ABSTRACT
Over the last decade, urban logistics operations have changed significantly due to globalized production and distribution systems and expanding online shopping sales. On the one hand, goods are distributed on a greater scale through large-scale transportation infrastructure. On the other, exploding online shopping shipment has added another layer of complexity to urban logistics operations. Nowadays, instant home delivery has become prevalent. Provided that the geography, extent, and frequency of freight trip generation have completely changed, it can be assumed that the relationship between the development pattern characteristics and road safety outcomes has also changed, accordingly. Then, it is imperative that the spatial distribution of truck crashes, in conjunction with development pattern characteristics, is reexamined. As a Dallas-Fort Worth, TX metro area case study, this research examines whether the spatial distribution of truck crashes on city streets is different from that of other vehicle crashes and tests whether truck crashes have a unique association with development patterns. Results show that truck and passenger car crashes are distinguished in terms of how they are associated with urban density and employment sector compositions. The explanatory variables with significant and expected signs of relationship are VMT per network mile (exposure), intersection density, household income, % non-white, and % no high school diploma. Results indicate that the spatial heterogeneity in goods shipment intensity has strong implications for the variation in truck crash patterns. Results also call for a comprehensive reexamination of trucking activity in dense urban areas.
Subject(s)
Accidents, Traffic , Motor Vehicles , Humans , CommerceABSTRACT
Vertical jumping is the most important of the fundamental motor skills and has an important impact on children's health. A systematic study was conducted on the influence of vertical jumping on children's health and motor development patterns. In this study, the training and learning of vertical jumping were found to be effective in promoting children's development, especially in terms of height and muscle growth. Training interventions were used to determine the influence of age on children's learning of the correct vertical jumping motor pattern. Sex was found to have no influence on children's learning of vertical jumping. Although children were found to be able to learn the correct vertical jumping motor pattern, they could not reach a level of proficiency and intuitively apply the acquired skills to task completion. Cognitive ability was found to have a crucial effect on motor learning among children, especially when they faced various task constraints.
ABSTRACT
Urban growth and development caused by urbanization influence the urban heat island (UHI) phenomenon. With the rapid development of urbanization, China's major cities are facing more serious climate change problems, especially the UHI phenomenon. Proper planning and urban design of compact cities may improve the ventilation of street canyons and change the heat balance in the urban canopy and thus mitigate the UHI phenomenon. The aim of this study is to evaluate and discuss the mitigation of UHI with different types of land-use and land-cover (LUCC), as well as different development patterns for compact cities. To this end, we applied the weather research and forecasting model (WRF) with urban canopy model (WRF/UCM) in this study. To evaluate the impact of LUCC changes on the UHI, we set 2 cases based on land use and land cover statistical data from 1965 and 2008 of Wuhan. Also, to evaluate the impact of urban morphology changes on the UHI, we designed 2 hypothetical cases based on 2 different urban developing patterns, one is high rise case and another is high density case, to simulate the impact of urban morphology on the UHI. As for the results of this study, with different LUCC of 1965 and 2008, UHI intensity of Wuhan increased by 0.2⯰C-0.4⯰C in average. Moreover, the critical wind speed which can mitigate UHI of case 1965 is much lower than case 2008. With different urban morphology, the high-rise case may lead to lower UHI intensity at the pedestrian level due to the shading effects of high-rise buildings. However, the critical value of wind speed in the high-rise case was almost 1.5-2 times greater than that of the high-density case, which illustrates the reduced possibility of mitigating the UHI phenomenon for high-rise buildings in Wuhan City.
ABSTRACT
Objective: this study characterized the morphogenesis of Columba livia and proposed a table with 43 embryonic stages. The ontogeny of this species was divided into three phases: early, middle and late. Methods and Results: the early phase (stages 1-26) includes the final period of segmentation, gastrulation, neurulation and somitogenesis, organization of the extraembryonic membranes, and the initial formation of the major organic systems. The middle phase (stages 27-36) was characterized mainly by the growth of limbs and the organization of the autopodium, the formation and growth of the peak, and the development of integumentary annexes such as feather germs and leg scales. The late phase (stages 37-43) shows the overall embryo growth, the final organization of the pterilosis pattern and growth of feather germs, as well as final consumption of the yolk, and hatching. Conclusions: these results allow making comparisons with the proposed developmental events of Gallus gallus domesticus, highlighting similarities and differences in the ontogenetic sequence of both species. Therefore we propose some hypotheses about possible heterochronic events related to altricial-precocial developmental models.
Objetivo: en el presente trabajo se caracteriza la morfogénesis de Columba livia y se propone una tabla con 43 estadios embrionarios. La ontogenia de dicha especie fue dividida en tres etapas: temprana, media y tardía. Métodos y Resultados: la etapa temprana (estadios 1-26) incluye el periodo final de la segmentación, la gastrulación, neurulación y somitogénesis, la organización de las membranas extraembrionarias y la formación de los esbozos de los principales sistemas de órganos. La etapa media (estadios 27-36) se caracteriza principalmente por el crecimiento de los miembros y la organización del autopodio, la formación y crecimiento del pico y el desarrollo de los anexos tegumentarios como plumones y escamas de las patas. En la etapa tardía (estadios 37-43) se evidencia el crecimiento general del embrión, la organización final del patrón de pterilosis y crecimiento de plumones, como así también el consumo final del vitelo y la eclosión. Conclusiones: en base a los resultados obtenidos se realizan algunas comparaciones con respecto a los eventos del desarrollo propuestos para Gallus gallus domesticus, destacando semejanzas y diferencias en la secuencia ontogénetica de ambas especies. A partir de esto se plantean algunas hipótesis acerca de posibles eventos heterocrónicos relacionados con los modelos de desarrollo altricial-precoz.
Objetivo: no presente trabalho caracteriza-se a morfogênese de Columba livia, mediante uma tabela com 43 estágios embrionários. A ontogenia desta espécie foi dividida em três etapas: inicial, intermediária e final. Métodos y Resultados: a etapa inicial (estágios 1-26) incluiu o período final de segmentação, gastrulação, neurulação e somitogênese, organização das membranas extraembrionárias e formação dos esboços dos principais sistemas de órgãos. A etapa intermediária (estágios 27-36) foi caracterizada principalmente pelo crescimento dos membros e organização do autopódio, formação e crescimento do bico e desenvolvimento de anexos tegumentários como as penas e as escamas das patas. Na etapa tardia (estágios 37-43) foi caracterizada pelo crescimento geral do embrião, a organização final do padrão de pterilose e o padrão de crescimento das penas, assim como o consumo final do vitelo e eclosão. Conclusões: com base nos resultados obtidos, foram realizadas algumas comparações com respeito aos eventos do desenvolvimento proposto para Gallus gallus domesticus, destacando semelhanças e diferenças durante a sequência ontogenética de ambas espécies. A partir disso, algumas hipóteses são propostas acerca dos possíveis eventos heterocrônicos relacionados com os modelos de desenvolvimento altricial e precoce.
