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There is a growing body of literature that recognizes the importance of mathematical modelling which deal with real world problems in mathematics school. The present study set out to investigate potential uses of the Hip Roof problem to introduce a mathematical modelling activity to Indonesian students. This study was exploratory and interpretative in nature. The Hip Roof problem was originally developed by the researcher and was assigned to six groups of undergraduate students enrolled at one public university in Jakarta, Indonesia. Test administration and interview were conducted to describe their work. The works were analyzed descriptively. The result indicates that the problem is feasible with undergraduate students and the participants of the study appreciate the problem included in school mathematics to enhance their ability to implement mathematics in their real life. In solving the problem, the participants used their personal mathematical knowledge.

Mitigation of the urban heat island (UHI) effect at the city-scale is investigated using the Weather Research and Forecasting (WRF) model in conjunction with the Princeton Urban Canopy Model (PUCM). Specifically, the cooling impacts of green roof and cool (white high-albedo) roof strategies over the Baltimore-Washington metropolitan area during a heat wave period (7 June-10 June 2008) are assessed using the optimal set-up of WRF-PUCM described in the companion paper by Li and Bou-Zeid (2014). Results indicate that the surface UHI effect (defined based on the urban-rural surface temperature difference) is reduced significantly more than the near-surface UHI effect (defined based on urban-rural 2 m air temperature difference) when these mitigation strategies are adopted. In addition, as the green and cool roof fractions increase, the surface and near-surface UHIs are reduced almost linearly. Green roofs with relatively abundant soil moisture have comparable effect in reducing the surface and near-surface UHIs to cool roofs with an albedo value of 0.7. Significant indirect effects are also observed for both green and cool roof strategies; mainly, the low-level advection of atmospheric moisture from rural areas into urban terrain is enhanced when the fraction of these roofs increases, thus increasing the humidity in urban areas. The additional benefits or penalties associated with modifications of the main physical determinants of green or cool roof performance are also investigated. For green roofs, when the soil moisture is increased by irrigation, additional cooling effect is obtained, especially when the 'unmanaged' soil moisture is low. The effects of changing the albedo of cool roofs are also substantial. These results also underline the capabilities of the WRF-PUCM framework to support detailed analysis and diagnosis of the UHI phenomenon, and of its different mitigation strategies.

Origami patterns, including the rigid origami patterns in which flat inflexible sheets are joined by creases, are primarily created for zero-thickness sheets. In order to apply them to fold structures such as roofs, solar panels, and space mirrors, for which thickness cannot be disregarded, various methods have been suggested. However, they generally involve adding materials to or offsetting panels away from the idealized sheet without altering the kinematic model used to simulate folding. We develop a comprehensive kinematic synthesis for rigid origami of thick panels that differs from the existing kinematic model but is capable of reproducing motions identical to that of zero-thickness origami. The approach, proven to be effective for typical origami, can be readily applied to fold real engineering structures.

A large body of literature is available on wound healing in humans. Nonetheless, a standardized ex vivo wound model without disruption of the dermal compartment has not been put forward with compelling justification. Here, we present a novel wound model based on application of negative pressure and its effects for epidermal regeneration and immune cell behaviour. Importantly, the basement membrane remained intact after blister roof removal and keratinocytes were absent in the wounded area. Upon six days of culture, the wound was covered with one to three-cell thick K14 + Ki67 + keratinocyte layers, indicating that proliferation and migration were involved in wound closure. After eight to twelve days, a multi-layered epidermis was formed expressing epidermal differentiation markers (K10, filaggrin, DSG-1, CDSN). Investigations about immune cell-specific manners revealed more T cells in the blister roof epidermis compared to normal epidermis. We identified several cell populations in blister roof epidermis and suction blister fluid that are absent in normal epidermis which correlated with their decrease in the dermis, indicating a dermal efflux upon negative pressure. Together, our model recapitulates the main features of epithelial wound regeneration, and can be applied for testing wound healing therapies and investigating underlying mechanisms.

