134 research outputs found
Herschel/PACS Imaging of Protostars in the HH 1-2 Outflow Complex
We present 70 and 160 micron Herschel science demonstration images of a field
in the Orion A molecular cloud that contains the prototypical Herbig-Haro
objects HH 1 and 2, obtained with the Photodetector Array Camera and
Spectrometer (PACS). These observations demonstrate Herschel's unprecedented
ability to study the rich population of protostars in the Orion molecular
clouds at the wavelengths where they emit most of their luminosity. The four
protostars previously identified by Spitzer 3.6-40 micron imaging and
spectroscopy are detected in the 70 micron band, and three are clearly detected
at 160 microns. We measure photometry of the protostars in the PACS bands and
assemble their spectral energy distributions (SEDs) from 1 to 870 microns with
these data, Spitzer spectra and photometry, 2MASS data, and APEX sub-mm data.
The SEDs are fit to models generated with radiative transfer codes. From these
fits we can constrain the fundamental properties of the protostars. We find
luminosities in the range 12-84 L_sun and envelope densities spanning over two
orders of magnitude. This implies that the four protostars have a wide range of
envelope infall rates and evolutionary states: two have dense, infalling
envelopes, while the other two have only residual envelopes. We also show the
highly irregular and filamentary structure of the cold dust and gas surrounding
the protostars as traced at 160 microns.Comment: 6 pages, 4 figures, accepted for publication in the A&A Herschel
special issu
The Effect of Fractal Contact Lenses on Peripheral Refraction in Myopic Model Eyes
Purpose: To test multizone contact lenses in model eyes: Fractal Contact Lenses (FCLs), designed to induce
myopic peripheral refractive error (PRE).
Methods: Zemax ray-tracing software was employed to simulate myopic and accommodation-dependent model
eyes fitted with FCLs. PRE, defined in terms of mean sphere M and 90–180 astigmatism J180, was computed at
different peripheral positions, ranging from 0 to 35 in steps of 5, and for different pupil diameters (PDs).
Simulated visual performance and changes in the PRE were also analyzed for contact lens decentration and
model eye accommodation. For comparison purposes, the same simulations were performed with another
commercially available contact lens designed for the same intended use: the Dual Focus (DF).
Results: PRE was greater with FCL than with DF when both designs were tested for a 3.5 mm PD, and with and
without decentration of the lenses. However, PRE depended on PD with both multizone lenses, with a
remarkable reduction of the myopic relative effect for a PD of 5.5 mm. The myopic PRE with contact lenses
decreased as the myopic refractive error increased, but this could be compensated by increasing the power
of treatment zones. A peripheral myopic shift was also induced by the FCLs in the accommodated model eye.
In regard to visual performance, a myopia under-correction with reference to the circle of least confusion
was obtained in all cases for a 5.5 mm PD. The ghost images, generated by treatment zones of FCL, were
dimmer than the ones produced with DF lens of the same power.
Conclusions: FCLs produce a peripheral myopic defocus without compromising central vision in photopic
conditions. FCLs have several design parameters that can be varied to obtain optimum results: lens diameter,
number of zones, addition and asphericity; resulting in a very promising customized lens for the treatment
of myopia progression.This research was supported by the Ministerio de Economia y Competitividad (grant FIS2011-23175), the Generalitat Valenciana (grant PROMETEO2009-077) and the Universitat Politecnica de Valencia (grant INNOVA SP20120569), Spain.Rodríguez Vallejo, M.; Benlloch Fornés, JI.; Pons Martí, A.; Monsoriu Serra, JA.; Furlan, WD. (2014). The Effect of Fractal Contact Lenses on Peripheral Refraction in Myopic Model Eyes. Current Eye Research. 39(12):1-10. https://doi.org/10.3109/02713683.2014.903498S110391
IL-17RA-Signaling Modulates CD8+ T Cell Survival and Exhaustion During Trypanosoma cruzi Infection
The IL-17 family contributes to host defense against many intracellular pathogens by mechanisms that are not fully understood. CD8+ T lymphocytes are key elements against intracellular microbes, and their survival and ability to mount cytotoxic responses are orchestrated by several cytokines. Here, we demonstrated that IL-17RA-signaling cytokines sustain pathogen-specific CD8+ T cell immunity. The absence of IL-17RA and IL-17A/F during Trypanosoma cruzi infection resulted in increased tissue parasitism and reduced frequency of parasite-specific CD8+ T cells. Impaired IL-17RA-signaling in vivo increased apoptosis of parasite-specific CD8+ T cells, while in vitro recombinant IL-17 down-regulated the pro-apoptotic protein BAD and promoted the survival of activated CD8+ T cells. Phenotypic, functional, and transcriptomic profiling showed that T. cruzi-specific CD8+ T cells derived from IL-17RA-deficient mice presented features of cell dysfunction. PD-L1 blockade partially restored the magnitude of CD8+ T cell responses and parasite control in these mice. Adoptive transfer experiments established that IL-17RA-signaling is intrinsically required for the proper maintenance of functional effector CD8+ T cells. Altogether, our results identify IL-17RA and IL-17A as critical factors for sustaining CD8+ T cell immunity to T. cruzi
