, i.e., total suspended solids: T500 (~ 500 mg L−1) and T700 (~ 700 mg L−1). To characterize the bacterial community, 40 water samples were taken for high throughput 16S-rDNA amplicon sequencing. Water quality variables were statistically similar among treatments and remained within the appropriate range for shrimp growth. No significant difference in the performance of animals was observed between treatments. Shrimp survival was high in both treatments (~ 90%), but the coefficient of the variation was 5.5 times higher in T500 (11.5%) than that observed in the T700 (2.1%). Bacterial richness was higher in T700, and composition of the bacterial community was different from that of the T500. We argue that a higher intensity of sedimentation, which decreased the TSS level in the T500, promoted changes in the microenvironment of these tanks. This, in turn, affected the ecological state of the system by destabilizing the bacterial community and promoting proliferation of opportunistic species (e.g., Vibrio) in tanks with lower floc levels. The higher presence of opportunists is likely related to a reduction in microbial carrying capacity (CC) and an increase in substrate supply per microbial cell promoted by the higher floc removal. Under such conditions, fast-growing opportunistic r-strategists are favoured because they perform better in uncrowded environments with high resource availability per cell. Conversely, tanks with higher floc levels, closer to the CC, and thus with scarcer resources per cell, result in strong competition and selection of slow-growing competition specialists - the K-strategists. In conclusion, our results show that the control of floc levels can be an important strategy to obtain bacterial control and should be considered in management practices.

Using Virtual Reality to Study Subjective Time in Crowded Versus Uncrowded Environments.

Human density in different locations influences time estimation. In this article, we report three experiments investigating whether research in virtual reality (VR) environments would replicate this earlier finding. In our first experiment, 35 participants wore head-mounted VR displays and watched two videos showing a cityscape and a countryside. While watching each video, participants were asked to provide their perceptions of 30 seconds of time passage. Perceived time in the cityscape condition was longer than in the countryside condition. In our second experiment, 43 participants wore head-mounted VR displays and watched two videos showing a crowded and uncrowded Ikebukuro station. While watching these videos, participants were asked to provide their perceptions of 60 seconds of time passage. Perceived time in the crowded condition was longer relative to the uncrowded condition. In our third experiment, 21 participants wore head-mounted displays and watched two videos showing a crowded and uncrowded nature park. While watching the videos, participants were asked to provide their perceptions of 60 seconds of time passage. These repeated findings in VR environments of longer time perception in crowded versus uncrowded conditions were similar to data reported by who examined how location and human density affected subjective time in the real world. We discussed the implications of the VR tool in subjective time research and how people perceive and use VR environments in daily life.

The Infectiousness of Crowds: Crowding Experiences Are Amplified by Pathogen Threats.

People sometimes perceive social environments as unpleasantly crowded. Previous work has linked these experiences to incidental factors such as being hungry or hot and to the relevance of the social environment for an individual's current goals. Here, we demonstrate that crowding perceptions and evaluations also depend on specific, active threats for perceivers. Eight studies test whether infectious disease threats, which are associated with crowded conditions, increase such reactions. Across studies, pathogen threat made dense social environments seem more crowded and generated more negative affect toward these environments. These perceptions and negative feelings were more influenced by pathogen threat relative to other threats of physical danger. Finally, reactions to pathogen threat affected people's choice of crowded versus uncrowded environments to inhabit. This research suggests that interpretations of social environments depend on the unique threats and opportunities those environments afford to individuals.

Emergence of Life on Earth: A Physicochemical Jigsaw Puzzle.

We review physicochemical factors and processes that describe how cellular life can emerge from prebiotic chemical matter; they are: (1) prebiotic Earth is a multicomponent and multiphase reservoir of chemical compounds, to which (2) Earth-Moon rotations deliver two kinds of regular cycling energies: diurnal electromagnetic radiation and seawater tides. (3) Emerging colloidal phases cyclically nucleate and agglomerate in seawater and consolidate as geochemical sediments in tidal zones, creating a matrix of microspaces. (4) Some microspaces persist and retain memory from past cycles, and others re-dissolve and re-disperse back into the Earth's chemical reservoir. (5) Proto-metabolites and proto-biopolymers coevolve with and within persisting microspaces, where (6) Macromolecular crowding and other non-covalent molecular forces govern the evolution of hydrophilic, hydrophobic, and charged molecular surfaces. (7) The matrices of microspaces evolve into proto-biofilms of progenotes with rudimentary but evolving replication, transcription, and translation, enclosed in unstable cell envelopes. (8) Stabilization of cell envelopes 'crystallizes' bacteria-like genetics and metabolism with low horizontal gene transfer-life 'as we know it.' These factors and processes constitute the 'working pieces' of the jigsaw puzzle of life's emergence. They extend the concept of progenotes as the first proto-cellular life, connected backward in time to the cycling chemistries of the Earth-Moon planetary system, and forward to the ancient cell cycle of first bacteria-like organisms. Supra-macromolecular models of 'compartments first' are preferred: they facilitate macromolecular crowding-a key abiotic/biotic transition toward living states. Evolutionary models of metabolism or genetics 'first' could not have evolved in unconfined and uncrowded environments because of the diffusional drift to disorder mandated by the second law of thermodynamics.

