599 research outputs found
Visitors' expenditure behaviour at cultural events: The case of Christmas markets.
This paper examines the determinants of visitors' expenditure behaviour at cultural events. The authors analyse visitors' expenditure at the micro-level, dividing it into expenditure on accommodation and expenditure on food and beverages. The explicative variables taken into account are socio-demographic, economic, psychological and trip-related attributes. An ad hoc survey was conducted on the three most famous Christmas markets in the north of Italy in December 2008 and 2009. To achieve their aims, the authors use the robust double-hurdle model. The results indicate that travel purpose, region of origin, perception of the event, length of stay and age are significant factors influencing both the propensity to spend and the amount of money actually spent during visits. The findings will provide destination managers and tourism businesses with practical knowledge useful for destination marketing, event development and customer service
Higher depletion of lithium in planet host stars: no age and mass effect
Recent observational work by Israelian et al. has shown that sun-like planet
host stars in the temperature range 5700K < Teff < 5850K have lithium
abundances that are significantly lower than those observed for "single" field
stars. In this letter we use stellar evolutionary models to show that
differences in stellar mass and age are not responsible for the observed
correlation. This result, along with the finding of Israelian et al., strongly
suggest that the observed lithium difference is likely linked to some process
related to the formation and evolution of planetary systems.Comment: 4 pages, 4 figures, letter accepted for publication in Astronomy &
Astrophysic
The Epoch of Giant Planet Migration Planet Search Program. I. Near-Infrared Radial Velocity Jitter of Young Sun-like Stars
We present early results from the Epoch of Giant Planet Migration program, a
precise RV survey of over one hundred intermediate-age (20200 Myr) G
and K dwarfs with the Habitable-Zone Planet Finder spectrograph (HPF) at
McDonald Observatory's Hobby-Eberly Telescope (HET). The goals of this program
are to determine the timescale and dominant physical mechanism of giant planet
migration interior to the water ice line of Sun-like stars. Here, we summarize
results from the first 14 months of this program, with a focus on our custom RV
pipeline for HPF, a measurement of the intrinsic near-infrared RV activity of
young Solar analogs, and modeling the underlying population-level distribution
of stellar jitter. We demonstrate on-sky stability at the sub-2 m s
level for the K2 standard HD 3765 using a least-squares matching method to
extract precise RVs. Based on a subsample of 29 stars with at least three RV
measurements from our program, we find a median RMS level of 34 m s.
This is nearly a factor of 2 lower than the median RMS level in the optical of
60 m s for a comparison sample with similar ages and spectral types as
our targets. The observed near-infrared jitter measurements for this subsample
are well reproduced with a log-normal parent distribution with and
. Finally, by compiling RMS values from previous planet search
programs, we show that near-infrared jitter for G and K dwarfs generally decays
with age in a similar fashion to optical wavelengths, albeit with a shallower
slope and lower overall values for ages 1 Gyr
Persistent starspot signals on M dwarfs: multi-wavelength Doppler observations with the Habitable-zone Planet Finder and Keck/HIRES
Young, rapidly-rotating M dwarfs exhibit prominent starspots, which create
quasiperiodic signals in their photometric and Doppler spectroscopic
measurements. The periodic Doppler signals can mimic radial velocity (RV)
changes expected from orbiting exoplanets. Exoplanets can be distinguished from
activity-induced false positives by the chromaticity and long-term incoherence
of starspot signals, but these qualities are poorly constrained for
fully-convective M stars. Coherent photometric starspot signals on M dwarfs may
persist for hundreds of rotations, and the wavelength dependence of starspot RV
signals may not be consistent between stars due to differences in their
magnetic fields and active regions. We obtained precise multi-wavelength RVs of
four rapidly-rotating M dwarfs (AD Leo, G 227-22, GJ 1245B, GJ 3959) using the
near-infrared (NIR) Habitable-zone Planet Finder, and the optical Keck/HIRES
spectrometer. Our RVs are complemented by photometry from Kepler, TESS, and the
Las Cumbres Observatory (LCO) network of telescopes. We found that all four
stars exhibit large spot-induced Doppler signals at their rotation periods, and
investigated the longevity and optical-to-NIR chromaticity for these signals.
The phase curves remain coherent much longer than is typical for Sunlike stars.
Their chromaticity varies, and one star (GJ 3959) exhibits optical and NIR RV
modulation consistent in both phase and amplitude. In general, though, we find
that the NIR amplitudes are lower than their optical counterparts. We conclude
that starspot modulation for rapidly-rotating M stars frequently remains
coherent for hundreds of stellar rotations, and gives rise to Doppler signals
that, due to this coherence, may be mistaken for exoplanets.Comment: Accepted for publication in the Astrophysical Journa
Soil biochemistry and microbial activity in vineyards under conventional and organic management at Northeast Brazil.