Searching for gas emission lines in Spitzer Infrared Spectrograph (IRS) spectra of young stars in Taurus
Our knowledge of circumstellar disks has traditionally been based on studies
of dust. However, gas dominates the disk mass and its study is key to
understand the star and planet formation process. Spitzer can access gas
emission lines in the mid-infrared, providing new diagnostics of the physical
conditions in accretion disks and outflows. We have studied the spectra of 64
pre-main-sequence stars in Taurus using Spitzer/IRS observations. We have
detected H2 (17.03, 28.22 m) emission in 6 objects, [Ne II] (12.81 m)
in 18 objects, and [Fe II] (17.93, 25.99 m) in 7 objects. [Ne II]
detections are found primarily in Class II objects. The luminosity of the [Ne
II] line, is in general higher for objects known to drive jets than for those
without known jets, but the two groups are not statistically distinguishable.
We have searched for correlations between the line luminosities and different
parameters related to the star-disk system. The [Ne II] luminosity is
correlated with X-ray luminosity for Class II objects. The [NeII] luminosity is
correlated with disk mass and accretion rate when the sample is divided into
high and low accretors. We also find correlations between [NeII] luminosity and
mid-IR continuum luminosity and with luminosity of the [O I] (6300 \AA) line,
the latter being an outflow tracer. [Fe II] luminosity correlates with mass
accretion rate. No correlations were found between H2 luminosity and several
tested parameters. Our study reveals a general trend toward accretion-related
phenomena as the origin of the gas emission lines. Shocks in jets and
outflowing material are more likely to play a significant role than shocks in
infalling material. The role of X-ray irradiation is less prominent but still
present for [Ne II], in particular for Class II sources, the lack of
correlation between [Fe II] and [Ne II] points toward different emitting
mechanisms.Comment: 24 pages, 10 figures Accepted for publication in Astronomy and
Astrophysic
TESS Reveals HD 118203 b to be a Transiting Planet
The exoplanet HD 118203 b, orbiting a bright (V = 8.05) host star, was discovered using the radial velocity method by da Silva et al., but was not previously known to transit. Transiting Exoplanet Survey Satellite (TESS) photometry has revealed that this planet transits its host star. Nine planetary transits were observed by TESS, allowing us to measure the radius of the planet to be 1.136^(+0.029)_(-0.028) R_J, and to calculate the planet mass to be 2.166^(+0.074)_(-0.079) M_J. The host star is slightly evolved with an effective temperature of T_(eff) = 5683^(+84)_(-85) K and a surface gravity of log g = 3.889^(+0.017)_(-0.018). With an orbital period of 6.134985^(+0.000029_(-0.000030) days and an eccentricity of 0.314 ± 0.017, the planet occupies a transitional regime between circularized hot Jupiters and more dynamically active planets at longer orbital periods. The host star is among the 10 brightest known to have transiting giant planets, providing opportunities for both planetary atmospheric and asteroseismic studies
Microsatellite instability in colorectal cancer is associated with local lymphocyte infiltration and low frequency of distant metastases
Colorectal carcinomas (CRCs) with high microsatellite instability (MSI-H) share clinicopathological features distinctly different from their microsatellite stable (MSS) counterparts. Unlike MSS cancers, MSI-H CRCs occur predominantly in the right-sided colon and are often characterised by a strong lymphocyte infiltration. A poor differentiation pattern is found in most MSI-H CRCs, even though patients with MSI-H carcinomas seem to have a significantly longer survival after surgical resection. To clarify which factors contribute to the obvious paradoxon of a more favourable prognosis of MSI tumours, several clinical and histopathological features as well as the microsatellite status were evaluated in 120 colorectal cancer cases fulfilling clinical criteria (Bethesda) indicative for familial colorectal cancer. Microsatellite instablity status and lymphocyte infiltration were related to tumour stage and patients' follow-up. Statistical analysis confirmed well-known relations, such as enhanced lymphocyte infiltration accompanied by Crohn's like reaction (CLR) in MSI-H cancers (CLR+ in 27 out of 47 MSI-H