Infrastructure-based heat reduction strategies can help cities adapt to high temperatures, but simulations of their cooling potential yield widely varying predictions. We systematically review 146 studies from 1987 to 2017 that conduct physically based numerical modelling of urban air temperature reduction resulting from green-blue infrastructure and reflective materials. Studies are grouped into two modelling scales: neighbourhood scale, building-resolving (i.e. microscale); and city scale, neighbourhood-resolving (i.e. mesoscale). Street tree cooling has primarily been assessed at the microscale, whereas mesoscale modelling has favoured reflective roof treatments, which are attributed to model physics limitations at each scale. We develop 25 criteria to assess contextualization and reliability of each study based on metadata reporting and methodological quality, respectively. Studies have shortcomings with respect to neighbourhood characterization, reporting areal coverages of heat mitigation implementations, evaluation of base case simulations, and evaluation of modelled physical processes relevant to heat reduction. To aid comparison among studies, we introduce two metrics: the albedo cooling effectiveness (ACE), and the vegetation cooling effectiveness (VCE). A sub-sample of 47 higher quality studies suggests that high reflectivity coatings or materials offer ≈0.2 °C–0.6 °C cooling per 0.10 neighbourhood albedo increase, and that trees yield ≈0.3 °C cooling per 0.10 canopy cover increase, for afternoon clear-sky summer conditions. VCE of low vegetation and green roofs varies more strongly between studies. Both ACE and VCE exhibit a striking dependence on model choice and model scale, particularly for albedo and roof-level implementations, suggesting that much of the variation of cooling magnitudes between studies may be attributed to model physics representation. We conclude that evaluation of the base case simulation is not a sufficient prerequisite for accurate simulation of heat mitigation strategy cooling. We identify a three-phase framework for assessment of the suitability of a numerical model for a heat mitigation experiment, which emphasizes assessment of urban canopy layer mixing and of the physical processes associated with the heat reduction implementation. Based on our findings, we include recommendations for optimal design and communication of urban heat mitigation simulation studies.

Natural features, settings, and processes in urban areas can help to reduce stress associated with urban life. In this and other ways, public health benefits from, street trees, green roofs, community gardens, parks and open spaces, and extensive connective pathways for walking and biking. Such urban design provisions can also yield ecological benefits, not only directly but also through the role they play in shaping attitudes toward the environment and environmental protection. Knowledge of the psychological benefits of nature experience supports efforts to better integrate nature into the architecture, infrastructure, and public spaces of urban areas.

Organic materials can exhibit high porosity, but the structures often collapse or decompose at high temperatures. Yamagishi et al. synthesized an aromatic molecule that bears a symmetrical outer shell of three dipyridylphenyl wedges and crystallized it from highly dielectric solvents. Porous crystals formed with complex pore-wall structures that resulted from labile C–H⋯N bonds and van der Waals forces. Despite the weakness of these interactions, the porous structure was stable up to 202°C and could be recovered after collapse by exposure to solvent vapor. Science , this issue p. 1242 An aromatic core-shell molecule forms thermally stable, structurally complex porous crystals in highly dielectric solvents. Here we report an anomalous porous molecular crystal built of C–H···N-bonded double-layered roof-floor components and wall components of a segregatively interdigitated architecture. This complicated porous structure consists of only one type of fully aromatic multijoint molecule carrying three identical dipyridylphenyl wedges. Despite its high symmetry, this molecule accomplishes difficult tasks by using two of its three wedges for roof-floor formation and using its other wedge for wall formation. Although a C–H···N bond is extremely labile, the porous crystal maintains its porosity until thermal breakdown of the C–H···N bonds at 202°C occurs, affording a nonporous polymorph. Though this nonporous crystal survives even at 325°C, it can retrieve the parent porosity under acetonitrile vapor. These findings show how one can translate simplicity into ultrahigh complexity.

