Relationship between specific (dis)utility and the frequency of driving a car

An interesting issue in contemporary travel behavior research is whether the transportation demand has to be considered purely derived from underlying activity patterns or whether a utility is also associated with traveling per se. In the latter case, substantial amendments of current planning models would be needed to represent this phenomenon adequately. Earlier research consistently gave evidence of the existence of this specific utility, but its quantification is hindered by a specific measurement problem because survey respondents tend to mingle the utility of traveling and the utility of reaching a destination. The present work defines a methodology to quantify the decrement in the specific utility of driving a car due to the presence of difficulties and self-limiting behaviors. This is in turn responsible for an alteration of driving frequency. A structural equation modeling technique is used for the analysis. The structural submodel represents the complex relationships between socio-economic variables, specific utility, and driving frequency. The measurement submodel defines the specific utility on the basis of reported self-evaluations concerning physical fitness and self-limiting behaviors while driving. An application of the method based on data collected in the 2002 National Transportation Availability and Use Survey is presented. The results show that the decrement of specific utility (which can be seen as a disutility) of driving a car has an important impact on the frequency of performing this activity compared with the derived utility that is customarily modeled through socioeconomic variables

Internet mobility survey sampling biases in measuring frequency of use of transport modes

We develop a quantitative analysis of the biases that arise when measuring trip frequencies for a general population through an online survey instrument. Data from a national official survey in Italy, concerning both mobility behaviors and skills in using computers and internet, have been deployed to assess differences in mobility levels between those that can answer a computer/internet survey and those that cannot. Positive correlations were found between ability in using ICT tools and trip frequencies. These latter are about 15% to 150% higher for the "ICT literate", according to the travel means under consideration. A Heckman sample selection model showed us that these biases have different explanations. People knowing how to use internet are different from the others in they car driving behavior due to a range of self-related factors. Conversely, public transport patterns of use are more similar between the two groups: the observed bias is mainly due to the fact of using internet in itself, which could for example lead to a more active lifestyle. Such distinction is of practical interest because it can help defining a method to correct these biases. According to our results, the overestimation of public transport frequency of use of an internet survey could be corrected by looking at the internet diffusion in the population. On the contrary, corrections for car driving frequencies are more complex and should be based on differences in attitudinal and personal characteristics between internet survey respondents and the remainder of the populatio

Innovative systems for the transportation disadvantaged: towards more efficient and operationally usable planning tools

When considering innovative forms of public transport for specific groups, such as demand responsive services, the challenge is to find a good balance between operational efficiency and 'user friendliness' of the scheduling algorithm even when specialized skills are not available. Regret insertion-based processes have shown their effectiveness in addressing this specific concern. We introduce a new class of hybrid regret measures to understand better why the behaviour of this kind of heuristic is superior to that of other insertion rules. Our analyses show the importance of keeping a good balance between short- and long-term strategies during the solution process. We also use this methodology to investigate the relationship between the number of vehicles needed and total distance covered - the key point of any cost analysis striving for greater efficiency. Against expectations, in most cases decreasing fleet size leads to savings in vehicle mileage, since the heuristic solution is still far from optimality

Desire to change one's multimodality and its relationship to the use of different transport means

Using data collected from French employees of a transportation institute and residents of the US San Francisco Bay Area, we operationalize a segmentation of mobility patterns based on objective, subjective, and desired amounts of mobility by various modes and overall. We especially focus on the degree of multimodality in an individual's current modal mix and desired changes to that mix through the use of a "multimodality index". The clusters that result showed some similarities and some differences across countries, where the latter are likely due to disparities in the sampling strategies and in the land use/transportation/cultural milieux. In both cases, however, the clusters have useful policy implications, enabling us, for example, to distinguish car users who might be inclined to reduce car use and increase transit use from those who are largely content with their current modal basket

Test of Host Sanction Hypothesis in Soybean Plants Co-inoculated with Nitrogen Fixing and Non-fixing Bradyrhizobium japonicum