vs 14 out of 71 MSS CRCs, P<0.001). However, after stratification for depth of local invasion and penetration of the primary tumour, T3 tumours displaying MSI had a significantly lower rate of distant metastases (M1 in four out of 35 MSI-H vs 20 out of 41 MSS CRCs, P<0.001). A similar tendency was observed for CLR-positive CRCs (M1 in six out of 29 CLR+ vs 17 out of 45 CLR− CRCs, P=0.13). In a logistic regression model, the MSI-H phenotype and the presence of CLR were independent predictors of a low UICC stage (P=0.006 and 0.04, respectively). These data, together with the recent definition of highly immunogenic neo-antigens expressed in MSI-H tumour cells, suggest that MSI-H CRCs elicit a protective host response that may prevent metastasis formation
Toi-1235 b: A keystone super-earth for testing radius valley emergence models around early m dwarfs
Small planets on close-in orbits tend to exhibit envelope mass fractions of
either effectively zero or up to a few percent depending on their size and
orbital period. Models of thermally-driven atmospheric mass loss and of
terrestrial planet formation in a gas-poor environment make distinct
predictions regarding the location of this rocky/non-rocky transition in
period-radius space. Here we present the confirmation of TOI-1235 b (
days, R), a planet whose size and
period are intermediate between the competing model predictions, thus making
the system an important test case for emergence models of the rocky/non-rocky
transition around early M dwarfs ( R,
M). We confirm the TESS planet discovery using
reconnaissance spectroscopy, ground-based photometry, high-resolution imaging,
and a set of 38 precise radial-velocities from HARPS-N and HIRES. We measure a
planet mass of M which implies an iron core
mass fraction of % in the absence of a gaseous envelope. The
bulk composition of TOI-1235 b is therefore consistent with being Earth-like
and we constrain a H/He envelope mass fraction to be % at 90% confidence.
Our results are consistent with model predictions from thermally-driven
atmospheric mass loss but not with gas-poor formation, which suggests that the
former class of processes remain efficient at sculpting close-in planets around
early M dwarfs. Our RV analysis also reveals a strong periodicity close to the
first harmonic of the photometrically-determined stellar rotation period that
we treat as stellar activity, despite other lines of evidence favoring a
planetary origin ( days,
M) that cannot be firmly ruled out by our data
TOI-1235 b: A Keystone Super-Earth For Testing Radius Valley Emergence Models Around Early M Dwarfs
Small planets on close-in orbits tend to exhibit envelope mass fractions of either effectively zero or up to a few percent depending on their size and orbital period. Models of thermally driven atmospheric mass loss and of terrestrial planet formation in a gas-poor environment make distinct predictions regarding the location of this rocky/nonrocky transition in period–radius space. Here we present the confirmation of TOI-1235 b (P = 3.44 days, ), a planet whose size and period are intermediate between the competing model predictions, thus making the system an important test case for emergence models of the rocky/nonrocky transition around early M dwarfs (R s = 0.630 ± 0.015 , M s = 0.640 ± 0.016 ). We confirm the TESS planet discovery using reconnaissance spectroscopy, ground-based photometry, high-resolution imaging, and a set of 38 precise radial velocities (RVs) from HARPS-N and HIRES. We measure a planet mass of , which implies an iron core mass fraction of % in the absence of a gaseous envelope. The bulk composition of TOI-1235 b is therefore consistent with being Earth-like, and we constrain an H/He envelope mass fraction to be \u3c0.5% at 90% confidence. Our results are consistent with model predictions from thermally driven atmospheric mass loss but not with gas-poor formation, suggesting that the former class of processes remains efficient at sculpting close-in planets around early M dwarfs. Our RV analysis also reveals a strong periodicity close to the first harmonic of the photometrically determined stellar rotation period that we treat as stellar activity, despite other lines of evidence favoring a planetary origin ( days, ) that cannot be firmly ruled out by our data
A large sub-Neptune transiting the thick-disk M4 V TOI-2406
