4,297 research outputs found
Suitability of borago officinalis for minimal processing as fresh-cut produce
Borage (Borago offcinalis L.) is a wild vegetable appreciated as a folk medicine and for culinary preparations. The introduction of borage as a specialized cultivation would allow for the diversification of vegetable crops and would widen the offerings of raw and minimally processed leafy vegetables. Thus, the aim of the research was to evaluate the quality and shelf-life of fresh-cut borage stored at different temperatures. Borage plants were grown during the autumn-winter season and immediately minimally processed after harvest. Fresh-cut borage leaves packed in sealed bags were stored at 2 or 6 °C for 21 d. Weight loss, total soluble solids (TSS), titratable acidity (TA), ascorbic acid, nitrates, leaf color characteristics and overall quality were determined through the storage period. Borage plants were deemed suitable for minimal processing. Storage temperature significantly influenced the rate of quality loss. Borage leaves had an initial nitrate content of 329.3 mg kg-1 FW that was not affected by temperature or storage. TSS and TA were higher in leaves stored at 6 °C. TSS, TA and ascorbic acid content increased during storage. Minimally processed borage leaves stored at 2 °C had lower weight loss and leaf color modifications during storage and a longer shelf life than those stored at 6 °C, so were still marketable after 21 d of storage
Spatial identification of the overionized plasma in W49B
Recent Suzaku X-ray observations of the ejecta-dominated supernova remnant
W49B have shown that in the global spectrum there is a clear indication for the
presence of overionized plasma whose physical origin is still under debate. In
order to ascertain the physical origin of such a rapidly cooling plasma, we
focus on the study of its spatial localization within the X-ray emitting
ejecta. We confirm the presence of a saw-edged excess (interpreted as a strong
radiative recombination continuum) in the global spectrum above 8 keV, emerging
above the ionization-equilibrium model. We produce a hardness ratio map to
determine where the plasma is overionized and we perform a spectral analysis of
the regions with and without strong overionization. We find that the
overionized plasma is localized in the center of the remnant and in its western
jet, while it is not detected in the bright eastern jet, where the expansion of
the ejecta is hampered by their interaction with a dense interstellar cloud.
The location of overionized plasma suggests that the inner ejecta are rapidly
cooling by expansion, unlike the outer ejecta, for which expansion is hampered
by interstellar clouds seen in H2Comment: Accepted for publication as a Letter in Astronomy and Astrophysics
Hydrodynamic modelling of ejecta shrapnel in the Vela supernova remnant
Many supernova remnants (SNRs) are characterized by a knotty ejecta
structure. The Vela SNR is an excellent example of remnant in which detached
clumps of ejecta are visible as X-ray emitting bullets that have been observed
and studied in great detail. We aim at modelling the evolution of ejecta
shrapnel in the Vela SNR, investigating the role of their initial parameters
(position and density) and addressing the effects of thermal conduction and
radiative losses. We performed a set of 2-D hydrodynamic simulations describing
the evolution of a density inhomogeneity in the ejecta profile. We explored
different initial setups. We found that the final position of the shrapnel is
very sensitive to its initial position within the ejecta, while the dependence
on the initial density contrast is weaker. Our model also shows that moderately
overdense knots can reproduce the detached features observed in the Vela SNR.
Efficient thermal conduction produces detectable effects by determining an
efficient mixing of the ejecta knot with the surrounding medium and shaping a
characteristic elongated morphology in the clump.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical
Societ
Linking gamma-ray spectra of supernova remnants to the cosmic ray injection properties in the aftermath of supernovae
The acceleration times of the highest-energy particles which emit gamma-rays
in young and middle-age SNRs are comparable with SNR age. If the number of
particles starting acceleration was varying during early times after the
supernova explosion then this variation should be reflected in the shape of the
gamma-ray spectrum. We use the solution of the non-stationary equation for
particle acceleration in order to analyze this effect. As a test case, we apply
our method to describe gamma-rays from IC443. As a proxy of the IC443 parent
supernova we consider SN1987A. First, we infer the time dependence of injection
efficiency from evolution of the radio spectral index in SN1987A. Then, we use
the inferred injection behavior to fit the gamma-ray spectrum of IC443. We show
that the break in the proton spectrum needed to explain the gamma-ray emission
is a natural consequence of the early variation of the cosmic ray injection,
and that the very-high energy gamma-rays originate from particles which began
acceleration during the first months after the supernova explosion. We conclude
that the shape of the gamma-ray spectrum observed today in SNRs critically
depends on the time variation of the cosmic ray injection process in the
immediate post explosion phases. With the same model, we estimate also the
possibility in the future to detect gamma-rays from SN 1987A.Comment: A&A, accepte
The Italian version of the Thinking About Life Experiences Questionnaire and its relationship with gender, age, and life events on Facebook
The present study provided a cross-cultural validation of the Thinking About Life Experiences Scale-revised (TALE-R) in an Italian sample of Facebook users (n = 492; female = 378; male = 114; mean age 26.1) to test for replication and universality of the TALE-R three-factor model. Furthermore, it explored the interrelations among gender, age, the scores at the TALE-R and the frequency of posting textual/visual information about individuals' life events on Facebook. Results at exploratory and confirmatory factor analysis gave empirical support to both of a tripartite model for the functions of autobiographical memory (i.e., directive-behavior, social-bonding, and self-continuity) and measurement invariance of this three-factor model across gender and age. Further results at linear correlation and regression analyses showed that directive-behavior and self-continuity functions of autobiographical memory are significantly related to the ways people use Facebook for personal documentation. Age differences more than gender influence this association. Discussion and conclusion reported both theoretical and empirical implications of the findings of the study
Supernova 1987A: a Template to Link Supernovae to their Remnants
The emission of supernova remnants reflects the properties of both the
progenitor supernovae and the surrounding environment. The complex morphology
of the remnants, however, hampers the disentanglement of the two contributions.
