1,776,867 research outputs found
The influence of bus service satisfaction on university students' mode choice
No full textThe purpose of this study was to determine the relationship between bus service satisfaction and the transport mode of choice among university students in Qatar. The degree of bus service satisfaction was collected directly from questionnaire surveys, in which university students were asked questions in relation to their satisfaction with the bus service they used and their transport mode of choice. These questions were categorized into three factors according to confirmatory factor analysis: service at bus stops, service of busses, and service of drivers. Furthermore, the students were asked which mode of transport they used given the choice between public and private transport. This study presents a structural equation model to determine how much bus service satisfaction affects people's decisions about their transport mode. The results from the analysis showed that three key factors-namely, service at bus stops, service of busses, and service of bus drivers-were strongly correlated to the mode of choice. In particular, the bus stop was strongly associated with ease of use, shade, cleanliness, safety, and crowdedness level, while the bus itself influenced reliability, travel time, and frequency. Complying with traffic laws and the driver's attitude were also important contributors to the level of bus service satisfaction. Ultimately, this study will be beneficial for policy/decision-makers. It will allow them to determine what needs to be accomplished to encourage people to use public transportation.Scopu
Commencement 2010: Senior Day author Khaled Hosseini
No full textIncludes descriptive metadata provided by producer in MP4 file: "Video @ Vanderbilt - Videos - Commencement 2010: Senior Day author Khaled Hosseini." By Vanderbilt University.Excerpts of commencement speach of Khaled Hosseini, author of the bestsellers The Kite Runner and A Thousand Splendid Suns. Hosseini spoke May 13 in a packed Memorial Gymnasium to 2010 graduates, their friends and family members.
“I ask you to seek out people in your community in need – to try not just to understand them, but to help them,” Hosseini said
Hurgadacin: A new steroid from Sinularia polydactyla
No full textHurgadacin (1), a 24,25-bishomo-26-methylenecholesterol was isolated from the soft coral Sinularia polydactyla, collected from the Red Sea, near Hurghada at the Egyptian coast. The new steroid 1 was isolated together with the closely related polyhydroxy steroids 24-methylenecholestane-3 beta,5 alpha,6 beta-triol (2) and 24-methylenecholestane-1 alpha,3 beta,5 alpha,6 beta,11 alpha-pentol (3), in addition to the sesquiterpene lactiflorenol (4) and the trinorcarotenolide acetate peridinin (5), The structures of the isolated compounds were confirmed by intensive studies of their 1D and 2D NMR spectra and mass data. The antimicrobial and cytotoxic activities of the soft coral extract and the corresponding constituents were evaluated against diverse pathogenic microorganisms and brine shrimps, respectively. (C) 2013 Elsevier Inc. All rights reserved.German Academic Exchange Service (DAAD
Assessment of the taxi service in Doha
No full textThis research focuses on passengers' satisfaction of the taxi service in Doha, Qatar. Qatar is a rich developing country where taxis are widely considered as a public transportation service due to the limited use of the existing bus service and the profoundly dominant use of private car by expats and Qatari locals. The main objective of this research is to identify the quality attributes of the current taxi service. A descriptive analysis relating the demographic, accessibility, and trip purposes to taxi users in general in Doha with overall service satisfaction was conducted. A Structural Equation Model was used to assess the taxi service attributes that influence the users' perceived satisfaction. Two models were developed: one was a relationship between the demographic and satisfaction of the users while the other was between the trip time and the satisfaction of the users. The first model supports the premise that income is the greatest attribute in the demographic followed by marital status, age, and occupation. On the other hand, the latter model demonstrated that waiting time is the most contributing variable among the times spent by taxi users followed by walking from work to a station, journey time, and walking from home to a station. 2016 Elsevier Ltd.Scopu
Comparison of SimTraffic and VISSIM Microscopic Traffic Simulation Tools in Modeling Roundabouts
No full textAbstract SimTraffic and VISSIM are two microscopic traffic simulation tools that are capable of modeling arterial roads with signalized intersections and roundabouts. This study compares the performance of the two simulation tools in modeling dual lane and triple lane roundabouts under different scenarios such as traffic volume, proportion of left turning movement, and proportion of trucks in the traffic flow. The two simulation tools did not show statistically significant difference in general. However; in the case of high traffic volumes, VISSIM showed higher average delays than those from SimTraffic compared to nearly identical results in the case of low traffic volumes
Zahramycins A-B, Two New Steroids from the Coral Sarcophyton trocheliophorum
No full textTwo new poly-hydroxy steroids, zahramycins A (1) and B (2), have been isolated from the polar fraction of the extract of the coral Sarcophyton trocheliophorum. Compound 1 was confirmed to bear an oxirane ring at C-5 and C-6, while 2 has a keto-hydroxy sterol structure. The known DNA primary metabolites uracil, thymine, adenine, uridine, 2'-deoxyuridine, and thymidine were also isolated and identified. Structures of the new sterols 1 and 2 were confirmed by NMR (H-1, C-13, H-1-H-1 COSY, HMQC, HMBC, and NOESY) spectroscopy, mass spectrometry (El, ESI, and HRMS), and by comparison with related structures. The antimicrobial and cytotoxic activities of compounds 1 and 2 along with that of the coral extract were also determined. Zahramycin B (2) showed high (15 mm) and moderate (12 mm) antibacterial activity against Staphylococcus aureus and Bacillus subtilis, and fungus Pythium ultimum (12 mm), while zahramycin A (1) and the crude extract of Sarcophyton trocheliophorum were inactive. Both steroids and the crude extract of Sarcophyton trocheliophorum showed no cytotoxicity.German Academic Exchange Service (DAAD
ChemInform Abstract: Zahramycins A—B, Two New Steroids from the Coral Sarcophyton trocheliophorum.