We thank the anonymous referee for their corrections and help in improving the paper. We warmly thank the entire technical staff of the Observatorio Astronomico Nacional at San Pedro Martir in Mexico for their unfailing support to SAINT-EX operations, namely: E. Cadena, T. Calvario, E. Colorado, B. Garcia, G. Guisa, A. Franco, L. Figueroa, B. Hernandez, J. Herrera, E. Lopez, E. Lugo, B. Martinez, J. M. Nunez, J. L. Ochoa, M. Pereyra, F. Quiroz, T. Verdugo, I. Zavala. B.V.R. thanks the Heising-Simons Foundation for support. Y.G.M.C acknowledges support from UNAM-PAPIIT IG-101321. B.-O. D. acknowledges support from the Swiss National Science Foundation (PP00P2-163967 and PP00P2-190080). R.B. acknowledges the support from the Swiss National Science Foundation under grant P2BEP2_195285. M.N.G. acknowledges support from MIT's Kavli Institute as a Juan Carlos Torres Fellow. A.H.M.J.T acknowledges funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement nffi 803193/BEBOP), from the MERAC foundation, and from the Science and Technology Facilities Council (STFC; grant nffi ST/S00193X/1). T.D. acknowledges support from MIT's Kavli Institute as a Kavli postdoctoral fellow Part of this work received support from the National Centre for Competence in Research PlanetS, supported by the Swiss National Science Foundation (SNSF). The research leading to these results has received funding from the ARC grant for Concerted Research Actions, financed by the Wallonia-Brussels Federation. TRAPPIST is funded by the Belgian Fund for Scientific Research (Fond National de la Recherche Scientifique, FNRS) under the grant FRFC 2.5.594.09.F, with the participation of the Swiss National Science Fundation (SNF). M.G. and E.J. are F.R.S.-FNRS Senior Research Associate. This publication benefits from the support of the French Community of Belgium in the context of the FRIA Doctoral Grant awarded to MT. We acknowledge the use of public TESS data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. We acknowledge the use of public TESS Alert data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products. Funding for the TESS mission is provided by NASA's Science Mission Directorate. This research has made use of the Exoplanet Follow-up Observation Program website, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This paper includes data collected by the TESS mission that are publicly available from the Mikulski Archive for Space Telescopes (MAST). We thank the TESS GI program G03274 PI, Ryan Cloutier, for proposing the target of this work for 2-min-cadence observations in Sector 30. This work is based upon observations carried out at the Observatorio Astronomico Nacional on the Sierra de San Pedro Martir (OAN-SPM), Baja California, Mexico. This work makes use of observations from the LCOGT network. Part of the LCOGT telescope time was granted by NOIRLab through the Mid-Scale Innovations Program (MSIP). MSIP is funded by NSF. This work includes data collected at the Vatican Advanced Technology Telescope (VATT) on Mt. Graham.
This paper includes data taken on the EDEN telescope network. We acknowledge support from the Earths in Other Solar Systems Project (EOS) and Alien Earths (grant numbers NNX15AD94G and 80NSSC21K0593), sponsored by NASA. Some of the observations in the paper made use of the High-Resolution Imaging instrument Zorro (Gemini program GS-2020B-LP-105). Zorro was funded by the NASA Exoplanet Exploration Program and built at the NASA Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley. Zorro was mounted on the Gemini South telescope of the international Gemini Observatory, a program of NSF's OIR Lab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. on behalf of the Gemini partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigacion y Desarrollo (Chile), Ministerio de Ciencia, Tecnologia e Innovacion (Argentina), Ministerio da Ciencia, Tecnologia, Inovacoes e Comunicacoes (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This work made use of the following Python packages: astropy (Astropy Collaboration 2013, 2018), lightkurve (Lightkurve Collaboration 2018), matplotlib (Hunter 2007), pandas (Wes McKinney 2010), seaborn (Waskom & The Seaborn Development team 2021), scipy (Virtanen et al. 2020) and numpy (Harris et al. 2020).Context. Large sub-Neptunes are uncommon around the coolest stars in the Galaxy and are rarer still around those that are metal-poor. However, owing to the large planet-to-star radius ratio, these planets are highly suitable for atmospheric study via transmission spectroscopy in the infrared, such as with JWST. Aims. Here we report the discovery and validation of a sub-Neptune orbiting the thick-disk, mid-M dwarf star TOI-2406. The star's low metallicity and the relatively large size and short period of the planet make TOI-2406 b an unusual outcome of planet formation, and its characterisation provides an important observational constraint for formation models. Methods. We first infer properties of the host star by analysing the star's near-infrared spectrum, spectral energy distribution, and Gaia parallax. We use multi-band photometry to confirm that the transit event is on-target and achromatic, and we statistically validate the TESS signal as a transiting exoplanet. We then determine physical properties of the planet through global transit modelling of the TESS and ground-based time-series data. Results. We determine the host to be a metal-poor M4 V star, located at a distance of 56 pc, with properties T-eff = 3100 +/- 75 K, M-* = 