976 research outputs found
The Effect of Diffuse Light on Crops
Light is not evenly distributed in Dutch glass greenhouses, but this can be improved with diffuse light. Modern greenhouse coverings are able to transform most of the light entering the greenhouse into diffuse light. Wageningen UR Greenhouse Horticulture has studied the effect of diffuse light on crops for several years. Modelling and experimental studies showed that crops such as fruit vegetables with a high plant canopy as well as ornamentals with a small plant canopy can utilize diffuse light better than direct light. Diffuse light penetrates the middle layers of a high-grown crop and results in a better horizontal light distribution in the greenhouse. Diffuse light is absorbed to a better degree by the middle leaf layers of cucumber, resulting in a higher photosynthesis. The actual photosynthesis of four pot plant species was found to be increased and crop temperatures were lower during high irradiation. The yield of cucumbers was increased, and the growth rate of several potted plants was increased. These investigations have resulted in a quantitative foundation for the potentials of diffuse light in Dutch horticultural greenhouses and the selection and verification of technological methods to convert direct sunlight into diffuse light
Detection of the strongest magnetic field in a sunspot light bridge
Traditionally, the strongest magnetic fields on the Sun have been measured in
sunspot umbrae. More recently, however, much stronger fields have been measured
at the ends of penumbral filaments carrying the Evershed and counter-Evershed
flows. Superstrong fields have also been reported within a light bridge
separating two umbrae of opposite polarities. We aim to accurately determine
the strengths of the strongest fields in a light bridge using an advanced
inversion technique and to investigate their detailed structure. We analyze
observations from the spectropolarimeter on board the Hinode spacecraft of the
active region AR 11967. The thermodynamic and magnetic configurations are
obtained by inverting the Stokes profiles using an inversion scheme that allows
multiple height nodes. Both the traditional 1D inversion technique and the
so-called 2D coupled inversions, which take into account the point spread
function of the Hinode telescope, are used. We find a compact structure with an
area of 32.7 arcsec within a bipolar light bridge with field strengths
exceeding 5 kG, confirming the strong fields in this light bridge reported in
the literature. Two regions associated with downflows of 5 km s
harbor field strengths larger than 6.5 kG, covering a total area of 2.97
arcsec. The maximum field strength found is 8.2 kG, which is the largest
ever observed field in a bipolar light bridge up to now.Comment: ApJ 2020, 895:12
Stokes imaging polarimetry using image restoration: A calibration strategy for Fabry-P\'{e}rot based instruments
context: The combination of image restoration and a Fabry-P\'{e}rot
interferometer (FPI) based instrument in solar observations results in specific
calibration issues. FPIs generally show variations over the field-of-view,
while in the image restoration process, the 1-to-1 relation between pixel space
and image space is lost, thus complicating any correcting for such variations.
aims: We develop a data reduction method that takes these issues into account
and minimizes the resulting errors. methods: By accounting for the time
variations in the telescope's Mueller matrix and using separate calibration
data optimized for the wavefront sensing in the MOMFBD image restoration
process and for the final deconvolution of the data, we have removed most of
the calibration artifacts from the resulting data. results: Using this method
to reduce full Stokes data from CRISP at the SST, we find that it drastically
reduces the instrumental and image restoration artifacts resulting from cavity
errors, reflectivity variations, and the polarization dependence of flatfields.
The results allow for useful scientific interpretation. Inversions of restored
data from the sunspot AR11029 using the Nicole inversion code, reveal
strong (~10 km/s) downflows near the disk center side of the umbra.
conclusions: The use of image restoration in combination with an FPI-based
instrument leads to complications in the calibrations and intrinsic limitations
to the accuracy that can be achieved. We find that for CRISP, the resulting
errors can be kept mostly below the polarimetric accuracy of ~10^-3. Similar
instruments aiming for higher polarimetric and high spectroscopic accuracy,
will, however, need to take these problems into account. keywords: Techniques:
image processing, polarimetric, imaging spectroscopy, Sun: surface magnetism,
sunspots, activityComment: Astronomy and Astrophysics (accepted
Emission Lines in the Spectrum of the 3He Star 3 Cen A
Emission in the 4d - 4f transitions of MnII (multiplet 13, 6122-6132 Ang), in
the 4f - 6g transitions of PII, and in 6149.5 Ang of HgII has been detected in
the spectrum of the helium weak star 3 Centauri A (B5 III-IVp). Weaker emission
from the same MnII multiplet is also seen in the hot, mild HgMn star 46 Aquila
(B9 III).It is suggested that the emission is of photospheric origin and may be
evidence for the stratification of manganese, phosphorus and mercury in the
photosphere of 3 CenA, and of manganese in 46Aql.Comment: 16 pages, 3 figure
Accuracy of the detection of binding events using 3d single particle tracking
Biological and Soft Matter Physic
Maximum Entropy Limit of Small-scale Magnetic Field Fluctuations in the Quiet Sun
The observed magnetic field on the solar surface is characterized by a very
complex spatial and temporal behavior. Although feature-tracking algorithms
have allowed us to deepen our understanding of this behavior, subjectivity
plays an important role in the identification and tracking of such features. In
this paper, we continue studies Gorobets, A. Y., Borrero, J. M., & Berdyugina,
S. 2016, ApJL, 825, L18 of the temporal stochasticity of the magnetic field on
the solar surface without relying either on the concept of magnetic features or
on subjective assumptions about their identification and interaction. We
propose a data analysis method to quantify fluctuations of the line-of-sight
magnetic field by means of reducing the temporal field's evolution to the
