13 research outputs found
A reconstruction problem related to balance equations II: The general case
No full textAbstractA modified k-deck of a graph G, first introduced in (Krasikov and Roditty, 1987), is obtained by removing k edges of G in all possible ways, and adding k (not necessarily new) edges in all possible ways. Krasikov and Roditty asked if it was possible to construct the usual k-edge deck of a graph from its modified k-deck. In (Thatte, to appear), the author solved this problem for the case when k = 1. In this paper, the problem is completely solved for arbitrary k. The proof makes use of the k-edge version of Lovász's result and the eigenvalues of certain matrix related to the Johnson graph
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems. III. Aperture Masking Interferometric Observations of the Star HIP 65426 at 3.8μm
No full textRay, Shrishmoy et al.-- Full list of authors: Ray, Shrishmoy; Sallum, Steph; Hinkley, Sasha; Sivaramkrishnan, Anand; Cooper, Rachel; Kammerer, Jens; Greebaum, Alexandra Z.; Thatte, Deeparshi; Stolker, Tomas; Lazzoni, Cecilia; Tokovinin, Andrei; de Furio, Matthew; Factor, Samuel; Meyer, Michael; Stone, Jordan M.; Carter, Aarynn; Biller, Beth; Skemer, Andrew; Suárez, Genaro; Leisenring, Jarron M.; Perrin, Marshall D.; Kraus, Adam L.; Absil, Olivier; Balmer, William O.; Boccaletti, Anthony; Bonavita, Mariangela; Bonnefoy, Mickael; Booth, Mark; Bowler, Brendan P.; Briesemeister, Zackery W.; Bryan, Marta L.; Calissendorff, Per; Cantalloube, Faustine; Chauvin, Gael; Chen, Christine H.; Choquet, Elodie; Christiaens, Valentin; Cugno, Gabriele; Currie, Thayne; Danielski, Camilla; Dupuy, Trent J.; Faherty, Jacqueline K.; Fitzgerald, Michael P.; Fortney, Jonathan J.; Franson, Kyle; Girard, Julien H.; Grady, Carol A.; Gonzales, Eileen C.; Henning, Thomas; Hines, Dean C.; Hoch, Kielan K. W.; Hood, Callie E.; Howe, Alex R.; Janson, Markus; Kalas, Paul; Kennedy, Grant M.; Kenworthy, Matthew A.; Kervella, Pierre; Kuzuhara, Masayuki; Lagrange, Anne-Marie; Lagage, Pierre-Olivier; Lawson, Kellen; Lew, Ben W. P.; Liu, Michael C.; Liu, Pengyu; Llop-Sayson, Jorge; Lloyd, James P.; Macintosh, Bruce; Marino, Sebastian; Marley, Mark S.; Marois, Christian; Martinez, Raquel A.; Matthews, Brenda C.; Matthews, Elisabeth C.; Mawet, Dimitri; Mazoyer, Johan; McElwain, Michael W.; Metchev, Stanimir; Meyer, Michael R.; Miles, Brittany E.; Millar-Blanchaer, Maxwell A.; Molliere, Paul; Moran, Sarah E.; Morley, Caroline V.; Mukherjee, Sagnick; Palma-Bifani, Paulina; Pantin, Eric; Patapis, Polychronis; Petrus, Simon; Pueyo, Laurent; Quanz, Sascha P.; Quirrenbach, Andreas; Rebollido, Isabel; Adams Redai, Jea; Ren, Bin B.; Rickman, Emily; Samland, Matthias; Schlieder, Joshua E.; Schneider, Glenn; Stapelfeldt, Karl R.; Tamura, Motohide; Tan, Xianyu; Uyama, Taichi; Vigan, Arthur; Vasist, Malavika; Vos, Johanna M.; Wagner, Kevin; Wang, Jason J.; Ward-Duong, Kimberly; Whiteford, Niall; Wolff, Schuyler G.; Worthen, Kadin; Wyatt, Mark C.; Ygouf, Marie; Zhang, Xi; Zhang, Keming; Zhang, Zhoujian; Zhou, Yifan; Zurlo, Alice; Sargent, B. A.; Theissen, Christopher A.; Manjavacas, Elena; Lueber, Anna; Kitzmann, Daniel; Sutlieff, Ben J.; Betti, Sarah K.We present aperture masking interferometry (AMI) observations of the star HIP 65426 at 3.8 μm, as part of the JWST Direct Imaging Early Release Science program, obtained using the Near Infrared Imager and Slitless Spectrograph instrument. This mode provides access to very small inner working angles (even separations slightly below the Michelson limit of 0.5λ/D for an interferometer), which are inaccessible with the classical inner working angles of the JWST coronagraphs. When combined with JWST's unprecedented infrared sensitivity, this mode has the potential to probe a new portion of parameter space across a wide array of astronomical observations. Using this mode, we are able to achieve a 5σ contrast of ΔmF380M ∼ 7.62 ± 0.13 mag relative to the host star at separations ≳0
07, and the contrast deteriorates steeply at separations ≲0
07. However, we detect no additional companions interior to the known companion HIP 65426b (at separation ∼0
82 or
). Our observations thus rule out companions more massive than 10–12 MJup at separations ∼10–20 au from HIP 65426, a region out of reach of ground- or space-based coronagraphic imaging. These observations confirm that the AMI mode on JWST is sensitive to planetary mass companions at close-in separations (≳0
07), even for thousands of more distant stars at ∼100 pc, in addition to the stars in the nearby young moving groups and associations, as stated in previous works. This result will allow the planning and successful execution of future observations to probe the inner regions of nearby stellar systems, opening an essentially unexplored parameter space. © 2025. The Author(s).This work is based on observations made with the NASA/
ESA/CSA JWST and obtained from the Mikulski Archive for
Space Telescopes at the Space Telescope Science Institute. The
specific observations analyzed can be accessed via 10.17909/
8by2-x206. We are truly grateful for the countless hours that
