223 research outputs found
Nachhaltigkeit von drei graslandbasierten Milchproduktionssystemen in der Schweiz mit der Bewertungsmethode RISE
Dairy farming is a key sector for Swiss agriculture and the food industry. Therefore, sustainability of dairy farms is important. Grassland-based farming systems are the
most common production system, combining the indoor feeding of fresh grass with partial grazing. The effects of three dairy production systems (VW: full grazing plus on
avg. 46±93 SD kg concentrate (KF), GFKF: indoor feeding/partial grazing plus on avg. 345±204 SD kg KF and GFKFplus: indoor feeding/partial grazing plus on avg.
1007±353 SD kg KF) on sustainability, according to RISE, were studied on 12 pilot farms in the lowland of Switzerland. In most of the sustainability themes, the farms
performed medium to good according to the RISE evaluation scale. The GFKFplus farms produced the highest output of milk by low N- and P-self-sufficiency, showed the
highest energy input and the lowest greenhouse gas output per kg milk. The GFKF group achieved remarkable results by moderate N-, P- and energy inputs. The VW farms showed a lower milk output but a higher level of feed self-sufficiency and a lower energy consumption. In the search for the optimal production strategy, farms should consider the individual farm structure (contiguous areas), the market potential but also social aspects such as the preferences of the farmer`s family
Co-phasing the Large Binocular Telescope: status and performance of LBTI/PHASECam
The Large Binocular Telescope Interferometer is a NASA-funded nulling and
imaging instrument designed to coherently combine the two 8.4-m primary mirrors
of the LBT for high-sensitivity, high-contrast, and high-resolution infrared
imaging (1.5-13 um). PHASECam is LBTI's near-infrared camera used to measure
tip-tilt and phase variations between the two AO-corrected apertures and
provide high-angular resolution observations. We report on the status of the
system and describe its on-sky performance measured during the first semester
of 2014. With a spatial resolution equivalent to that of a 22.8-meter telescope
and the light-gathering power of single 11.8-meter mirror, the co-phased LBT
can be considered to be a forerunner of the next-generation extremely large
telescopes (ELT).Comment: 8 pages, 5 figures, SPIE Conference proceeding
First-light LBT nulling interferometric observations: warm exozodiacal dust resolved within a few AU of eta Corvi
We report on the first nulling interferometric observations with the Large
Binocular Telescope Interferometer (LBTI), resolving the N' band (9.81 - 12.41
um) emission around the nearby main-sequence star eta Crv (F2V, 1-2 Gyr). The
measured source null depth amounts to 4.40% +/- 0.35% over a field-of-view of
140 mas in radius (~2.6\,AU at the distance of eta Corvi) and shows no
significant variation over 35{\deg} of sky rotation. This relatively low null
is unexpected given the total disk to star flux ratio measured by Spitzer/IRS
(~23% across the N' band), suggesting that a significant fraction of the dust
lies within the central nulled response of the LBTI (79 mas or 1.4 AU).
Modeling of the warm disk shows that it cannot resemble a scaled version of the
Solar zodiacal cloud, unless it is almost perpendicular to the outer disk
imaged by Herschel. It is more likely that the inner and outer disks are
coplanar and the warm dust is located at a distance of 0.5-1.0 AU,
significantly closer than previously predicted by models of the IRS spectrum
(~3 AU). The predicted disk sizes can be reconciled if the warm disk is not
centrosymmetric, or if the dust particles are dominated by very small grains.
Both possibilities hint that a recent collision has produced much of the dust.
Finally, we discuss the implications for the presence of dust at the distance
where the insolation is the same as Earth's (2.3 AU).Comment: 9 pages, 6 figures, accepted for publication in Ap
The HOSTS Survey for Exozodiacal Dust: Preliminary results and future prospects
[abridged] The presence of large amounts of dust in the habitable zones of
nearby stars is a significant obstacle for future exo-Earth imaging missions.
We executed an N band nulling interferometric survey to determine the typical
amount of such exozodiacal dust around a sample of nearby main sequence stars.
