798 research outputs found
How Can Autonomous and Connected Vehicles, Electromobility, BRT, Hyperloop, Shared Use Mobility and Mobility-As-A-Service Shape Transport Futures for the Context of Smart Cities?
A smarter transport system that caters for social, economic and environmental sustainability
is arguably one of the most critical prerequisites for creating pathways to more livable urban futures.
This paper aims to provide a state-of-the-art analysis of a selection of mobility initiatives that may
dictate the future of urban transportation and make cities smarter. These are mechanisms either
recently introduced with encouraging uptake so far and much greater potential to contribute in a
shift to a better transport paradigm or still in an embryonic stage of their development and yet to be
embraced as powerful mechanisms that could change travel behaviour norms. Autonomous and
connected vehicles are set to revolutionise the urban landscape by allowing machines to take over
driving that for over a century has been exclusively a human activity, while electrical vehicles are
already helping decarbonising the transport sector. Bus rapid transit has been steadily reinventing
and rebranding conventional bus services revitalising the use of the humblest form of public
transport, while hyperloop is an entirely new, disruptive, and somewhat provocative, travel mode
proposition based on the use of sealed tube systems through which pods could travel free of air
resistance with speeds exceeding 1000 km/h. Shared use mobility mechanisms like car-sharing,
ride-sharing, ride-sourcing and public bicycles can help establishing a culture for using mobility
resources on an as-needed basis, while mobility-as-a-service will take this sharing culture a step
further, offering tailored mobility and trip planning packages that could entirely replace the need for
privately owned modes of transport
VLT/X-shooter spectroscopy of the afterglow of the Swift GRB 130606A: Chemical abundances and reionisation at
The reionisation of the Universe is thought to have ended around z~6, as
inferred from spectroscopy of distant bright background sources, such as
quasars (QSO) and gamma-ray burst (GRB) afterglows. Furthermore, spectroscopy
of a GRB afterglow provides insight in its host galaxy, which is often too dim
and distant to study otherwise. We present the high S/N VLT/X-shooter spectrum
of GRB130606A at z=5.913. We aim to measure the degree of ionisation of the IGM
between 5.02<z<5.84 and to study the chemical abundance pattern and dust
content of its host galaxy. We measured the flux decrement due to absorption at
Ly, and wavelength regions. The hydrogen and metal
absorption lines formed in the host galaxy were fitted with Voigt profiles to
obtain column densities. Our measurements of the Ly-forest optical
depth are consistent with previous measurements of QSOs, but have a much
smaller uncertainty. The analysis of the red damping wing yields a neutral
fraction (3). We obtain column density measurements of
several elements. The ionisation corrections due to the GRB is estimated to be
negligible (<0.03 dex), but larger corrections may apply due to the
pre-existing radiation field (up to 0.4 dex based on sub-DLA studies). Our
measurements confirm that the Universe is already predominantly ionised over
the redshift range probed in this work, but was slightly more neutral at z>5.6.
GRBs are useful probes of the ionisation state of the IGM in the early
Universe, but because of internal scatter we need a larger statistical sample
to draw robust conclusions. The high [Si/Fe] in the host can be due to dust
depletion, alpha-element enhancement, or a combination of both. The very high
value of [Al/Fe]=2.40+/-0.78 might connected to the stellar population history.
We estimate the host metallicity to be -1.7<[M/H]<-0.9 (2%-13% of solar).
(trunc.)Comment: 15 pages, 12 figure
Solar Twins and Solar Analogues in Galactic Surveys.
The Sun is a crucial benchmark for how we see the universe. Especially when it comes to the visible range of the spectrum, stars are commonly compared to the Sun, as it is the most thoroughly studied star.
In this work I have focussed on two aspects of the Sun and how it is used in modern astronomy. Firstly, I try to answer the question on how similar to the Sun another star can be. Given the limits of observations, we call a solar twin a star that has the same observed parameters as the Sun within its errors. These stars can be used as stand-in suns when doing observations, as normal night-time telescopes are not built to be pointed at the Sun. There have been many searches for these twins and every one of them provided not only information on how close to the Sun another star can be, but also helped us to understand the Sun itself. In my work I have selected _ 300 stars that are both photometrically and spectroscopically close to the Sun and found 22 solar twins, of which 17 were previously unknown and can therefore help the emerging picture on solar twins.