thousands of people have devoted to the design, construction,
and commissioning of JWST. We thank the anonymous referee
for comments that have been crucial toward the improvement
of this Letter. This project was supported by a grant from
STScI (JWST-ERS-01386) under NASA contract NAS5-
03127. S.R. was supported by the Global Excellence Award
at the University of Exeter. This work is based in part on
observations obtained at the Southern Astrophysical Research
(SOAR) telescope, which is a joint project of the Ministério da
Ciência, Tecnologia e Inovações (MCTI/LNA) of Brasil, the
US National Science Foundation’s NOIRLab, the University of
North Carolina at Chapel Hill (UNC), and Michigan State
University (MSU). This work has also made use of the
SPHERE Data Centre, jointly operated by OSUG/IPAG
(Grenoble), PYTHEAS/LAM/CeSAM (Marseille), OCA/
Lagrange (Nice), Observatoire de Paris/LESIA (Paris), and
Observatoire de Lyon/CRAL, as well as being supported by a
grant from Labex OSUG@2020 (Investissements d’avenir—
ANR10 LABX56). This work has benefited from the 2022
Exoplanet Summer Program in the Other Worlds Laboratory
(OWL) at the University of California, Santa Cruz, a program
funded by the Heising–Simons Foundation.Peer reviewe
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The Near Infrared Imager and Slitless Spectrograph for the James Webb Space Telescope. I. Instrument Overview and In-flight Performance
No full textThe Near-Infrared Imager and Slitless Spectrograph (NIRISS) is the science module of the Canadian-built Fine Guidance Sensor onboard the James Webb Space Telescope (JWST). NIRISS has four observing modes: (1) broadband imaging featuring seven of the eight NIRCam broadband filters, (2) wide-field slitless spectroscopy at a resolving power of ∼150 between 0.8 and 2.2 μm, (3) single-object cross-dispersed slitless spectroscopy (SOSS) enabling simultaneous wavelength coverage between 0.6 and 2.8 μm at R ∼ 700, a mode optimized for exoplanet spectroscopy of relatively bright (J < 6.3) stars and (4) aperture masking interferometry (AMI) between 2.8 and 4.8 μm enabling high-contrast (∼10−3 − 10−4) imaging at angular separations between 70 and 400 mas for relatively bright (M < 8) sources. This paper presents an overview of the NIRISS instrument, its design, its scientific capabilities, and a summary of in-flight performance. NIRISS shows significantly better response shortward of ∼2.5 μm resulting in 10%-40% sensitivity improvement for broadband and low-resolution spectroscopy compared to pre-flight predictions. Two time-series observations performed during instrument commissioning in the SOSS mode yield very stable spectro-photometry performance within ∼10% of the expected noise. The first space-based companion detection of the tight binary star AB Dor AC through AMI was demonstrated. © 2023. The Author(s). Published by IOP Publishing Ltd on behalf of the Astronomical Society of the Pacific (ASP). All rights reserved.Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
The Impact of Aid on Maternal and Reproductive Health: A Systematic Review to Evaluate the Effect of Aid on the outcomes of Millennium Development Goal 5:The Impact of Aid on Maternal and Reproductive Health
No full textBackgroundThe Millennium Development Goal 5 (MDG 5) aims to improve maternal andreproductive health outcomes by: a) reducing the maternal mortality ratio by 75%; and b) achieving universal access to reproductive healthcare, by 2015. Current estimates suggest that only 23 countries out of 181 are likely to reduce maternal mortality by 75%. The adoption of the Paris Declaration on Aid Effectiveness in 2005 represented a global agenda to improve aid management and delivery, partly in order to address the slow progress towards the MDGs. In 2008, the Principles set out in the Paris Declaration to guide changes in international aid were re-affirmed in the Accra Agenda for Action.This review assesses available evidence of how aid delivered under the Principles adopted in the Paris Declaration is impacting upon development outcomes, focusing specifically on maternal and reproductive health (MDG 5). The review question is: What is the evidence of the impact on MDG 5 outcomes of delivering aid in line with Paris and Accra aid effectiveness principles? How does this compare to the evidence of the impact of aid in general on MDG 5 outcomes?Methods and ResultsThe review involved a comprehensive search of the literature to identify studiesthat met specific criteria. The studies had to address maternal and reproductive health in developing countries, had to concern activities funded by international aid, and had to provide evidence of the impact of the aid on maternal and reproductive health. By using broad criteria on the MDG 5 indicators and broad definitions of aid we made the review as inclusive as possible. An initial yield of 209 reports was screened using clearly defined inclusion and exclusion criteria to produce a total of 30 causal and correlation studies for synthesis and analysis.The review identified discernible gaps in the evidence base about