The majority of our data have been analyzed and we present here an update of
our ongoing work. We find seven new N band excesses in addition to the high
confidence confirmation of three that were previously known. We find the first
detections around Sun-like stars and around stars without previously known
circumstellar dust. Our overall detection rate is 23%. The inferred occurrence
rate is comparable for early type and Sun-like stars, but decreases from 71%
[+11%/-20%] for stars with previously detected mid- to far-infrared excess to
11% [+9%/-4%] for stars without such excess, confirming earlier results at high
confidence. For completed observations on individual stars, our sensitivity is
five to ten times better than previous results. Assuming a lognormal luminosity
function of the dust, we find upper limits on the median dust level around all
stars without previously known mid to far infrared excess of 11.5 zodis at 95%
confidence level. The corresponding upper limit for Sun-like stars is 16 zodis.
An LBTI vetted target list of Sun-like stars for exo-Earth imaging would have a
corresponding limit of 7.5 zodis. We provide important new insights into the
occurrence rate and typical levels of habitable zone dust around main sequence
stars. Exploiting the full range of capabilities of the LBTI provides a
critical opportunity for the detailed characterization of a sample of
exozodiacal dust disks to understand the origin, distribution, and properties
of the dust.Comment: To appear in SPIE Astronomical Telescopes + Instrumentation 2018
proceedings. Some typos fixed, one reference adde
Partial Netrin-1 Deficiency Aggravates Acute Kidney Injury
The netrin family of secreted proteins provides migrational cues in the developing central nervous system. Recently, netrins have also been shown to regulate diverse processes beyond their functions in the brain, incluing the ochrestration of inflammatory events. Particularly netrin-1 has been implicated in dampening hypoxia-induced inflammation. Here, we hypothesized an anti-inflammatory role of endogenous netrin-1 in acute kidney injury (AKI). As homozygous deletion of netrin-1 is lethal, we studied mice with partial netrin-1 deletion (Ntn-1+/− mice) as a genetic model. In fact, Ntn-1+/− mice showed attenuated Ntn-1 levels at baseline and following ischemic AKI. Functional studies of AKI induced by 30 min of renal ischemia and reperfusion revealed enhanced kidney dysfunction in Ntn-1+/− mice as assessed by measurements of glomerular filtration, urine flow rate, urine electrolytes, serum creatinine and creatinine clearance. Consistent with these findings, histological studies indicated a more severe degree kidney injury. Similarly, elevations of renal and systemic inflammatory markers were enhanced in mice with partial netrin-1 deficiency. Finally, treatment of Ntn-1+/− mice with exogenous netrin-1 restored a normal phenotype during AKI. Taking together, these studies implicate endogenous netrin-1 in attenuating renal inflammation during AKI
Co-Phasing the Large Binocular Telescope:
The Large Binocular Telescope Interferometer is a NASA-funded nulling and imaging instrument designed to coherently combine the two 8.4-m primary mirrors of the LBT for high-sensitivity, high-contrast, and high-resolution infrared imaging (1.5-13 micrometer). PHASECam is LBTI's near-infrared camera used to measure tip-tilt and phase variations between the two AO-corrected apertures and provide high-angular resolution observations. We report on the status of the system and describe its on-sky performance measured during the first semester of 2014. With a spatial resolution equivalent to that of a 22.8-meter telescope and the light-gathering power of single 11.8-meter mirror, the co-phased LBT can be considered to be a forerunner of the next-generation extremely large telescopes (ELT)
The HOSTS survey - exozodiacal dust measurements for 30 stars
The Hunt for Observable Signatures of Terrestrial Systems survey searches for dust near the habitable zones (HZs) around nearby, bright main-sequence stars. We use nulling interferometry in the N band to suppress the bright stellar light and to probe for low levels of HZ dust around the 30 stars observed so far. Our overall detection rate is 18%, including four new detections, among which are the first three around Sun-like stars and the first two around stars without any previously known circumstellar dust. The inferred occurrence rates are comparable for early-type and Sun-like stars, but decrease from {60}-21+16% for stars with previously detected cold dust to {8}-3+10% for stars without such excess, confirming earlier results at higher sensitivity. For completed observations on individual stars, our sensitivity is five to ten times better than previous results. Assuming a lognormal excess luminosity function, we put upper limits on the median HZ dust level of 13 zodis (95% confidence) for a sample of stars without cold dust and of 26 zodis when focusing on Sun-like stars without cold dust. However, our data suggest that a more complex luminosity function may be more appropriate. For stars without detectable Large Binocular Telescope Interferometer (LBTI) excess, our upper limits are almost reduced by a factor of two, demonstrating the strength of LBTI target vetting for future exo-Earth imaging missions. Our statistics are limited so far, and extending the survey is critical to informing the design of future exo-Earth imaging surveys
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The HOSTS Survey for Exozodiacal Dust: Preliminary results and future prospects
[abridged] The presence of large amounts of dust in the habitable zones of
nearby stars is a significant obstacle for future exo-Earth imaging missions.