The SĂŁo Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that orgThe SĂŁo Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that organic fertilization can improve soil quality, we compared the effects of conventional and organic soil management on microbial activity and mycorrhization of seedless grape crops. We measured glomerospores number, most probable number (MPN) of propagules, richness of arbuscular mycorrhizal fungi (AMF) species, AMF root colonization, EE-BRSP production, carbon microbial biomass (C-MB), microbial respiration, fluorescein diacetate hydrolytic activity (FDA) and metabolic coefficient (qCO2). The organic management led to an increase in all variables with the exception of EE-BRSP and qCO2. Mycorrhizal colonization increased from 4.7% in conventional crops to 15.9% in organic crops. Spore number ranged from 4.1 to 12.4 per 50 g-1 soil in both management systems. The most probable number of AMF propagules increased from 79 cm-3 soil in the conventional system to 110 cm-3 soil in the organic system. Microbial carbon, CO2 emission, and FDA activity were increased by 100 to 200% in the organic crop. Thirteen species of AMF were identified, the majority in the organic cultivation system. Acaulospora excavata, Entrophospora infrequens, Glomus sp.3 and Scutellospora sp. were found only in the organically managed crop. S. gregaria was found only in the conventional crop. Organically managed vineyards increased mycorrhization and general soil microbial activity
Teachers as writers: a systematic review
This paper is a critical literature review of empirical work from 1990-2015 on teachers as writers. It interrogates the evidence on teachersâ attitudes to writing, their sense of themselves as writers and the potential impact of teacher writing on pedagogy or student outcomes in writing. The methodology was carried out in four stages. Firstly, educational databases keyword searches located 438 papers. Secondly, initial screening identified 159 for further scrutiny, 43 of which were found to specifically address teachersâ writing identities and practices. Thirdly, these sources were screened further using inclusion/exclusion criteria. Fourthly, the 22 papers judged to satisfy the criteria were subject to in-depth analysis and synthesis. The findings reveal that the evidence base in relation to teachers as writers is not strong, particularly with regard to the impact of teachersâ writing on student outcomes. The review indicates that teachers have narrow conceptions of what counts as writing and being a writer and that multiple tensions exist, relating to low self-confidence, negative writing histories, and the challenge of composing and enacting teacher and writer positions in school. However, initial training and professional development programmes do appear to afford opportunities for reformulation of attitudes and sense of self as writer
Easing into the Academy: Using Technology to Foster Cross-Institutional Critical Friendships
This article addresses the ways in which early career teacher educators can support each other as they enter the academic community. By utilizing technology as an instrument to engage in a cross-country critical friendship, the authors were able to engage in a dialogue that grew out of mutual interests and concerns. Through critical reflection, they were able to address the question: How can we, two early-career teacher educators, push ourselves and one another to more critically examine our teaching practices? In doing so, each ânew educatorâ grew more confident in claiming one\u27s voice as a sustainable critical friendship emerged
Gender and sexual orientation differences in cognition across adulthood : age is kinder to women than to men regardless of sexual orientation
Despite some evidence of greater age-related deterioration of the brain in males than in females, gender differences in rates of cognitive aging have proved inconsistent. The present study employed web-based methodology to collect data from people aged 20-65 years (109,612 men; 88,509 women). As expected, men outperformed women on tests of mental rotation and line angle judgment, whereas women outperformed men on tests of category fluency and object location memory. Performance on all tests declined with age but significantly more so for men than for women. Heterosexuals of each gender generally outperformed bisexuals and homosexuals on tests where that gender was superior; however, there were no clear interactions between age and sexual orientation for either gender. At least for these particular tests from young adulthood to retirement, age is kinder to women than to men, but treats heterosexuals, bisexuals, and homosexuals just the same
TOI-5375 B: A Very Low Mass Star at the Hydrogen-Burning Limit Orbiting an Early M-type Star
The TESS mission detected a companion orbiting TIC 71268730, categorized it
as a planet candidate, and designated the system TOI-5375. Our follow-up
analysis using radial velocity data from the Habitable-zone Planet Finder
(HPF), photometric data from Red Buttes Observatory (RBO), and speckle imaging
with NN-EXPLORE Exoplanet Stellar Speckle Imager (NESSI) determined that the
companion is a very low mass star (VLMS) near the hydrogen-burning mass limit
with a mass of 0.080\pm{0.002} M_{\Sun} (), a radius of
0.1114^{+0.0048}_{-0.0050} R_{\Sun} (1.0841), and
brightness temperature of K. This object orbits with a period of
1.721553 days around an early M dwarf star
(0.62\pm{0.016}M_{\Sun}). TESS photometry shows regular variations in the
host star's TESS light curve, which we interpreted as activity-induced
variation of 2\%, and used this variability to measure the host star's
stellar rotation period of 1.9716 days. The TOI-5375
system provides tight constraints on stellar models of low-mass stars at the
hydrogen-burning limit and adds to the population in this important region.Comment: 15 pages, 8 figures, Accepted to the Astronomical Journa
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