Human-occupied Environments Research Articles

Field Study and Evaluation of KrCl* Far UV-C Device Capability for Inactivation of Phi6 Bacteriophage.

"Far UV-C" is an effective disinfection method that can be deployed in occupied areas. Commercially available Krypton Chloride (KrCl*) excimer lamps filtered to emit at 222 nm are effective in disinfecting pathogens and safe for human exposure up to an allowable threshold exposure, which is much longer than for conventional UV lamps emitting at 254 nm. Laboratory and controlled field testing of a filtered KrCl* excimer lamp for disinfection of a virus suspended in a thin film aqueous solution in an occupied office setting was conducted. Complete inactivation of almost 6 log (99.9999%) of Phi6 bacteriophage virus was achieved in ~20 min of exposure time in a field setting, equivalent to a dose of about 10 mJ cm-2 . The Phi6 inactivation rate constant for the field test results were not statistically different from laboratory values (P > 0.05, paired t-test). When positioned at 1 m distance from possible human exposure, this device can be used safely for almost 4.5 h of continuous direct exposure without any acute or long-term adverse health effects. This study illustrates the applicability and deployment of Far UV-C for pathogen reduction and can help in decision making for implementation of Far UV-C for disinfection in human-occupied environments.

Study on Musical Saw Bowing Motion with an Industrial Cooperative Humanoid Robot

The objective of this study was to automate the dual-arm coordination of an industrial humanoid robot when using a musical saw as a percussion instrument to produce a target sound. Especially, this report focuses on a humanoid robot with a characteristic of the real-time control to replace the traditional teaching and playback motion control. Meanwhile, it is assumed that the humanoid robot works in the environment that is near to a human being. To adapt in such situation, we aim to achieve the complex work using an advanced tool with its robot, as we perform a skillful motion. In the present report, we examine the performance of a musical saw using a bow because it is a kind of complex work using an unknown and advanced tool. Moreover, both the control method of the arm of the robot and the performance of the bow are discussed to construct a sound feedback control approach. As a result, it is demonstrated that the proposed approach has potential for both industrial and recreational applications of humanoid robots in human occupied environments.

Safe-by-design control for Euler–Lagrange systems

Safety-critical control is characterized as ensuring constraint satisfaction for a given dynamical system. Recent developments in zeroing control barrier functions (ZCBFs) have provided a framework for ensuring safety of a superlevel set of a single constraint function. Euler–Lagrange systems represent many real-world systems including robots and vehicles, which must abide by safety-regulations, especially for use in human-occupied environments. These safety regulations include state constraints (position and velocity) and input constraints that must be respected at all times. ZCBFs are valuable for satisfying system constraints for general nonlinear systems, however their construction to satisfy state and input constraints is not straightforward. Furthermore, the existing barrier function methods do not address the multiple state constraints that are required for safety of Euler–Lagrange systems. In this paper, we propose a methodology to construct multiple, non-conflicting control barrier functions for Euler–Lagrange systems subject to input constraints to satisfy safety regulations, while concurrently taking into account robustness margins and sampling-time effects. The proposed approach consists of a sampled-data controller and an algorithm for barrier function construction to enforce safety (i.e. satisfy position and velocity constraints). The proposed method is validated in simulation on a 2-DOF planar manipulator.

Exposure to artificial light at night accelerates but does not override latitude-dependent seasonal reproductive response in a North American songbird.

In the modern era of industrialization, illuminated nights have become a common defining feature of human-occupied environments, particularly cities. Artificial light at night (ALAN) imposes several known negative impacts on the neuroendocrine system, metabolism, and seasonal reproduction of species living in the wild. However, we know little about the impact of ALAN on populations of birds that either live year-round in the same location or move to different latitudes across seasons. To test whether ALAN has a differing impact on the reproductive timing of bird populations that winter in sympatry but breed at different latitudes, we monitored sedentary and migratory male dark-eyed juncos that were or were not exposed to low intensity (∼2.5±0.5 lux) ALAN. All groups were held in common conditions and day length was gradually increased to mimic natural day length changes (NDL). We assessed seasonal reproductive response from initiation to termination of the breeding cycle. As expected based on earlier research, the sedentary birds exhibited earlier gonadal recrudescence and terminated breeding later than the migratory birds. In addition, resident and migrant birds exposed to ALAN initiated gonadal recrudescence earlier and terminated reproductive events sooner as compared to their conspecifics experiencing NDL. Importantly, the difference in the reproductive timing of sedentary and migratory populations was maintained even when exposed to ALAN. This variation in the seasonal reproductive timing may likely have a genetic basis or be the result of early developmental effects imposed due to different light regimes related to the latitude of origin. This study reveals first that ALAN accelerated reproductive development across both migrants and residents and second that latitude-dependent variation in reproductive timing is maintained despite exposure to ALAN. These results corroborate a relationship between latitude, population, and reproductive timing while also revealing ALAN's impact on seasonal reproductive timing. This study reveals that, ALAN accelerated reproductive development but maintained latitude-dependent variation in reproductive timing across both migrant and resident bird populations.

Implementing Speed and Separation Monitoring in Collaborative Robot Workcells.

We provide an overview and guidance for the Speed and Separation Monitoring methodology as presented in the International Organization of Standardization's technical specification 15066 on collaborative robot safety. Such functionality is provided by external, intelligent observer systems integrated into a robotic workcell. The SSM minimum protective distance function equation is discussed in detail, with consideration for the input values, implementation specifications, and performance expectations. We provide analytical analyses and test results of the current equation, discuss considerations for implementing SSM in human-occupied environments, and provide directions for technological advancements toward standardization.