0.162 +/- 0.008M(circle dot), R-* = 0.202 +/- 0.011R(circle dot), and [Fe/H] = -0.38 +/- 0.07, and a member of the thick disk. The planet is a relatively large sub-Neptune for the M-dwarf planet population, with R-p = 2.94 +/- 0.17R(circle plus) and P= 3.077 d, producing transits of 2% depth. We note the orbit has a non-zero eccentricity to 3 sigma, prompting questions about the dynamical history of the system. Conclusions. This system is an interesting outcome of planet formation and presents a benchmark for large-planet formation around metal-poor, low-mass stars. The system warrants further study, in particular radial velocity follow-up to determine the planet mass and constrain possible bound companions. Furthermore, TOI-2406 b is a good target for future atmospheric study through transmission spectroscopy. Although the planet's mass remains to be constrained, we estimate the S/N using amass-radius relationship, ranking the system fifth in the population of large sub-Neptunes, with TOI-2406 b having a much lower equilibrium temperature than other spectroscopically accessible members of this population.Heising-Simons FoundationPrograma de Apoyo a Proyectos de Investigacion e Innovacion Tecnologica (PAPIIT)Universidad Nacional Autonoma de Mexico IG-101321Swiss National Science Foundation (SNSF)European Commission PP00P2-163967
PP00P2-190080
P2BEP2_195285MIT's Kavli Institute as a Juan Carlos Torres FellowEuropean Research Council (ERC) nffi 803193/BEBOPMERAC foundationUK Research & Innovation (UKRI)Science & Technology Facilities Council (STFC)Science and Technology Development Fund (STDF) nffi ST/S00193X/1MIT's Kavli Institute as a Kavli postdoctoral fellowSwiss National Science Foundation (SNSF)Australian Research CouncilFonds de la Recherche Scientifique - FNRS FRFC 2.5.594.09.FSwiss National Science Foundation (SNSF)French Community of Belgium in the context of the FRIA Doctoral GrantNASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research CenterNASA's Science Mission DirectorateNational Aeronautics and Space Administration under the Exoplanet Exploration ProgramTESS GI program G03274National Science Foundation (NSF)Earths in Other Solar Systems Project (EOS)Alien Earths - NASA NNX15AD94G
80NSSC21K0593High-Resolution Imaging instrument Zorro (Gemini program) GS-2020B-LP-105NASA Exoplanet Exploration ProgramNational Aeronautics & Space Administration (NASA)National Science Foundation (NSF
The Microphenotron: a robotic miniaturized plant phenotyping platform with diverse applications in chemical biology
Background
Chemical genetics provides a powerful alternative to conventional genetics for understanding gene function. However, its application to plants has been limited by the lack of a technology that allows detailed phenotyping of whole-seedling development in the context of a high-throughput chemical screen. We have therefore sought to develop an automated micro-phenotyping platform that would allow both root and shoot development to be monitored under conditions where the phenotypic effects of large numbers of small molecules can be assessed.
Results
The ‘Microphenotron’ platform uses 96-well microtitre plates to deliver chemical treatments to seedlings of Arabidopsis thaliana L. and is based around four components: (a) the ‘Phytostrip’, a novel seedling growth device that enables chemical treatments to be combined with the automated capture of images of developing roots and shoots; (b) an illuminated robotic platform that uses a commercially available robotic manipulator to capture images of developing shoots and roots; (c) software to control the sequence of robotic movements and integrate these with the image capture process; (d) purpose-made image analysis software for automated extraction of quantitative phenotypic data. Imaging of each plate (representing 80 separate assays) takes 4 min and can easily be performed daily for time-course studies. As currently configured, the Microphenotron has a capacity of 54 microtitre plates in a growth room footprint of 2.1 m², giving a potential throughput of up to 4320 chemical treatments in a typical 10 days experiment. The Microphenotron has been validated by using it to screen a collection of 800 natural compounds for qualitative effects on root development and to perform a quantitative analysis of the effects of a range of concentrations of nitrate and ammonium on seedling development.
Conclusions
The Microphenotron is an automated screening platform that for the first time is able to combine large numbers of individual chemical treatments with a detailed analysis of whole-seedling development, and particularly root system development. The Microphenotron should provide a powerful new tool for chemical genetics and for wider chemical biology applications, including the development of natural and synthetic chemical products for improved agricultural sustainability
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