Using ensembles of decision trees to predict transport mode choice decisions: Effects on predictive success and uncertainty estimates

The application of activity-based models of travel demand to planning practice has triggered interest in issues that potentially improve the accuracy and/or usefulness of model forecasts. The limited knowledge of uncertainty propagation in complex stochastic model systems has put uncertainty analysis high on the research agenda to differentiate between simulation error and policy effects. Focusing on transport mode choice, this paper draws attention to the use of model ensembles, which has hardly been explored in travel demand forecasting. Prior studies predicting transport mode choice has typically relied on a single equation, relating observed transport mode choices to a set of personal and contextual variables. The estimated single model is then assumed to apply to all individuals. This paper explores the idea of replacing a single equation/representation with an ensemble of model predictions, using the decision tree formalism. Potentially, ensembles better capture the notion that travellers may use different heuristics in their transport mode decisions. The aim of the study is to investigate whether the use of a model ensemble of different decision heuristics will reduce the error/uncertainty in predicting transport mode decisions. Results of the study, conducted in the Rotterdam region, The Netherlands, suggest that the accuracy of predicting transport mode choice is improved, albeit non-monotonically, with increasing ensemble size. Simultaneously, the uncertainty related to these predictions is decreasing. Finally, it is shown that the importance of the selected explanatory variables co-varies with ensemble size. Estimation results tend to become stable in this study with an ensemble size of approximately 20 decision trees

Car Allocation between Household Heads in Car Deficient Households: A Decision Model

This paper considers car allocation choice behaviour in car-deficient households explicitly in the context of an activity-scheduling process, focusing on work activities. A decision tree induction method is applied to derive a decision tree for the car allocation decision in automobile deficient households using a large travel-and-activity diary data set recently collected in the Netherlands. The results show a satisfactory improvement in goodness of fit of the decision tree model compared to a null model. Overall, the probability of males getting the car for work is considerably higher than that of female in many condition settings. However, activity schedule, spatial and socio-economic variables appear to have an influence as well. An analysis of impacts of condition variables on car allocation decisions reveals that socio-economic variables have only a limited impact, whereas attributes of the transportation and land-use system have a relatively big impact. The propensity of men driving a car to the work place is higher than that of women. However, the relative accessibility of the work location by bike compared to car appears to have a relatively large influence on who gets the car for work. Household income and presence of children also appear to have significant effects

Analysis of Built Environment Influence on Pedestrian route choice behavior in Dutch Design Week using GPS Data

Visitors not only have specific destinations targeting the Dutch Design Week (DDW) exhibitions distributed all over the city, but also visit the city in between exhibition activities. The mixed environment makes modeling behavior of DDW visitors more complex than shoppers and tourisms only. This research pays special attention to the influence of built environment on pedestrian route choice. The built environment includes building and transportation infrastructure. GPS tracking data and social demographic information were collected during the event. Multinomial logit model and path size logit model are used to analysis route choice behavior. The results show that some built environment factors have significant influence on route choice. Shops are more attractive for aged visitors. Females prefer shorter routes more. In big event, the alternative routes with more sharing links could increase the possibility to choose

Activin is produced by rat Sertoli cells in vitro and can act as an autocrine regulator of Sertoli cell function

Regulation of androgen receptor (AR) mRNA expression was studied in Sertoli cells and peritubular myoid cells isolated from immature rat testis, and in the lymph node carcinoma cell line derived from a human prostate (LNCaP). Addition of dibutyryl-cyclic AMP (dbcAMP) to Sertoli cell cultures resulted in a rapid transient decrease in AR mRNA expression (5 h), which was followed by a gradual increase in AR mRNA expression (24-72 h). This effect of dbcAMP mimicked follicle-stimulating hormone (FSH) action. In peritubular myoid cells, there was only a moderate but prolonged decrease during incubation in the presence of dbcAMP, and in LNCaP cells no effect of dbcAMP on AR mRNA expression was observed. When Sertoli cells or peritubular myoid cells were cultured in the presence of androgens, AR mRNA expression in these cell types did not change. This is in contrast to LNCaP cells, that showed a marked reduction of AR mRNA expression during androgen treatment. In the present experiments, transcriptional regulation of AR gene expression in Sertoli cells and LNCaP cells was also examined. Freshly isolated Sertoli cell clusters were transfected with a series of luciferase reporter gene constructs, driven by the AR promoter. It was found that addition of dbcAMP to the transfected Sertoli cells resulted in a small but consistent increase in reporter gene expression (which was interpreted as resulting from AR promoter activity); a construct that only contained the AR 5' untranslated region of the cDNA sequence did not show such a regulation. The same constructs, transfected into LNCaP cells, did not show any transcriptional down-regulation when the synthetic androgen R1881 was added to the cell cultures. A nuclear transcription elongation experiment (run-on), however, demonstrated that androgen-induced AR mRNA down-regulation in LNCaP cells resulted from an inhibition of AR gene transcription. The present results indicate that in Sertoli cells and LNCaP cells, hormonal effects on AR gene transcription play a role in regulation of AR expression. However, AR gene transcription in these cells is differentially regulated

