439 research outputs found
Einfluß unterschiedlicher Anbauarten – mineralisch, organisch, biologisch-dynamisch – auf Kartoffeln: Inhaltsstoffe, Sensorik, Festigkeitskennwerte und bildschaffende Methoden
Grundsätzlich sprachen die Kartoffeln der Sorte ´Granola´ sehr schwach auf die eingesetzten Versuchsfaktoren an, sodaß die Unterschiede selten statistisch abgesichert werden konnten.
Bei denjenigen Inhaltsstoffen, die deutlicher auf den Anbaufaktor Düngermenge ansprachen, reagierten die Knollen der mineralisch gedüngten Varianten eindeutig stärker (Abnahme der Trockenmasse, der Saccharose-, Stärke- und Clorid-Gehalte, Zunahme der Glukose-, Fruktose-, Fluorid- und Asche-Gehalte) als die Vergleichsvarianten. Ein Grund hierfür könnte die schnellere Verfügbarkeit des mineralischen Düngers gewesen sein.
Die biologisch-dynamisch gedüngten Knollen zeigten nur bei drei Parametern dieselbe Reaktion auf die Intensivierung der Düngung wie die organisch gedüngten auf (Zunahme der Chlorid- und Asche-Gehalte, gleichbleibende Fluorid-Gehalte). Bei vier Merkmalen reagierten die biologisch-dynamischen Knollen überhaupt nicht oder sehr gering, wogegen die organisch gedüngten Kartoffeln eine Abnahme im Trockenmasse- und Saccharosegehalt bzw. keine gerichteten Tendenzen in den Glukose- und Fruktosegehalten aufwiesen.
Die Festigkeitskennwerte der mineralisch gedüngten Kartoffeln wurde, im Vergleich zu den beiden anderen Varianten, schwächer bewertet. Die sensorischen Untersuchungen ergaben keine Bevorzugung einzelner Varianten, jedoch, besonders bei der minera-lischen Variante, eine tendenzielle Abnahme der sensorischen Qualität mit zunehmender Düngung. Die Ergebnisse der Untersuchungen zur „Vitalqualität“ mit Hilfe bildschaf-fender Methoden bestätigte die prinzipielle Eignung dieser Methode für ergänzende Qualitätsuntersuchungen.
Eine abschließende Beurteilung der Qualität der unterschiedlichen Anbauvarianten wird erst in Verbindung der bisherigen Daten mit noch zur Analyse anstehenden Parametern (Nitrat, Aminosäuren, Ascorbinsäure, Kalium) möglich sein. Des weiteren wird in laufenden Sortenversuchen geprüft, ob andere Sorten stärker auf die verschiedenen Versuchsfaktoren reagieren
Quality Comparison of Mineral, Organic and Biodynamic Cultivation of Potatoes: Contents, Strength Criteria, Sensory Investigations and Picture-Creating Methods
Nutritional quality of food can be characterized by the content of beneficial and harmful substances. For today’s consumers the most important criteria for buying potatoes are taste, quality and shelf-life.
Biodynamic preparations are used by about 20% of all organic farms in Germany. These preparations do not primarily serve to increase the yield but are said to support the production of high quality food, having balanced nutrient contents and improved shelf-life characteristics.
Since 1993 investigations have been carried out to evaluate the effect of mineral fertilization and organic manuring at varied intensities, combined with application of biodynamic preparations, on some of these parameters.
The potatoes of the variety ´Granola´ responded rather slightly to the factors of the trial, hence statistical differences could be confirmed only in few cases. Tubers deriving from the mineral fertilized plots showed the strongest response to elevated fertilization (decrease in dry matter, sucrose, chloride content and density, and an increase in glucose, fructose, fluoride and ash content). Only in three parameters tubers from the biodynamic plots responded in the same way as the organic ones to elevated fertilization (increase in the chloride and ash contents, stagnating fluoride contents). In four parameters, no or only a weak response of the biodynamic tubers has been found, whereas organic potatoes showed decreasing dry matter and sucrose contents, but no distinctive tendency in the parameters glucose and fructose. The parameter strength criteria has been assessed as the weakest in mineral fertilized potatoes. The sensory investigations did not allow to differentiate between the three cropping systems but there was a tendency of worsening sensoric quality at increased fertilization, particularly in the tubers of the mineral plots. The results of the determination of vital quality following picture-creating methods confirmed the applicability of this assay for additional quality determinations.