We executed an N band nulling interferometric survey to determine the typical
amount of such exozodiacal dust around a sample of nearby main sequence stars.
The majority of our data have been analyzed and we present here an update of
our ongoing work. We find seven new N band excesses in addition to the high
confidence confirmation of three that were previously known. We find the first
detections around Sun-like stars and around stars without previously known
circumstellar dust. Our overall detection rate is 23%. The inferred occurrence
rate is comparable for early type and Sun-like stars, but decreases from 71%
[+11%/-20%] for stars with previously detected mid- to far-infrared excess to
11% [+9%/-4%] for stars without such excess, confirming earlier results at high
confidence. For completed observations on individual stars, our sensitivity is
five to ten times better than previous results. Assuming a lognormal luminosity
function of the dust, we find upper limits on the median dust level around all
stars without previously known mid to far infrared excess of 11.5 zodis at 95%
confidence level. The corresponding upper limit for Sun-like stars is 16 zodis.
An LBTI vetted target list of Sun-like stars for exo-Earth imaging would have a
corresponding limit of 7.5 zodis. We provide important new insights into the
occurrence rate and typical levels of habitable zone dust around main sequence
stars. Exploiting the full range of capabilities of the LBTI provides a
critical opportunity for the detailed characterization of a sample of
exozodiacal dust disks to understand the origin, distribution, and properties
of the dust.GMK is supported by the Royal Society as a Royal Society University Research Fellow. AS is partially supported by funding from the Center for Exoplanets and Habitable Worlds. The Center for Exoplanets and
Habitable Worlds is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium. JMS is supported by NASA through Hubble Fellowship grant HSTHF2-51398.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555
The HOSTS survey: evidence for an extended dust disk and constraints on the presence of giant planets in the Habitable Zone of Leo
The young (50-400 Myr) A3V star Leo is a primary target to study the
formation history and evolution of extrasolar planetary systems as one of the
few stars with known hot (1600K), warm (600K), and
cold (120K) dust belt components. In this paper, we present deep
mid-infrared measurements of the warm dust brightness obtained with the Large
Binocular Telescope Interferometer (LBTI) as part of its exozodiacal dust
survey (HOSTS). The measured excess is 0.47\%0.050\% within the central
1.5 au, rising to 0.81\%0.026\% within 4.5 au, outside the habitable zone
of ~Leo. This dust level is 50 10 times greater than in the solar
system's zodiacal cloud. Poynting-Robertson drag on the cold dust detected by
Spitzer and Herschel under-predicts the dust present in the habitable zone of
~Leo, suggesting an additional delivery mechanism (e.g.,~comets) or an
additional belt at 5.5 au. A model of these dust components is provided
which implies the absence of planets more than a few Saturn masses between
5 au and the outer belt at 40 au. We also observationally constrain
giant planets with the LBTI imaging channel at 3.8~m wavelength. Assuming
an age of 50 Myr, any planet in the system between approximately 5 au to 50 au
must be less than a few Jupiter masses, consistent with our dust model. Taken
together, these observations showcase the deep contrasts and detection
capabilities attainable by the LBTI for both warm exozodiacal dust and giant
exoplanets in or near the habitable zone of nearby stars.Comment: 11 pages, 9 figures, accepted for publication in Astronomical Journa
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