Stability of airborne microbes in the Louvre Museum over time

The microbial content of air has as yet been little described, despite its public health implications, and there remains a lack of environmental microbial data on airborne microflora in enclosed spaces. In this context, the aim of this study was to characterize the diversity and dynamics of airborne microorganisms in the Louvre Museum using high-throughput molecular tools and to underline the microbial signature of indoor air in this human-occupied environment. This microbial community was monitored for 6 month during occupied time. The quantitative results revealed variations in the concentrations of less than one logarithm, with average values of 10(3) and 10(4) Escherichia coli/Aspergillus fumigatus genome equivalent per m(3) for bacteria and fungi, respectively. Our observations highlight the stability of the indoor airborne bacterial diversity over time, while the corresponding eukaryote community was less stable. Bacterial diversity characterized by pyrosequencing 454 showed high diversity dominated by the Proteobacteria which represented 51.1%, 46.9%, and 38.4% of sequences, for each of the three air samples sequenced. A common bacterial diversity was underlined, corresponding to 58.4% of the sequences. The core species were belonging mostly to the Proteobacteria and Actinobacteria, and to the genus Paracoccus spp., Acinetobacter sp., Pseudomonas sp., Enhydrobacter sp., Sphingomonas sp., Staphylococcus sp., and Streptococcus sp.

Effect of Habitat Disturbance on Colony Productivity of the Social Wasp Mischocyttarus consimilis Zikán (Hymenoptera, Vespidae)

Social wasps are important elements of the fauna in a variety of environments, including human-modified environments. Evidence indicates that habitat quality affects the growth of colonies of social wasps in urban environments. This study investigated whether the colony productivity of the social wasp Mischocyttarus consimilis Zikán (Hymenoptera, Vespidae) is affected by loss habitat quality in human-occupied environment. Nests of M. consimilis were collected in forest and urban environment between January 2010 and June 2011. Only nests that reached the decline stage were sampled. As productivity parameters, we measured the total number of cells constructed, total number of adults produced and dry mass of the nests. Productivity was significantly lower in urban than in forest environment for all parameters analyzed. Habitat quality is probably the principal factor that contributed to the lower productivity in urban environment. In this type of environment, particularly where the study was conducted, the vegetation adjacent to the nesting sites was composed predominantly of grasses. Such habitats may have limited resources available, especially those resources used by the wasps for feeding the immature, such as larvae of other insects. That result suggests that human degradation of habitats negatively affects the final productivity of colonies of social wasps.

Human occupancy as a source of indoor airborne bacteria.

Exposure to specific airborne bacteria indoors is linked to infectious and noninfectious adverse health outcomes. However, the sources and origins of bacteria suspended in indoor air are not well understood. This study presents evidence for elevated concentrations of indoor airborne bacteria due to human occupancy, and investigates the sources of these bacteria. Samples were collected in a university classroom while occupied and when vacant. The total particle mass concentration, bacterial genome concentration, and bacterial phylogenetic populations were characterized in indoor, outdoor, and ventilation duct supply air, as well as in the dust of ventilation system filters and in floor dust. Occupancy increased the total aerosol mass and bacterial genome concentration in indoor air PM10 and PM2.5 size fractions, with an increase of nearly two orders of magnitude in airborne bacterial genome concentration in PM10. On a per mass basis, floor dust was enriched in bacterial genomes compared to airborne particles. Quantitative comparisons between bacterial populations in indoor air and potential sources suggest that resuspended floor dust is an important contributor to bacterial aerosol populations during occupancy. Experiments that controlled for resuspension from the floor implies that direct human shedding may also significantly impact the concentration of indoor airborne particles. The high content of bacteria specific to the skin, nostrils, and hair of humans found in indoor air and in floor dust indicates that floors are an important reservoir of human-associated bacteria, and that the direct particle shedding of desquamated skin cells and their subsequent resuspension strongly influenced the airborne bacteria population structure in this human-occupied environment. Inhalation exposure to microbes shed by other current or previous human occupants may occur in communal indoor environments.

Cooperative Object Transfer: Effect of Observing Different Part of the Object on the Cooperative Task Smoothness

Designing robots with human characteristics is a great challenge to researcher to fulfill the needs of robotic technology in human occupied environment. This research aims to enable a smooth and natural cooperative object transfer by a human hand and a robot manipulator mimicking the same task performed by two humans. Prior to the development of the human-robot system, investigation on characteristics which generate a smooth cooperative object transfer in a human-human system is crucial. Perceiving certain part of an object in transfer, acts as a medium for the exchange of object's motion information between subjects. We have investigated the effect of perceiving different parts of the object in transfer to the cooperative motion smoothness (smoothness is quantitatively evaluated using Minimum Jerk Model). The result suggests that observing the center part of the experimental object produced more frequent, a smooth and natural motion for task executed in leftward/rightward and upward/downward direction. Moreover, the center part was associated with less object rotation during smooth task in these directions. However, there is no significant difference between End and Center case for the same task executed in forward/backward direction. We also considered the importance of having information of cooperative task initiation signal and a target position to the cooperative task smoothness. Regardless of which part of the object being perceived, smoother task is frequently generated when both signals are available to both subjects. Although the effect of End and Center case may be significant in human-human system; in human-robot system, both cases should be further tested and evaluated.