Here we aim at identifying the imprint of SN 1987A on the X-ray emission of its
remnant and at constraining the structure of the environment surrounding the
supernova. We performed high-resolution hydrodynamic simulations describing SN
1987A soon after the core-collapse and the following three-dimensional
expansion of its remnant between days 1 and 15000 after the supernova. We
demonstrated that the physical model reproducing the main observables of SN
1987A during the first 250 days of evolution reproduces also the X-ray emission
of the subsequent expanding remnant, thus bridging the gap between supernovae
and supernova remnants. By comparing model results with observations, we
constrained the explosion energy in the range ~erg and
the envelope mass in the range . We found that the shape of
X-ray lightcurves and spectra at early epochs (<15 years) reflects the
structure of outer ejecta: our model reproduces the observations if the
outermost ejecta have a post-explosion radial profile of density approximated
by a power law with index . At later epochs, the shapes of X-ray
lightcurves and spectra reflect the density structure of the nebula around SN
1987A. This enabled us to ascertain the origin of the multi-thermal X-ray
emission, to disentangle the imprint of the supernova on the remnant emission
from the effects of the remnant interaction with the environment, and to
constrain the pre-supernova structure of the nebula.Comment: 16 pages, 11 Figures; accepted for publication on Ap
Modeling SNR Cassiopeia A from the Supernova Explosion to its Current Age: The role of post-explosion anisotropies of ejecta
The remnants of core-collapse supernovae (SNe) have complex morphologies that
may reflect asymmetries and structures developed during the progenitor SN
explosion. Here we investigate how the morphology of the SNR Cassiopeia A (Cas
A) reflects the characteristics of the progenitor SN with the aim to derive the
energies and masses of the post-explosion anisotropies responsible for the
observed spatial distribution of Fe and Si/S. We model the evolution of Cas A
from the immediate aftermath of the progenitor SN to the three-dimensional
interaction of the remnant with the surrounding medium. The post-explosion
structure of the ejecta is described by small-scale clumping of material and
larger-scale anisotropies. The hydrodynamic multi-species simulations consider
an appropriate post-explosion isotopic composition of the ejecta. The observed
average expansion rate and shock velocities can be well reproduced by models
with ejecta mass and explosion energy erg. The post-explosion anisotropies (pistons)
reproduce the observed distributions of Fe and Si/S if they had a total mass of
and a total kinetic energy of erg. The pistons produce a spatial inversion of ejecta layers at the
epoch of Cas A, leading to the Si/S-rich ejecta physically interior to the
Fe-rich ejecta. The pistons are also responsible for the development of bright
rings of Si/S-rich material which form at the intersection between the reverse
shock and the material accumulated around the pistons during their propagation.
Our result supports the idea that the bulk of asymmetries observed in Cas A are
intrinsic to the explosion.Comment: 19 pages, 14 Figures; accepted for publication on Ap
Repair Expenses, Selling Contracts, and House Prices
This paper examines the impact of repair expenses on the selling price of a house. Using data from settlement statements, we investigate the frequency and extent to which performance of major repairs is part of the sales contract. We find that most homes are restored to a "normally maintained" state each time the home changes hands, and that the cost of bringing the home to this condition is included as part of house selling price. This implies it may be unnecessary to measure maintenance levels when using transaction data to study components of house price or to construct house price indexes.
Restructuring Agency Relationships in the Real Estate Brokerage Industry: An Economic Analysis
Recent state legislative reforms of real estate agency relationships suggest that traditional agency law and practice are not meeting the needs of the parties involved in a residential real estate purchase and sales transaction. In this article, we argue that this is due, at least in part, to the bundling of information and representation services provided by brokers. This bundling results in a tradeoff between the benefits of buyers and sellers in sharing information prior to a match, and the cost to the parties individually of revealing information during bargaining. We conclude that, from an economic perspective, effective agency reform must solve this basic conflict, perhaps by unbundling the matching and representation functions.
Designing a sustainable university recharge area for electric vehicles: Technical and economic analysis
This article addresses the technical and economic challenges regarding the design of a "green" recharge area for electric vehicles at the University of Palermo in order to reduce costs and pollution connected to the charging process. Based on the behaviour of the student population, the electrical load is identified and two possible solutions are evaluated to manage the peak load: an orientation of the panels increasing the power at defined time and the use of a storage system. The main strength and weakness points of two systems are investigated by taking into account the Levelized Cost of Energy (LCOE), which reaches 75.3 \u20ac/MWh for the orientation of panel and 103 \u20ac/MWh for the storage system. Furthermore, the cost of the topologies of power plant and the cost of energy are discussed in depth
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