The extension of internal humidity levels beyond the soil surface facilitates mound expansion in Macrotermes

Termites in the genus Macrotermes construct large-scale soil mounds above their nests. The classic explanation for how termites coordinate their labour to build the mound, based on a putative cement pheromone, has recently been called into question. Here, we present evidence for an alternate interpretation based on sensing humidity. The high humidity characteristic of the mound's internal environment extends a short distance into the low-humidity external world, in a ‘bubble’ that can be disrupted by external factors like wind. Termites transport more soil mass into on-mound reservoirs when shielded from water loss through evaporation, and into experimental arenas when relative humidity is held at a high value. These results suggest that the interface between internal and external conditions may serve as a template for mound expansion, with workers moving freely within a zone of high humidity and depositing soil at its edge. Such deposition of additional moist soil will increase local humidity, in a feedback loop allowing the ‘interior’ zone to progress further outward and lead to mound expansion.

Impact of LED Color Temperatures on Perception Luminance in the Interior Zone of a Tunnel considering Fog Transmittance

LEDs are widely applied in highways and tunnels for their long life, low light attenuation, and being environment friendly in recent years. The influence of correlated color temperature (CCT) of LED on lighting safety has attracted people’s attention as the demand increased. In this paper, a calculation model of perception luminance of human eye considering mesopic vision and fog concentration was proposed. The influence of different CCTs on perception luminance of human eye under different levels of fog concentration and luminance was calculated and analyzed. The CCT of LED employed in the interior zone of a tunnel was selected based on the highest perception luminance in mesopic vision. Seven kinds of LEDs with different CCTs (3000–6500K) were applied in the experimental system with adjustable fog concentrations. The results showed that the main factors affecting visual perception are luminance and fog concentration. Higher luminance or lower fog concentration provides drivers with higher perception luminance. In contrast, although CCT has a less effect on perception luminance, LEDs with higher CCT (about 6500K) can provide higher perception luminance considering fog in mesopic vision. This paper provides technical support for tunnel lighting and guaranteeing traffic safety.

Study on Energy-saving Lighting Design Method for Interior Zone of High-altitude Highway Tunnel

In order to ensure the driving safety of high-altitude highway tunnel and effectively reduce the lighting cost, this paper adopts the method considering the influence of automobile headlights luminance which combines reaction time incremental theory at different altitudes and lighting design simulation calculation. The paper has studied the design pattern of high-altitude highway tunnel, which are dominated by fixed lighting and supplemented by automotive lighting. The results show that: to ensure driving safety, the luminance of the lighting design for interior zone of highway tunnel increases with the increasing altitude. Based on the supplementary lighting of automobile headlights, the lighting design standards for the interior zone of high-altitude highway tunnel(the altitude is 2000m, 3000m, 4000m, 5000m respectively) are 0.73cd/m2, 0.82cd/m2, 0.91cd/m2, 1.0cd/m2.

Simulation and Design Study for Interior Zone Luminance in Tunnel Lighting

An optimal solution for tunnel lighting designs was determined using a computer software. The road tunnel under construction 14481 m in length was selected in order to get an optimal design solution for tunnel lighting.The lighting, luminaries, and road parameters were changed and the resulting scenarios were examined in a simulation environment. The proposed approach can be applied for the illumination of interior zones in tunnels of 10 km or longer with significant reduction in energy consumption. The optimal luminance values that affect vision comfort in the tunnel were calculated in a simulation environment. As a result, the most economic lighting system and luminaries were chosen among solutions conforming to technical standards for luminance values.

Defining functional groups and their vulnerability to the edge effect in a peri-urban forest in Mexico City

SUMMARYThe expansion of human settlements and primary-sector activities (agriculture and forestry) has resulted in the fragmentation of forests, but the impacts of this are still poorly understood. We examined the effect of patch size on the presence of plant functional groups along an edge–interior gradient. Plant species were classified based on a two-way indicator species analysis in order to determine their establishment thresholds and vulnerability along the gradient, while detrended correspondence analyses and canonical correspondence analyses were performed to identify environmental gradients related to vegetation distribution. Two groups of plant species were recognized in all patch sizes: one commonly found towards the edge and the other in the interior zone. The incidence of these groups was correlated with environmental factors associated with the edge–interior gradient, mainly with humidity, soil moisture and light (canopy opening and global site factor) in the edge zone and with litter cover, depth of litter, slope and soil and air temperature in the interior zone. Identifying the species’ threshold responses to fragmentation is key, as they provide tools to prevent the potential local extinction of species.

Microfacies and the sedimentary environment of limestones at Hang Cay Ot, Binh An, Kien Luong, Kien Giang province

The limestones at Hang Cay Ot, Binh An commune, Ha Tien district, Kien Giang province belong to Ha Tien formation (Middle Permian). Based on microscopic studies, the limestones at Hang Cay Ot are packstone, grainstone and wackstone according to the Dunham carbonate rock’s classification, and four microfacies types are recognized. As a result, according to the modified Wilson model, three facies zones have been differentiated: (1) open marine platform interior zone, (2) platform-marin and shoal zone, (3) platform-marin reefs zone.