Pterosaurs were the first vertebrates to evolve powered flight 1 and comprised one of the main evolutionary radiations in terrestrial ecosystems of the Mesozoic era (approximately 252–66 million years ago), but their origin has remained an unresolved enigma in palaeontology since the nineteenth century 2 – 4 . These flying reptiles have been hypothesized to be the close relatives of a wide variety of reptilian clades, including dinosaur relatives 2 – 8 , and there is still a major morphological gap between those forms and the oldest, unambiguous pterosaurs from the Upper Triassic series. Here, using recent discoveries of well-preserved cranial remains, microcomputed tomography scans of fragile skull bones (jaws, skull roofs and braincases) and reliably associated postcrania, we demonstrate that lagerpetids—a group of cursorial, non-volant dinosaur precursors—are the sister group of pterosaurs, sharing numerous synapomorphies across the entire skeleton. This finding substantially shortens the temporal and morphological gap between the oldest pterosaurs and their closest relatives and simultaneously strengthens the evidence that pterosaurs belong to the avian line of archosaurs. Neuroanatomical features related to the enhanced sensory abilities of pterosaurs 9 are already present in lagerpetids, which indicates that these features evolved before flight. Our evidence illuminates the first steps of the assembly of the pterosaur body plan, whose conquest of aerial space represents a remarkable morphofunctional innovation in vertebrate evolution. Lagerpetids, bipedal archosaurs that are thought to be related to dinosaurs, are instead a sister group to pterosaurs, and although they have no obvious flight adaptations they share numerous synapomorphies with pterosaurs across the entire skeleton.

As shallow coal resources are gradually depleted, resource exploitation extends from the shallow into the deep, where the mechanical properties of the coal rocks change significantly. To study the mechanical properties and mining-induced response characteristics of deep coal rocks. On a laboratory scale, laboratory tests and mining mechanics simulations were conducted on coal samples recovered from 1000 m or deeper using a rock mechanics testing system called MTS815 Flex Test GT. On the engineering scale, considering the roadway Ji-14-31050, buried in Pingdingshan Coal Mine No. 12 as the research base, four parameters—anchor bolt stress, borehole stress, roof displacement, and roadway convergence distortion—were monitored to study the mining-induced mechanical response characteristics of the coal rocks. The laboratory-scale study showed that the tensile strength and deformation of the deep coal rocks were generally small when destroyed; the tensile strength was in the range of 0.07–0.15 MPa, indicating low strength and high brittleness; the average compression strength of the coal rocks at 1000 m or deeper was 111.7 MPa, which was significantly greater than that of coal rocks at shallower depths. The axial strain and volumetric strain of the deep coal rocks were also greater than those of the shallow coal rocks, indicating significant plasticity. Under the conditions of pillarless mining, the axial deformation, lateral deformation, and volume deformation of deep coal samples all show a large deformation platform near the peak stress, corresponding to the area in which the volumetric deformation showed a trend of expansion; furthermore, the peak stress was significantly lower in this area. The study on the engineering scale showed the coal mining-affected area (approximately 70 m) along the mining direction of the Ji-14-31050 coal mining face with a depth of over 1000 m in the Pingdingshan No. 12 mine was obviously larger than that of the shallow coal seams. As the mining face advanced, the anchor bolt stress, the roof separation, and the roadway section deformation showed similar patterns of increasing variation. In an area 30-m away from the mining face, the supporting pressure peaked, and the anchoring stress, roof separation, and tunnel cross-sectional deformation all changed significantly, displaying the surging phenomenon. At the same time, the roadway sidewall deformation was significantly greater than the deformation between the roof and floor. Clearly, as the mining depth extended deeper, the mining-induced stress field became increasingly more intense, and the coal mining-affected area increased noticeably. Meanwhile, the surrounding rock deformation and roof separation increased significantly, making it more difficult to control the stability of the rocks surrounding the roadway. The results of this study can provide guidance for roadway support, engineering design and mining technology optimization when mining at 1000 m or deeper.

To explore the law of ground deformation from shallow-buried close-distance multi-seam mining, an observation station was built in the Bulianta Coal Mine to measure and record the periodic variation of related parameters about ground subsidence and surface cracks with the advancement of working face. From the data observed from the field, it can be found that, when lower seam mining, the ground subsidence above the previously mined area was deeper and steeper than that above the left pillar; besides, the influence scope of the former was larger than that of the latter. In terms of ground cracks, the ground cracks were formed ahead of the working face and developed rapidly during the period of the breakage of the immediate roof. Besides, the average interval of the ground cracks above the previous gob was 14.75 m, and still existed and hardly changed after the advancement of the working face; while that above the left pillar was 27.8 m and most of them were closed. In addition, when the advance rate of the working face was 12.8 m/day, the advance influence distance of the mining surface crack reached the minimum of 13.6 m. This finding is helpful for protecting the surficial environment in mining area during and after mining operations and is also of significance to conduct green mining in other mining areas.