Засади транскрибування китайської лексики українською мовою

Статтю присвячено проблемі уніфікації написання китайських географічних назв, власних імен та реалій українською мовою. Основним об’єктом дослідження є здатність української мови відтворювати китайські звуки. У статті розглянуто досвід транскрибування китайських слів засобами латинської та кириличної графіки, що важливо для формулювання основних принципів транскрипції з китайської на українську мову. Таких принципів у статті виділено чотири та розглянуто труднощі, які виникають під час їх застосування в процесі транскрибування. Відзначено, що ці труднощі можуть виявлятися або на рівні складу, або на рівні слова. Для вирішення проблем першого рівня, автор додає до статті таблицю складів-відповідників для китайської та української мов. А для уніфікації написання на другому рівні автор пропонує використовувати апостроф у випадку необхідності позначити межі складу, та відмінювати китайській імена й прізвища згідно норм української мови.Статья посвящается проблеме унификации написаний китайских географических названий, имен собственных и реалий в украинских текстах. Основным объектом исследования является способность украинского языка отображать китайские звуки. В статье рассматривается опыт транскрибирования китайских слов средствами латинской графики и кириллицы, что важно для формулирования основных принципов транскрипции с китайского языка на украинский. Таких принципов в статье выделено четыре, к тому же рассмотрены трудности, которые могут возникнуть при их применении в процессе транскрибирования. Отмечено, что эти трудности могут проявляться либо на уровне слога, либо на уровне слова. Для решения проблем первого уровня, автор прилагает к статье таблицу слоговых соответствий в китайском и украинском языках. А для унификации написаний на втором уровне, автор предлагает использовать апостроф в случае необходимости обозначить границы слогов, и склонять китайские имена и фамилии согласно нормам украинского языка.The article is devoted to the problem of unifying the ways to represent Chinese geographic names, persons’ names and cultural words in Ukrainian texts. The main object of the study is a capacity of Ukrainian language to reproduce Chinese sounds. It is proposed to consider an experience of transcription from Chinese into languages with Latin and Cyrillic alphabets, which is important to formulate main principles for the transcription from Chinese into Ukrainian. There are four main principles stated in the article for this pair of languages. It is also analyzed main difficulties, which occur in practice of using the transcription, based on these principles. The difficulties are divided into two groups: occurred on the level of syllable and occurred on the level of word. To solve problems on the former level, the author complicate the article with tables of Chinese syllables and there equivalents in Ukrainian. To unify writing on the latter level, the author proposes to use apostrophe if important to mark syllable bounds and change a word’s ending in Ukrainian texts according to the norms of Ukrainian grammar

Simultaneous Magneto-Optical Trapping of Two Lithium Isotopes

We confine 4 10^8 fermionic 6Li atoms simultaneously with 9 10^9 bosonic 7Li atoms in a magneto-optical trap based on an all-semiconductor laser system. We optimize the two-isotope sample for sympathetic evaporative cooling. This is an essential step towards the production of a quantum-degenerate gas of fermionic lithium atoms.Comment: 4 pages, 3 figure

Dense-core senile plaques in the Flemish variant of Alzheimer's disease are vasocentric

Alzheimer's disease (AD) is characterized by deposition of beta-amyloid (Abeta) in diffuse and senile plaques, and variably in vessels. Mutations in the Abeta-encoding region of the amyloid precursor protein (APP) gene are frequently associated with very severe forms of vascular Abeta deposition, sometimes also accompanied by AD pathology. We earlier described a Flemish APP (A692G) mutation causing a form of early-onset AD with a prominent cerebral amyloid angiopathy and unusually large senile plaque cores. The pathogenic basis of Flemish AD is unknown. By image and mass spectrometric Abeta analyses, we demonstrated that in contrast to other familial AD cases with predominant brain Abeta42, Flemish AD patients predominantly deposit Abeta40. On serial histological section analysis we further showed that the neuritic senile plaques in APP692 brains were centered on vessels. Of a total of 2400 senile plaque cores studied from various brain regions from three patients, 68% enclosed a vessel, whereas the remainder were associated with vascular walls. These observations were confirmed by electron