regular Markov process. We build a representative model of fluctuations
converging to the unique stationary (equilibrium) distribution in the long time
limit with maximum entropy. We obtained different rates of convergence to the
equilibrium at fixed noise cutoff for two sets of data. This indicates a strong
influence of the data spatial resolution and mixing-polarity fluctuations on
the relaxation process. The analysis is applied to observations of magnetic
fields of the relatively quiet areas around an active region carried out during
the second flight of the Sunrise/IMaX and quiet Sun areas at the disk center
from the Helioseismic and Magnetic Imager on board the Solar Dynamics
Observatory satellite.Comment: 11 pages, 5 figures, The Astrophysical Journal Supplement Series
(accepted
Developmental neurobiology of cerebellar and Basal Ganglia connections
BACKGROUND: The high prevalence of mixed phenotypes of Early Onset Ataxia (EOA) with comorbid dystonia has shifted the pathogenetic concept from the cerebellum towards the interconnected cerebellar motor network. This paper on EOA with comorbid dystonia (EOA-dystonia) explores the conceptual relationship between the motor phenotype and the cortico-basal-ganglia-ponto-cerebellar network. METHODS: In EOA-dystonia, we reviewed anatomic-, genetic- and biochemical-studies on the comorbidity between ataxia and dystonia. RESULTS: In a clinical EOA cohort, the prevalence of dystonia was over 60%. Both human and animal studies converge on the underlying role for the cortico-basal-ganglia-ponto-cerebellar network. Genetic -clinical and -in silico network studies reveal underlying biological pathways for energy production and neural signal transduction. CONCLUSIONS: EOA-dystonia phenotypes are attributable to the cortico-basal-ganglia-ponto-cerebellar network, instead of to the cerebellum, alone. The underlying anatomic and pathogenetic pathways have clinical implications for our understanding of the heterogeneous phenotype, neuro-metabolic and genetic testing and potentially also for new treatment strategies, including neuro-modulation
Trust not in money: The effect of financial conflict of interest disclosure on dietary behavioural intention
Purpose
To determine the impact of financial conflict of interest (FCI) disclosure on dietary behavioural intention related to the glycaemic index (GI) of food.
Design/methodology/approach
Seventy-two participants were randomly allocated to two conditions by reading an academic journal article about GI that contained an FCI disclosure (conflict) or a statement detailing that the authors had no FCI to declare (no-conflict). Using a questionnaire, participants made judgments about the article and authors as well as intention to perform GI-related behaviour. These were then analysed for significant differences between the two conditions.
Findings
Although no significant differences emerged between group means of judgments about the article, those in the conflict condition judged the authors as significantly less trustworthy and credible than those in the conflict condition. Contrary to expectation, those in the conflict condition reported significantly higher intentions to perform GI-related behaviour.
Research limitations/implications
The present research must be conducted in other populations of interest in order to establish if the results can be generalised.
Practical implications
The results suggest that FCI disclosure might be best placed at the beginning of articles and that education about FCI be made available to the general public.
Originality/value
This paper examines the practical implications of FCI disclosure. It also focuses on a readership beyond an academic community who is well-acquainted with the subject area and issues pertaining to FCI
Kinematics of Magnetic Bright Features in the Solar Photosphere
Convective flows are known as the prime means of transporting magnetic fields
on the solar surface. Thus, small magnetic structures are good tracers of the
turbulent flows. We study the migration and dispersal of magnetic bright
features (MBFs) in intergranular areas observed at high spatial resolution with
Sunrise/IMaX. We describe the flux dispersal of individual MBFs as a diffusion
process whose parameters are computed for various areas in the quiet Sun and
the vicinity of active regions from seeing-free data. We find that magnetic
concentrations are best described as random walkers close to network areas
(diffusion index, gamma=1.0), travelers with constant speeds over a
supergranule (gamma=1.9-2.0), and decelerating movers in the vicinity of flux
emergence and/or within active regions (gamma=1.4-1.5). The three types of
regions host MBFs with mean diffusion coefficients of 130 km^2/s, 80-90 km^2/s,
and 25-70 km^2/s, respectively. The MBFs in these three types of regions are
found to display a distinct kinematic behavior at a confidence level in excess
of 95%.Comment: 8 pages, 4 figure
Solar Coronal Loops Associated with Small-scale Mixed Polarity Surface Magnetic Fields
How and where are coronal loops rooted in the solar lower atmosphere? The
details of the magnetic environment and its evolution at the footpoints of
coronal loops are crucial to understanding the processes of mass and energy
supply to the solar corona. To address the above question, we use
high-resolution line-of-sight magnetic field data from the Imaging Magnetograph
eXperiment instrument on the SUNRISE balloon-borne observatory and coronal
observations from the Atmospheric Imaging Assembly onboard the Solar Dynamics
Observatory of an emerging active region. We find that the coronal loops are
often rooted at the locations with minor small-scale but persistent
opposite-polarity magnetic elements very close to the larger dominant polarity.
These opposite-polarity small-scale elements continually interact with the
dominant polarity underlying the coronal loop through flux cancellation. At
these locations we detect small inverse Y-shaped jets in chromospheric Ca II H
images obtained from the SUNRISE Filter Imager during the flux cancellation.
Our results indicate that magnetic flux cancellation and reconnection at the
base of coronal loops due to mixed polarity fields might be a crucial feature
for the supply of mass and energy into the corona.Comment: Published in the Astrophysical Journal Supplement Serie
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