Lateral spread of invasive Spartina alterniflora in uncrowded environments

We present a stochastic model of clonal growth in uncrowded environments and use it to study data of 7,536 clones from the invasion of Willapa Bay, Washington by the Atlantic cordgrass Spartina alterniflora. The model incorporates effects on clone growth of covariates, spatial autocorrelation, and temporal trends. The deterministic component of the model assumes that growth rate of a clone’s area is proportional to its perimeter, resulting in constant radial growth of the clone. The full stochastic model is built assuming that the fluctuations of radial growth increments (differences of square root-transformed areas) are normally distributed with constant variance. Graphical fit analysis with the density probability plot technique indicates that the stochastic model provides an excellent description of the S. alterniflora invasion. Variation in Spartina growth was significantly but weakly (5%) related to intertidal elevation, substrate type, year of survey, and the two-way interactions between these variables, suggesting that factors intrinsic to Spartina, along with localized high frequency noise, dominate the effects of larger scale abiotic factors on clone growth. Our model of clonal growth is potentially applicable to other systems with approximately circular plants or lichens.

Catalysis without a catalyst

Can two identical reactors with the same concentrations, under identical physical conditions, have reaction rates that differ by a factor of a thousand? A study now shows that, although not true in uncrowded environments, a reactant's starting point makes a large difference to reaction kinetics in identically crowded systems, such as cellular nuclei.

Sequence diversity and haplotype associations with phenotypic responses to crowding: GIGANTEA affects fruit set in Arabidopsis thaliana

Identifying the molecular genetic basis of intraspecific variation in quantitative traits promises to provide novel insight into their evolutionary history as well as genetic mechanisms of adaptation. In an attempt to identify genes responsible for natural variation in competitive responses in Arabidopsis thaliana, we examined DNA sequence diversity at seven loci previously identified as members of the phytochrome B signalling network. For one gene, GIGANTEA (GI), we detected significant haplotype structure. To test for GI haplogroup-phenotype associations, we genotyped 161 A. thaliana accessions at GI and censused the same accessions for total fruit set and the expression of three phenotypic traits (days to flowering, petiole length, and inflorescence height) in a greenhouse experiment where plants were grown in crowded and uncrowded environments. We detected a significant association between GI and total fruit set that resulted in a 14% difference in average fruit set among GI haplogroups. Given that fruit set is an important component of fitness in this species and given the magnitude of the effect, the question arises as to how variation at this locus is maintained. Our observation of frequent and significant epistasis between GI and background single nucleotide polymorphisms (SNP), where the fitness ranking of the GI allele either reverses or does not differ depending on the allele at the interacting SNP, suggests that epistatic selection may actively maintain or at least slow the loss of variation at GI. This result is particularly noteworthy in the light of the ongoing debate regarding the genetic underpinnings of phenotypic evolution and recent observations that epistasis for phenotypic traits and components of fitness is common in A. thaliana.

Mutation of algae from sensitivity to resistance against environmental selective agents: the ecological genetics of Dictyosphaerium chlorelloides (Chlorophyceae) under lethal doses of 3-(3,4-dichlorophenyl)-1, 1-dimethylurea herbicide

