165 research outputs found
Testing Planet Formation Models with Gaia as Astrometry
In this paper, we first summarize the results of a large-scale double-blind
tests campaign carried out for the realistic estimation of the Gaia potential
in detecting and measuring planetary systems. Then, we put the identified
capabilities in context by highlighting the unique contribution that the Gaia
exoplanet discoveries will be able to bring to the science of extrasolar
planets during the next decade.Comment: 4 pages, 1 figure. To appear in the proceedings of "IAU Symposium 248
- A Giant Step: from Milli- to Micro-arcsecond Astrometry", held in Shanghai,
China, 15-19 Oct. 200
Testing planet formation models with Gaia μas astrometry
In this paper, we first summarize the results of a large-scale double-blind tests campaign carried out for the realistic estimation of the Gaia potential in detecting and measuring planetary systems. Then, we put the identified capabilities in context by highlighting the unique contribution that the Gaia exoplanet discoveries will be able to bring to the science of extrasolar planets during the next decad
Impacto de los sistemas de riego por goteo en arándanos
3-8The experiment examined the effects of different drip irrigation systems in an O'Neal variety of blueberry (Vaccinium corymbosum L). It was contucted at Zarate (33° 41' S and 59° 41' W), Buenos Aires, Argentina. Plants of the experiment were planted in August of 2001, after one year in nursery. The first harvest was realized in October of 2003. The main scope of the experiment was to find the irrigation system which maximized yields. Treatments were: One drip irrigation line with drippers at 40 cm (T1) and two laterals with drippers at 20 cm per row (T2). The experiment was conducted in a completely randomized block design, each one with 5 plants and 5 replications. During the harvest of October and November of 2003, reported yields were 2436 kg ha-1 for the treatment T1 and 4335 kg ha-1 for the treatment T2. Treatments that partially irrigate beds are insufficient to obtain high yields
A Simple Chemical Method for Rendering Wild-Type Yeast Permeable to Brefeldin A That Does Not Require the Presence of an erg6 Mutation
The present work aims to develop a growth medium to render a wild-type strain of Saccharomyces cerevisiae permeable to the antifungal drug Brefeldin A. In the current study, a synthetic medium containing 0.1% L-proline and supplemented with 3.0 × 10(-3)% SDS is employed. When Brefeldin A is added to this medium, a wild-type strain shows increased growth sensitivity and a diminished transport of the amino acid L-leucine. Since Brefeldin A exerts its effect on the endoplasmic reticulum and the Golgi apparatus, the medium permits the study of the drug effect on the intracellular traffic of L-leucine permeases
Gain-of-Function STIM1 L96V Mutation Causes Myogenesis Alteration in Muscle Cells From a Patient Affected by Tubular Aggregate Myopathy
Tubular Aggregate Myopathy (TAM) is a hereditary ultra-rare muscle disorder characterized by muscle weakness and cramps or myasthenic features. Biopsies from TAM patients show the presence of tubular aggregates originated from sarcoplasmic reticulum due to altered Ca2+ homeostasis. TAM is caused by gain-of-function mutations in STIM1 or ORAI1, proteins responsible for Store-Operated-Calcium-Entry (SOCE), a pivotal mechanism in Ca2+ signaling. So far there is no cure for TAM and the mechanisms through which STIM1 or ORAI1 gene mutation lead to muscle dysfunction remain to be clarified. It has been established that post-natal myogenesis critically relies on Ca2+ influx through SOCE. To explore how Ca2+ homeostasis dysregulation associated with TAM impacts on muscle differentiation cascade, we here performed a functional characterization of myoblasts and myotubes deriving from patients carrying STIM1 L96V mutation by using fura-2 cytofluorimetry, high content imaging and real-time PCR. We demonstrated a higher resting Ca2+ concentration and an increased SOCE in STIM1 mutant compared with control, together with a compensatory down-regulation of genes involved in Ca2+ handling (RyR1, Atp2a1, Trpc1). Differentiating STIM1 L96V myoblasts persisted in a mononuclear state and the fewer multinucleated myotubes had distinct morphology and geometry of mitochondrial network compared to controls, indicating a defect in the late differentiation phase. The alteration in myogenic pathway was confirmed by gene expression analysis regarding early (Myf5, Mef2D) and late (DMD, Tnnt3) differentiation markers together with mitochondrial markers (IDH3A, OGDH). We provided evidences of mechanisms responsible for a defective myogenesis associated to TAM mutant and validated a reliable cellular model usefull for TAM preclinical studies
Nanoscale mechanical control of surface electrical properties of manganite films with magnetic nanoparticles