In my second research project I have used my full sample of 300 solar analogue stars to check the temperature and metallicity scale of stellar catalogue calibrations. My photometric sample was originally drawn from the Geneva-Copenhagen-Survey (Nordström et al. 2004; Holmberg et al. 2007, 2009) for which two alternative calibrations exist, i.e. GCS-III (Holmberg et al. 2009) and C11 (Casagrande et al. 2011). I used very high resolution spectra of solar analogues, and a new approach to test the two calibrations. I found a zero–point shift of order of +75 K and +0.10 dex in effective temperature and metallicity, respectively, in the GCS-III and therefore favour the C11 calibration, which found similar offsets. I then performed a spectroscopic analysis of the stars to derive effective temperatures and metallicities, and tested that they are well centred around the solar values.Aurinko on ratkaisevan tärkeä vertailukohta havainnoillemme universumista.Erityisesti visuaalisella alueella tähtiä verrataan yleisesti Aurinkoon,koska se on kaikkein parhaiten tutkittu tähti.
Tässä työssä olen keskittynyt kahteen aspektiin liittyen Aurinkoon ja sen käyttöön modernissa tähtitieteessä. Ensiksi yritän vastata kysymykseen, kuinka samanlainen Auringon kanssa toinen tähti voi olla. Johtuen havaintoihin liittyvistä rajoituksista, kutsumme Auringon kaksoseksi tähteä, jonka havaitut parametrit vastaavat Aurinkoa virheiden rajoissa. Näitä tähtiä voidaan käyttää Auringon sijaisina havaintoja tehdessä, koska normaaleja öisiin havaintoihin tarkoitettuja teleskooppeja ei ole rakennettu suunnattavaksi Aurinkoon. Useissa havainto-ohjelmissa on etsitty näitä kaksosia ja jokainen niistä on tuottanut lisää tietoa siitä miten samankaltainen Auringon kanssa toinen tähti voi olla, mutta myös auttanut ymmärtämään itse Aurinkoa. Työssäni olen valinnut 300 tähteä jotka ovat fotometrisesti ja spektroskooppisesti lähellä Aurinkoa ja löytänyt 22 Auringon kaksosta, joista 17 oli ennestään tuntemattomia ja jotka täten voivat auttaa kokonaiskuvaa Auringon kaksosista muodostumaan.
Toisessa tutkimusprojektissani olen käyttänyt 300 Auringon kaltaisen tähden kokonaisotostani tarkistaakseni lämpötila- ja metallisuusskaalojen kalibroinnin tähtikatalogeissa. Fotometrinen otantani on peräisin Geneva- Copenhagen-Survey -havainto-ohjelmasta (Nordström et al. 2004; Holmberg et al. 2007, 2009) jolle on olemassa kaksi vaihtoehtoista kalibrointia ts. GCS-III (Holmberg et al. 2009) ja C11 (Casagrande et al. 2011). Näiden kahden kalibroinnin testaamiseksi käytin Auringon kaltaisten tähtien hyvin korkean resoluution spektrejä sekä uutta lähestymistapaa. Löysin +75 K ja +0.10 dex siirtymän efektiivisissä lämpötiloissa ja metallisuudessa GCSIII nollapisteissä ja täten päädyn suosimaan C11 kalibrointia, joka löysi samankaltaisia poikkeamia. Tämän jälkeen suoritin spektroskooppisen analyysin otannan tähdille johtaakseni efektiiviset lämpötilat ja metallisuudet sekä testasin että ne ovat hyvin keskittyineitä Aurinkoa vastaaviin arvoihin.Siirretty Doriast
An R2R3 MYB transcription factor determines red petal colour in an Actinidia (kiwifruit) hybrid population
Background Red colour in kiwifruit results from the presence of anthocyanin pigments. Their expression, however, is complex, and varies among genotypes, species, tissues and environments. An understanding of the biosynthesis, physiology and genetics of the anthocyanins involved, and the control of their expression in different tissues, is required. A complex, the MBW complex, consisting of R2R3-MYB and bHLH transcription factors together with a WD-repeat protein, activates anthocyanin 3-O-galactosyltransferase (F3GT1) to produce anthocyanins. We examined the expression and genetic control of anthocyanins in flowers of Actinidia hybrid families segregating for red and white petal colour. Results Four inter-related backcross families between Actinidia chinensis Planch. var. chinensis and Actinidia eriantha Benth. were identified that segregated 1:1 for red or white petal colour. Flower pigments consisted of five known anthocyanins (two delphinidin-based and three cyanidin-based) and three unknowns. Intensity and hue differed in red petals from pale pink to deep magenta, and while intensity of colour increased with total concentration of anthocyanin, no association was found between any particular anthocyanin data and hue. Real time qPCR demonstrated that an R2R3 