A final assessment of the quality according to the different cropping systems cannot be made at this point of time. Therefore, further parameters (nitrate, potassium, amino acids, ascorbic acid) will be analyzed which might allow a final assessment in combination with the present data. Furthermore, current trials might reveal if other varieties respond stronger to the relevant factors
Prospect of Studying Hard X- and Gamma-Rays from Type Ia Supernovae
We perform multi-dimensional, time-dependent radiation transfer simulations
for hard X-ray and gamma-ray emissions, following radioactive decays of 56Ni
and 56Co, for two-dimensional delayed detonation models of Type Ia supernovae
(SNe Ia). The synthetic spectra and light curves are compared with the
sensitivities of current and future observatories for an exposure time of 10^6
seconds. The non-detection of the gamma-ray signal from SN 2011fe at 6.4 Mpc by
SPI on board INTEGRAL places an upper limit for the mass of 56Ni of \lesssim
1.0 Msun, independently from observations in any other wavelengths. Signals
from the newly formed radioactive species have not been convincingly measured
yet from any SN Ia, but the future X-ray and gamma-ray missions are expected to
deepen the observable horizon to provide the high energy emission data for a
significant SN Ia sample. We predict that the hard X-ray detectors on board
NuStar (launched in 2012) or ASTRO-H (scheduled for launch in 2014) will reach
to SNe Ia at \sim15 Mpc, i.e., one SN every few years. Furthermore, according
to the present results, the soft gamma-ray detector on board ASTRO-H will be
able to detect the 158 keV line emission up to \sim25 Mpc, i.e., a few SNe Ia
per year. Proposed next generation gamma-ray missions, e.g., GRIPS, could reach
to SNe Ia at \sim20 - 35 Mpc by MeV observations. Those would provide new
diagnostics and strong constraints on explosion models, detecting rather
directly the main energy source of supernova light.Comment: 14 pages, 7 figures, 1 table, accepted for publication in Ap
Sub-luminous type Ia supernovae from the mergers of equal-mass white dwarfs with M~0.9 M_sun
Type Ia supernovae (SNe Ia) are thought to result from thermonuclear
explosions of carbon-oxygen white dwarf stars. Existing models generally
explain the observed properties, with the exception of the sub-luminous
1991-bg-like supernovae. It has long been suspected that the merger of two
white dwarfs could give rise to a type Ia event, but hitherto simulations have
failed to produce an explosion. Here we report a simulation of the merger of
two equal-mass white dwarfs that leads to an underluminous explosion, though at
the expense of requiring a single common-envelope phase, and component masses
of ~0.9 M_sun. The light curve is too broad, but the synthesized spectra, red
colour and low expansion velocities are all close to what is observed for
sub-luminous 1991bg-like events. While mass ratios can be slightly less than
one and still produce an underluminous event, the masses have to be in the
range 0.83-0.9 M_sun.Comment: Accepted to Natur
Theory of "ferrisuperconductivity" in
We construct a two component Ginzburg-Landau theory with coherent pair motion
and incoherent quasiparticles for the phase diagram of .
The two staggered superconducting states live at the Brillouin zone center and
the zone boundary, and coexist for temperatures at concentrations
. We predict below
appearance of a charge density wave (CDW) and Be-sublattice distortion. The
distortion explains the SR relaxation anomaly, and Th-impurity mediated
scattering of ultrasound to CDW fluctuations explains the attenuation peak.Comment: 4 pages, 4 eps figures, REVTe
Extensive HST Ultraviolet Spectra and Multi-wavelength Observations of SN 2014J in M82 Indicate Reddening and Circumstellar Scattering by Typical Dust
SN 2014J in M82 is the closest detected Type Ia supernova (SN Ia) in at least
28 years and perhaps in 410 years. Despite its small distance of 3.3 Mpc, SN
2014J is surprisingly faint, peaking at V = 10.6 mag, and assuming a typical SN
Ia luminosity, we infer an observed visual extinction of A_V = 2.0 +/- 0.1 mag.
But this picture, with R_V = 1.6 +/- 0.2, is too simple to account for all
observations. We combine 10 epochs (spanning a month) of HST/STIS ultraviolet
through near-infrared spectroscopy with HST/WFC3, KAIT, and FanCam photometry
from the optical to the infrared and 9 epochs of high-resolution TRES
spectroscopy to investigate the sources of extinction and reddening for SN
2014J. We argue that the wide range of observed properties for SN 2014J is
caused by a combination of dust reddening, likely originating in the
interstellar medium of M82, and scattering off circumstellar material. For this
model, roughly half of the extinction is caused by reddening from typical dust
(E(B-V ) = 0.45 mag and R_V = 2.6) and roughly half by scattering off LMC-like
dust in the circumstellar environment of SN 2014J.Comment: 17 pages (excluding references and tables), 15 figures, accepted to
MNRAS. A high-resolution HST image of SN 2014J in M82 is available upon
reques
Constraining Type Ia supernova models: SN 2011fe as a test case
The nearby supernova SN 2011fe can be observed in unprecedented detail.
Therefore, it is an important test case for Type Ia supernova (SN Ia) models,
which may bring us closer to understanding the physical nature of these
objects. Here, we explore how available and expected future observations of SN
2011fe can be used to constrain SN Ia explosion scenarios. We base our
discussion on three-dimensional simulations of a delayed detonation in a
Chandrasekhar-mass white dwarf and of a violent merger of two white
dwarfs-realizations of explosion models appropriate for two of the most
widely-discussed progenitor channels that may give rise to SNe Ia. Although
both models have their shortcomings in reproducing details of the early and
near-maximum spectra of SN 2011fe obtained by the Nearby Supernova Factory
(SNfactory), the overall match with the observations is reasonable. The level
of agreement is slightly better for the merger, in particular around maximum,
but a clear preference for one model over the other is still not justified.