Mechanical control of electrical properties in complex heterostructures, consisting of magnetic FeOx nanoparticles on top of manganite films, is achieved using atomic force microscope AFM based methods. Under applied pressure of the AFM tip, drop of the electrical conductivity is observed inducing an electrically insulating state upon a critical normal load. Current and surface potential maps suggest that the switching process is mainly governed by the flexoelectric field induced at the sample surface. The relaxation process of the electrical surface potential indicates that the diffusion of oxygen vacancies from the bulk of the manganite films towards the sample surface is the dominant relaxation mechanism. The magnetic FeOx nanoparticles, staying attached to the sample surface after the rubbing, protect the underlying manganite films and provide stability of the observed resistive switching effect. The employed mechanical control gives a new freedom in the design of resistive switching devices since it does not depend on the film thickness, and biasing is not neede
Reaching the boundary between stellar kinematic groups and very wide binaries. II. alpha Lib + KU Lib: a common proper motion system in Castor separated by 1.0 pc
Aims: I investigate the gravitational binding of a nearby common proper
motion system in the young Castor moving group (tau ~ 200 Ma), formed by the
bright quadruple star alpha Lib (Zubenelgenubi) and the young solar analog KU
Lib. The system has an exceptionally wide angular separation, of about 2.6 deg,
which corresponds to a projected physical separation of about 1.0 pc. Methods:
I compile basic information of the system and compare its binding energy with
those of other weakly bound systems in the field, and study the physical
separations of resolved multiple systems in Castor. Results: KU Lib has roughly
the same proper motion, parallactic distance, radial velocity, and metallicity
than the young hierarchical quadruple system alpha Lib. Besides, KU Lib also
displays youth features. The resemblance between these basic parameters and the
relatively large estimated binding energy point out that the five stars are
gravitationally bound. KU Lib and alpha Lib constitute the widest known
multiple system at all mass domains, and likely represent the most extreme
example of young wide binaries on the point of being disrupted. Besides, I make
a comprehensive compilation of star candidates in Castor, including new ones.Comment: A&A, in press (v2: language edited
Timed inhibition of CDC7 increases CRISPR-Cas9 mediated templated repair.
Repair of double strand DNA breaks (DSBs) can result in gene disruption or gene modification via homology directed repair (HDR) from donor DNA. Altering cellular responses to DSBs may rebalance editing outcomes towards HDR and away from other repair outcomes. Here, we utilize a pooled CRISPR screen to define host cell involvement in HDR between a Cas9 DSB and a plasmid double stranded donor DNA (dsDonor). We find that the Fanconi Anemia (FA) pathway is required for dsDonor HDR and that other genes act to repress HDR. Small molecule inhibition of one of these repressors, CDC7, by XL413 and other inhibitors increases the efficiency of HDR by up to 3.5 fold in many contexts, including primary T cells. XL413 stimulates HDR during a reversible slowing of S-phase that is unexplored for Cas9-induced HDR. We anticipate that XL413 and other such rationally developed inhibitors will be useful tools for gene modification
Double-blind test program for astrometric planet detection with Gaia
We use detailed simulations of the Gaia observations of synthetic planetary
systems and develop and utilize independent software codes in double-blind mode
to analyze the data, including statistical tools for planet detection and
different algorithms for single and multiple Keplerian orbit fitting that use
no a priori knowledge of the true orbital parameters of the systems. 1) Planets
with astrometric signatures times the single-measurement error
and period yr can be detected reliably, with a very
small number of false positives. 2) At twice the detection limit, uncertainties
in orbital parameters and masses are typically . 3) Over 70% of
two-planet systems with well-separated periods in the range
yr, , and eccentricity are
correctly identified. 4) Favorable orbital configurations have orbital elements
measured to better than 10% accuracy of the time, and the value of the
mutual inclination angle determined with uncertainties \leq 10^{\degr}. 5)
Finally, uncertainties obtained from the fitting procedures are a good estimate
of the actual errors. Extrapolating from the present-day statistical properties
of the exoplanet sample, the results imply that a Gaia with = 8
as, in its unbiased and complete magnitude-limited census of planetary
systems, will measure several thousand giant planets out to 3-4 AUs from stars
within 200 pc, and will characterize hundreds of multiple-planet systems,
including meaningful coplanarity tests. Finally, we put Gaia into context,
identifying several areas of planetary-system science in which Gaia can be
expected to have a relevant impact, when combined with data coming from other
ongoing and future planet search programs.Comment: 32 pages, 24 figures, 6 tables. Accepted for pubolication in A&
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