Aims: We tested the proposed mechanism for potential sanctions, that the plant would reduce viability of non-fixing rhizobia inside nodules, performing viable Bradyrhizobium japonicum counts from co-occupied and single-occupied nodules in co-inoculated soybean plants. Study Design: Plants were co-inoculated with two strains of B. japonicum, a highly efficient nitrogen fixing wild-type strain BJD321, and the non-fixing, nifH mutant derivative A3, to produce co-occupied nodules as well as single-occupied nodules. Strain A3 lacks nitrogenase activity but shows similar infection and nodule formation levels respect to the wild-type. As the strains used are equivalent in competitive and nodulation abilities and only differ in the nitrogen fixation ability (by nitrogenase inactivation), and share the same plant, root and even nodule, we can assert that themechanism being tested is plant host sanction, and no other proposed mechanisms like partner choice. Place and Duration of Study: Nitrogen Metabolism Lab, Department of Soil Microbiology and Symbiotic Systems at Zaidín Experimental Station (CSIC State Agency, Granada, Spain). 2010- 2011. Methodology: Axenic seedlings of soybean (Glycine max) cultivar Williams were inoculated with 2 ml of bacterial suspension of BJD321 or A3 strains, alone or in 1:1 mixture and supplied with sterilized N free nutrient solution. Four weeks after inoculation plants of each inoculation treatment (BJD321 + A3, BJD321 only, A3 only) were harvested, nodules were counted and weighed and plated to determine rhizobial strain occupation and population. In the aerial part of plants, determinations of weight, N and C content were done. Results: Co-inoculated plants and plants only inoculated with the BJD321 strain showed a similar nitrogen fixation since they did not differ in dry weight, total N content and total C content. Plants with different inoculation treatments (BJD321 + A3, BJD321 only and A3 only) did not differ in nodule number. In co-inoculated plants, nodule occupation did not differ from the expected among strains (about 33% BJD321 + A3, BJD321 only and A3 only), and the weight of nodules occupied by both strains, BJD321 or A3 alone did not differ. In co-inoculated plants rhizobial viability did not differ between BJD321 and A3 strains, either comparing co-occupied nodules or single-occupied nodules. Nodule size and CFU of rhizobia inside nodules were not correlated, either in coinoculated plants or plants inoculated with BJD321 strain alone. Conclusion: We can conclude that in the soybean-B. japonicum system, plants facing the presence of fixing and non-fixing rhizobial strains do not sanction cheating and can perform as well as plants inoculated with the fixing strain alone.Fil: Marco, Diana Elizabeth. Universidad Nacional de Córdoba. Facultad de Cs.agropecuarias. Area de Producción Organica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Talbi, Chouhra. Universidad Nacional Autónoma de México; MéxicoFil: Bedmar, Eulogio. Consejo Superior de Investigaciones Científicas. Estación Experimental del Zaidín; Españ

Measuring the satisfaction of multimodal travelers for local transit services in different urban contexts

The importance of measuring customer satisfaction for a public transport service is apparent, even beyond more immediate marketing purposes. The present paper shows how satisfaction measures can be exploited to gain insights on the relationship between personal attitudes, transit use and urban context. We consider nine satisfaction measures of urban transit services, as expressed by a representative sample of Italian multimodal travelers (i.e. users of both private cars and public transport). We use correlations and correspondence analyses to show if and how each attribute is related to the levels of use of public transport, and how the relationship is affected by the urban context. Then we apply a recently developed method to combine ordinal variables into one score, by adapting it to work with large samples and with satisfaction measures which have a neutral point in the scale (i.e. ‘‘neither satisfied nor dissatisfied''). The resulting overall satisfaction levels and frequency of use were not correlated in our sample. We also found the highest satisfaction levels in smaller towns and the lowest ones in metropolitan cities. Since we focus on multimodal travelers, an interpretation paradigm is proposed according to which transit services must be well evaluated by car drivers in smaller towns in order to be considered a real alternative to cars. On the other hand, transit is more competitive on factual elements in larger cities, so that it can still be used by drivers, even if it is not very well evaluate

The Dopamine Hypothesis of Drug Addiction and Its Potential Therapeutic Value

Dopamine (DA) transmission is deeply affected by drugs of abuse, and alterations in DA function are involved in the various phases of drug addiction and potentially exploitable therapeutically. In particular, basic studies have documented a reduction in the electrophysiological activity of DA neurons in alcohol, opiate, cannabinoid, and other drug-dependent rats. Further, DA release in the Nucleus accumbens (Nacc) is decreased in virtually all drug-dependent rodents. In parallel, these studies are supported by increments in intracranial self stimulation (ICSS) thresholds during withdrawal from alcohol, nicotine, opiates, and other drugs of abuse, thereby suggesting a hypofunction of the neural substrate of ICSS. Accordingly, morphological evaluations fed into realistic computational analysis of the medium spiny neuron of the Nacc, post-synaptic counterpart of DA terminals, show profound changes in structure and function of the entire mesolimbic system. In line with these findings, human imaging studies have shown a reduction of dopamine receptors accompanied by a lesser release of endogenous DA in the ventral striatum of cocaine, heroin, and alcohol-dependent subjects, thereby offering visual proof of the “dopamine-impoverished” addicted human brain. The lasting reduction in physiological activity of the DA system leads to the idea that an increment in its activity, to restore pre-drug levels, may yield significant clinical improvements (reduction of craving, relapse, and drug-seeking/taking). In theory, it may be achieved pharmacologically and/or with novel interventions such as transcranial magnetic stimulation (TMS). Its anatomo-physiological rationale as a possible therapeutic aid in alcoholics and other addicts will be described and proposed as a theoretical framework to be subjected to experimental testing in human addicts

Making the "primary utility of travel" concept operational: A measurement model for the assessment of the intrinsic utility of reported trips

A growing body of research is casting light on the intrinsic utility of the traveling activity, something that seems not identifiable with the utility of performing activities at different locations. As a complement to previous speculative and empirical researches on this topic, the present study proposes a measurement model for the intrinsic, or primary utility of travel. A new definition of primary utility is proposed, keeping into account the users of different transportation modes, beyond car drivers. The model is then estimated on a dataset coming from a mixed behavioral and mobility survey, focusing on weekday trips of less than 50 km. Exploratory factor and item analyses define the set of structural equations used in a subsequent hierarchical confirmatory factor analysis. The rationale of this mixed approach is to adequately capture the complexity of the primary utility concept. The proposed model is found to fit the data satisfactorily well. The analysis of the resulting primary utility scores of the reported trips puts into evidence that intrinsic benefits from the traveling activity are not an exclusivity of car drivers and that they can be detected in work-related as well recreational trips