MYB, MYB110a, was expressed at significant levels in red-petalled progeny, but not in individuals with white petals. A microsatellite marker was developed that identified alleles that segregated with red petal colour, but not with ovary, stamen filament, or fruit flesh colour in these families. The marker mapped to chromosome 10 in Actinidia. The white petal phenotype was complemented by syringing Agrobacterium tumefaciens carrying Actinidia 35S::MYB110a into the petal tissue. Red pigments developed in white petals both with, and without, co-transformation with Actinidia bHLH partners. MYB110a was shown to directly activate Actinidia F3GT1 in transient assays. Conclusions The transcription factor, MYB110a, regulates anthocyanin production in petals in this hybrid population, but not in other flower tissues or mature fruit. The identification of delphinidin-based anthocyanins in these flowers provides candidates for colour enhancement in novel fruits
Match physical performance of elite female soccer players during international competition.
The purpose of the present study was to provide a detailed analysis of the physical demands of competitive international female soccer match-play. A total of 148 individual match observations were undertaken on 107 outfield players competing in competitive international matches during the 2011-2012 and 2012-2013 seasons, using a computerized tracking system (Prozone Sports Ltd., Leeds, England). Total distance (TD) and total high-speed running distances (THSR) were influenced by playing position, with central midfielders (CM) completing the highest (10985±706 m and 2882±500 m) and central defenders (CD) the lowest (9489±562 m and 1901±268 m) distances, respectively. Greater total very high-speed running (TVHSR) distances were completed when a team was without (399±143 m) compared to with (313±210 m) possession of the ball. The majority of sprints were over short distances with 76 % and 95 % being less than 5 m and 10 m, respectively. Between half reductions in physical performance were present for all variables, independent of playing position. The current study provides novel findings regarding the physical demands of different playing positions in competitive international female match-play and provides important insights for physical coaches preparing elite female players for competition
Flibanserin and 8‐OH‐DPAT Implicate Serotonin in Association between Female Marmoset Monkey Sexual Behavior and Changes in Pair‐Bond Quality
Introduction. Psychopathological origins of personally distressing, hypoactive sexual desire disorder (HSDD) in women are unknown, but are generally attributed to an inhibitory neural regulator, serotonin (5‐HT). Flibanserin, a 5‐HT 1A agonist and 5‐HT 2A antagonist, shows promise as a treatment for HSDD. Aim. To test the hypothesis that female marmoset sexual behavior is enhanced by flibanserin and diminished by 8‐OH‐DPAT, in order to evaluate the efficacy of serotonergic modulation of female sexual behavior in a pairmate social setting comparable to humans. Methods. Sexual and social behavior were examined in eight female marmoset monkeys receiving daily flibanserin (15 mg/kg), 8‐OH‐DPAT (0.1 mg/kg), or corresponding vehicle for 15–16 weeks in a counterbalanced, within‐subject design, while housed in long‐term, stable male–female pairs. Main Outcome Measures. Marmoset pairmate interactions, including sexual and social behavior, were scored during weeks 5–6 of daily flibanserin, 8‐OH‐DPAT or vehicle treatment. 24‐hour pharmacokinetic profiles of the drugs and their metabolites, as well as drug‐induced acute symptoms of the 5‐HT behavioral syndrome were also assessed. Results. Two‐way analysis of variance reveals that flibanserin‐treated females attract more male sexual interest ( P = 0.020) and trigger increased grooming ( P = 0.001) between partners. In contrast, 8‐OH‐DPAT‐treated females show increased rejection of male sexual advances ( P = 0.024), a tendency for decreased male sexual interest ( P = 0.080), and increased aggression with their male pairmates ( P = 0.049). Conclusions. While 8‐OH‐DPAT‐treated female marmosets display decreased sexual receptivity and increased aggressive interactions with their male pairmates, flibanserin‐treated female marmosets demonstrate increased affiliative behavior with their male pairmates. Such pro‐affiliation attributes may underlie flibanserin's effectiveness in treating HSDD in women. Aubert Y, Gustison ML, Gardner LA, Bohl MA, Lange JR, Allers KA, Sommer B, Datson NA, and Abbott DH. Flibanserin and 8‐OH‐DPAT implicate serotonin in association between female marmoset monkey sexual behavior and changes in pair‐bond quality. J Sex Med 2012;9:694–707.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90344/1/j.1743-6109.2011.02616.x.pd