Observations at late epochs, however, hold promise for discriminating the
explosion scenarios in a straightforward way, as a nucleosynthesis effect leads
to differences in the 55Co production. SN 2011fe is close enough to be followed
sufficiently long to study this effect.Comment: Accepted for publication in The Astrophysical Journal Letter
500 Days of SN 2013dy: spectra and photometry from the ultraviolet to the infrared
SN 2013dy is a Type Ia supernova for which we have compiled an extraordinary
dataset spanning from 0.1 to ~ 500 days after explosion. We present 10 epochs
of ultraviolet (UV) through near-infrared (NIR) spectra with HST/STIS, 47
epochs of optical spectra (15 of them having high resolution), and more than
500 photometric observations in the BVrRiIZYJH bands. SN 2013dy has a broad and
slowly declining light curve (delta m(B) = 0.92 mag), shallow Si II 6355
absorption, and a low velocity gradient. We detect strong C II in our earliest
spectra, probing unburned progenitor material in the outermost layers of the SN
ejecta, but this feature fades within a few days. The UV continuum of SN
2013dy, which is strongly affected by the metal abundance of the progenitor
star, suggests that SN 2013dy had a relatively high-metallicity progenitor.
Examining one of the largest single set of high-resolution spectra for a SN Ia,
we find no evidence of variable absorption from circumstellar material.
Combining our UV spectra, NIR photometry, and high-cadence optical photometry,
we construct a bolometric light curve, showing that SN 2013dy had a maximum
luminosity of 10.0^{+4.8}_{-3.8} * 10^{42} erg/s. We compare the synthetic
light curves and spectra of several models to SN 2013dy, finding that SN 2013dy
is in good agreement with a solar-metallicity W7 model.Comment: 22 pages, 18 figures, replaced with version accecpted for publication
in MNRA
Bonding, Moment Formation, and Magnetic Interactions in Ca14MnBi11 and Ba14MnBi11
The ``14-1-11'' phase compounds based on magnetic Mn ions and typified by
Ca14MnBi11 and Ba14MnBi11 show unusual magnetic behavior, but the large number
(104) of atoms in the primitive cell has precluded any previous full electronic
structure study. Using an efficient, local orbital based method within the
local spin density approximation to study the electronic structure, we find a
gap between a bonding valence band complex and an antibonding conduction band
continuum. The bonding bands lack one electron per formula unit of being
filled, making them low carrier density p-type metals. The hole resides in the
MnBi4 tetrahedral unit and partially compensates the high spin d^5 Mn moment,
leaving a net spin near 4 \mu_B that is consistent with experiment. These
manganites are composed of two disjoint but interpenetrating `jungle gym'
networks of spin 4/2 MnBi4^{9-} units with ferromagnetic interactions within
the same network, and weaker couplings between the networks whose sign and
magnitude is sensitive to materials parameters. Ca14MnBi11 is calculated to be
ferromagnetic as observed, while for Ba14MnBi11 (which is antiferromagnetic)
the ferro- and antiferromagnetic states are calculated to be essentially
degenerate. The band structure of the ferromagnetic states is very close to
half metallic.Comment: 17 pages, containing 10 postscript figures and 5 tables. Two
additional figures (Fig.8 and 11 of the paper) are provided in JPG format in
separate files. Submitted to Phys. Rev. B on September 20th 200
Regulation of Thromboxane Receptor Signaling at Multiple Levels by Oxidative Stress-Induced Stabilization, Relocation and Enhanced Responsiveness
Thromboxane A(2) (TxA(2)) is a major, unstable arachidonic acid metabolite, and plays a key role in normal physiology and control of vascular tone. The human thromboxane receptor (TPβ), expressed in COS-7 cells, is located predominantly in the endoplasmic reticulum (ER). Brief hydrogen peroxide exposure increases the efficiency of translocation of TPβ from the ER into the Golgi complex, inducing maturation and stabilization of TPβ. However, the ultimate fate of this post-ER TPβ pool is not known, nor is its capacity to initiate signal transduction. Here we specifically assessed if functional TPβ was transported to the plasma membrane following H(2)O(2) exposure.We demonstrate, by biotinylation and confocal microscopy, that exposure to H(2)O(2) results in rapid delivery of a cohort of TPβ to the cell surface, which is stable for at least eight hours. Surface delivery is brefeldin A-sensitive, indicating that translocation of this receptor cohort is from internal pools and via the Golgi complex. H(2)O(2) treatment results in potentiation of the increase to intracellular calcium concentrations in response to TPβ agonists U46619 and 8-iso PGF(2α) and also in the loss of ligand-dependent receptor internalization. Further there is increased responsiveness to a second application of the agonist. Finally we demonstrate that the effect of H(2)O(2) on stimulating surface delivery is shared with the FP prostanoid receptor but not the EP3 or EP4 receptors.In summary, brief exposure to H(2)O(2) results in an immediate and sustained increase in the surface pool of thromboxane receptor that is capable of mediating a persistent hyper-responsiveness of the cell and suggests a highly sophisticated mechanism for rapidly regulating thromboxane signaling
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