Residues contribute to water pollution and pose a challenge to microalgal populations because numerous contaminants are toxic to microalgae, even in the micromolar range. Adaptation of microalgae from herbicide sensitivity to herbicide resistance was analysed by an ecological genetic approach, using the unicellular alga Dictyosphaerium chlorelloides (Chlorophyceae) as an experimental model. A dose–effect study showed that the Malthusian parameter under conditions of r selection in an uncrowded environment and the carrying capacity under conditions of K selection in an crowded environment were both restricted even by low concentrations (< 1 μM) of 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (DCMU) herbicide. When a culture was treated with 50 μM DCMU, it cleared after a few days, as a result of destruction of sensitive cells by the herbicide. However, after further incubation for several days, the culture sometimes regained colour, owing to the growth of cell variants resistant to the herbicide. A fluctuation analysis was carried out to distinguish between (1) herbicide-resistant cells arising by direct and specific acquired adaptation in response to the herbicide and (2) herbicide-resistant cells arising by rare spontaneous mutations occurring randomly during replication of organisms prior to the incorporation of the herbicide. The fluctuation analysis unequivocally demonstrated that DCMU is not facilitating the development of DCMU-resistant cells; rather, we found that DCMU-resistant cells occur spontaneously by mutation in nonselective conditions prior to the incorporation of the herbicide (preselective mutations). The rate of spontaneous mutation from DCMU sensitivity to DCMU resistance was ∼ 2.2 × 10−6 mutants per cell division. Mutation was recurrent from a normal wild-type DCMU-sensitive allele to an DCMU-resistant allele, but such herbicide-resistant alleles were detrimental in terms of fitness in the absence of the herbicide. A competition experiment between wild-type DCMU-sensitive cells and DCMU-resistant mutants showed that, in small populations, the DCMU-resistant mutants are driven to extinction. The resistant variants are maintained in the absence of the herbicide as the result of a balance between new resistant cells arising by rare spontaneous mutation and resistant cells eliminated by natural selection. In our case, the average frequency of DCMU-resistant mutants in the absence of the DCMU is about five DCMU-resistant mutants per million cells. The results of our experimental model suggest that spontaneous mutation from herbicide sensitivity to herbicide resistance is sufficient in itself to assure the survival of microalgae populations in herbicide-contaminated environments when the population size is large.

Analysis of the relative abundance of different types of bacteria capable of toluene degradation in a compost biofilter.

A microbial community of a compost biofilter treating toluene vapors was investigated using serum-bottle assays and mineral-agar plates. Toluene was not consumed in the absence of oxygen. However, filter-bed extracts exposed to toluene vapor as the only carbon source produced distinct colony types (phenotypic groups) that were counted separately. Strains from each group were isolated and checked for toluene-degradation activity in serum bottles. Only 15% of colonies were true toluene degraders. This population was divided into 11 genotypic groups based on DNA fingerprints. Identification of a member of each group using 16S rRNA gene-sequence comparison showed that they belonged to seven genera: Acinetobacter, Azoarcus, Mycobacterium, Nevskia, Pseudomonas, Pseudonocardia and Rhodococcus. Together, members of the genera Pseudonocardia and Rhodococcus were 34 times more numerous than all the others. We hypothesized that these two organisms are K-strategists (adapted to a resource-restricted and crowded environment) and that the compost biofilter is a K-environment. This would explain why they are not outnumbered by faster growers like Pseudomonas or Acinetobacter species, which would be r-strategists (adapted to a resource-abundant and uncrowded environment).

Physiological, Cognitive, and Nonverbal Responses to Repeated Exposure to Crowding1

The present study testcd the hypotheses that crowded subjects would evidence higher levels of arousal than uncrowded subjects and that the arousal of crowded subjects would not habituate with the passage of time. In a laboratory setting, subjects were exposed three tinies over a 3‐week period to either crowding with physical contact or an uncrowded environment. A high degree of convergence in support of the experimental hypotheses was provided by behavioral, physiological, and self‐report measures. Crowded subjects were more physiologically aroused; rated by confederates to be more tense, uncomfortable, and annoyed; and reported more negative affect than uncrowded subjects. No evidence for habituation of. response to crowding was found.

The effects of crowding under different rearing conditions on emotionality and transfer of perceptual learning

To examine the effects of population density on emotionality and transfer of perceptual learning, albino rats were either preexposed to circles and triangles in a visually sparse environment or received no early experience with the to-be-discriminated shapes. Within each early experience condition, the animals were initially placed in either a crowded or uncrowded environment. Approximately 1 mo later, half of the rats under each population condition were shifted to the opposite population density condition, while the other half remained under their original condition. Analysis of the data indicated that (1) the animals uncrowded for the entire experiment were less emotional than animals crowded for the same length of time; (2) there was no difference in emotionality produced by 1 mo versus 2 mo of crowding; (3) animals uncrowded for 1 or more mo immediately after weaning were less emotional than animals crowded during this interval; (4) in general, animals preexposed to the to-be-discriminated forms learned the discrimination task in significantly fewer trials than did animals not receiving early stimulus preexposure; (5) animals that were crowded 1 mo immediately after weaning were poorer performers on the discrimination learning problem than were animals uncrowded during this same time period. Thus, the effects of population density on emotionality and transfer of perceptual learning were determined by population rearing conditions existing during the month immediately following weaning.