No full textSeven naphtho-γ-pyrones from the marine-derived fungus Alternaria alternata: structure elucidation and biological properties
No full textEight bioactive pyrone derivatives were identified from the culture of Alternaria alternata strain D2006, isolated from the marine soft coral Denderonephthya hemprichi, which was selected as its profound antimicrobial activities. The compounds were assigned as pyrophen (1), rubrofusarin B (2), fonsecin (3), and fonsecin B (5) beside to the four dimeric naphtho-γ-pyrones; aurasperone A (6), aurasperone B (7), aurasperone C (8), and aurasperone F (9). Structures of the isolated compounds were identified on the basis of 1D and 2D NMR spectroscopy and mass (EI, ESI, HRESI) data, and by comparison with the literature. Configuration of the four dimeric naphtho-γ-pyrones 6-9 was analyzed by CD spectra, exhibiting an identical stereochemistry
Bioactive Secondary Metabolites from a New Terrestrial Streptomyces sp. TN262
No full textDuring our search for Streptomyces spp. as new producers of bioactive secondary metabolites, the ethyl acetate extract of the new terrestrial Streptomyces isolate TN262 delivered eight antimicrobially active compounds. They were identified as 1-acetyl-beta-carboline (1), tryptophol (2), cineromycin B (3), 2,3-dihydrocineromycin B (4), cyclo-(tyrosylprolyl) (5), 3-(hydroxyacetyl)-indole (6), brevianamide F (7), and cis-cyclo-(l-prolyl-l-leucyl) (8). Three further metabolites were detected in the unpolar fractions using GC-MS and tentatively assigned as benzophenone (9), N-butyl-benzenesulfonamide (10), and hexanedioic acid-bis-(2-ethylhexyl) ester (11). This last compound is known as plasticizer derivatives, but it has never been described from natural sources. In this article, we describe the identification of the new Streptomyces sp. isolate TN262 using its cultural characteristics, the nucleotide sequence of the corresponding 16S rRNA gene and the phylogenetic analysis, followed by optimization, large-scale fermentation, isolation of the bioactive constituents, and determination of their structures. The biological activity of compounds (2), (3), (4), and those of the unpolar fractions was addressed as well.Tunisian-Egyptian project "MELLOULI/SHAABAN
Unusual pyranosyl cembranoid diterpene from Sarcophyton trocheliophorum
No full text9-Hydroxy-10,11-dehydro-sarcotrocheliol (1), a new pyrane-based cembranoid diterpene, has been isolated along with three other known compounds, namely, sarcotrocheliol acetate (2), (+)-sarcophytol A (3), and (-)-sarcophytonin A (4), from the organic extract of the soft coral Sarcophyton trocheliophorum. The chemical structures of compounds 1-4 were determined on the basis of their 1D and 2D NMR [H-1, C-13, H-1-H-1 correlation spectroscopy, heteronuclear multiple-quantum coherence, heteronuclear multiple-bond correlation, and nuclear Overhauser effect (NOE)] and mass spectra [electron ionization (EI), electrospray ionization, and high resolution mass spectrometry (HRMS)], and by comparison with related structures. The compounds 1-4 showed neither antimicrobial activity against 11 diverse tested microorganisms, nor cytotoxicity against brine shrimp, whereas the soft coral extract showed low cytotoxicity with a mortality rate of 1.7%.German Academic Exchange Service (DAAD
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