New solar twins and the metallicity and temperature scales of the Geneva Copenhagen Survey
We search for "solar twins" in the Geneva-Copenhagen Survey (GCS) using high
resolution optical spectroscopy. We initially select Sun-like stars from the
GCS by absolute magnitude, b-y colour and metallicity close to the solar
values. Our aim is to find the stars which are spectroscopically very close to
the Sun using line depth ratios and the median equivalent widths and depths of
selected lines with a range of excitation potentials. We present the ten best
stars fulfilling combined photometric and spectroscopic criteria, of which six
are new twins. We use our full sample of Sun-like stars to examine the
calibration of the metallicity and temperature scale in the GCS. Our results
give rise to the conclusion that the GCS may be offset from the solar
temperature and metallicity for sun-like stars by 100K and 0.1dex,
respectively.Comment: 14 pages, 15 figures and 7 tables. Published versio
Spectroscopic study of solar twins and analogues
Context. Many large stellar surveys have been and are still being carried
out, providing huge amounts of data, for which stellar physical parameters will
be derived. Solar twins and analogues provide a means to test the calibration
of these stellar catalogues because the Sun is the best-studied star and
provides precise fundamental parameters. Solar twins should be centred on the
solar values. Aims. This spectroscopic study of solar analogues selected from
the Geneva-Copenhagen Survey (GCS) at a resolution of 48,000 provides effective
temperatures and metallicities for these stars. We test whether our
spectroscopic parameters, as well as the previous photometric calibrations, are
properly centred on the Sun. In addition, we search for more solar twins in our
sample. Methods. The methods used in this work are based on literature methods
for solar twin searches and on methods we developed in previous work to
distinguish the metallicity-temperature degeneracies in the differential
comparison of spectra of solar analogues versus a reference solar reflection
spectrum. Results. We derive spectroscopic parameters for 148 solar analogues
(about 70 are new entries to the literature) and verify with a-posteriori
differential tests that our values are well-centred on the solar values. We use
our dataset to assess the two alternative calibrations of the GCS parameters;
our methods favour the latest revision. We show that the choice of spectral
line list or the choice of asteroid or time of observation does not affect the
results. We also identify seven solar twins in our sample, three of which are
published here for the first time. Conclusions. Our methods provide an
independent means to differentially test the calibration of stellar catalogues
around the values of a well-known benchmark star, which makes our work
interesting for calibration tests of upcoming Galactic surveys.Comment: 12 pages, 11 figures. Published versio
Solar analogues and solar twins in the HARPS archive
We present 63 solar analogues and twins for which high signal-to-noise ratio (S/N) archival data are available for the High Accuracy Radial velocity Planet Searcher (HARPS) high-resolution spectrograph at the European Southern Observatory (ESO) 3.6-m telescope. We perform a differential analysis of these stellar spectra relative to the solar spectrum, similar to previous work using ESO 2.2-m/fiber-fed extended range optical spectrograph (FEROS) data, and expand our analysis by introducing a new method to test the temperature and metallicity calibration of Sun-like stars in the Geneva-Copenhagen Survey (GCS). The HARPS data are significantly better than the FEROS data, with improvements in S/N, spectral resolution and number of lines we can analyse. We confirm the offsets to the photometric scale found in our FEROS study. We confirm three solar twins found in the FEROS data as solar twins in the HARPS data, as well as identify six new twins.</p
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