the impact of aid on MDG 5, which are of concern if these targets are to be met by 2015. The studies suggest that aid-funded health care interventions, whether delivered using the Paris Principles or not, might be associated with better health outcomes. However, these findings should be interpreted with caution due to methodological limitations associated with the study designs. The data do not allow for a meaningful comparison of outcomes between aid delivered according to the Paris Principles and aid delivered outside this framework.Conclusions and RecommendationsOn systematic reviews and research methodology:There was considerable variation in the design and objectives of the studiesincluded. Impact evaluation literature asserts that studies based onexperimental design (e.g. randomised control trials) present the most plausibleevidence of impact. A more flexible approach to evaluating the impact of aid isrequired in order to capture contextual factors affecting how aid works.On evaluating on aid effectiveness:Future primary studies seeking to explore the impact of aid on outcomes inspecific sectors need to provide full information about the aid intervention.The impact of aid on maternal and reproductive health 2Likewise studies on aid effectiveness and aid modalities need to go further inproviding robust data for evaluating outcomes.On interventions in maternal and reproductive health:Before claims about cause and effect can be made, we need robust baselinedata to couple with later data. Most of the studies reviewed had a strongemphasis on healthcare interventions. Other factors that affect maternal andreproductive health, such as gender politics, income and class are neglected byrobust research, which if undertaken, could add significant insight into ourunderstanding of the interactions that shape maternal and reproductive healthin developing countries and consequently our efforts to improve outcomes andassess our interventions
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Effects of organophosphates on neural and purified liver tissue transglutaminase
No full textTransglutaminase 2 (TGase 2) is a multifunctional calcium dependent enzyme that catalyzes protein modifications. TGase 2 is essential in neuronal cell differentiation and it has been reported that certain organophosphates are able to inhibit this process, and the organophosphate phenyl saligenin compound also disrupts TGase 2 activity. It has also been shown that the organophosphates chlorpyrifos (CPF) and chlorpyrifos oxon (CPFO), which cause developmental neurotoxicity, provoke several changes in differentiating rat C6 glioma cells at different levels. The aims of this thesis were to analyse the effects of CPF and CPFO on the TGases present in differentiating rat C6 glioma cells, to develop a new method for the purification of TGase 2 from guinea pig liver, to study possible direct interactions between TGase 2 and esterase inhibitors and to analyze a possible pathway for the externalisation of TGase 2.
In the presence of sodium butyrate, rat C6 glial cells differentiated into an astrocyte phenotype. Differentiation of the cells was associated with an increase in the activity, protein levels and gene expression of TGase 2. Differentiation in the presence of CPF or CPFO generated an increase in the activity of TGase 2, a decrease in its levels of gene expression but had no effect on the protein levels. These effects could be associated with a direct interaction between the organophosphates and TGase 2.
Chromatographic methods were developed to purify TGase 2 from guinea pig liver and the most effective one was a combination of ion exchange chromatography, protamine sulfate precipitation and hydrophobic interaction chromatography (HIC). The level of purity and yield obtained were superior to that of previously published methods. Furthermore, the final step of HIC could be applied directly to commercially available TGase 2 for the production of a highly purified TGase 2 sample.
When TGase 2 purified in this manner was assayed in the presence of CPF and CPFO, enzyme activity was observed to increase significantly, suggesting a direct interaction with TGase 2. By contrast, phenyl saligenin phosphate was found to inhibit TGase activity in vitro, which suggests a direct effect that may involve a different binding site and/or mechanism to CPF or CPFO. The aspartyl protease inhibitor pepstatin A was also able to inhibit directly TGase activity in vitro.
The final part of the project involved a short study of the potential association of TGase 2 with exosomes, in order to determine whether the latter might present a means of externalization of this enzyme. Exosomes purified from mouse N2a neuroblastoma cells were found to contain TGase 2, but its localization within the vesicles remains unclear
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems. IV. NIRISS Aperture Masking Interferometry Performance and Lessons Learned
No full textWe present a performance analysis for the aperture masking interferometry (AMI) mode on board the James Webb Space Telescope Near Infrared Imager and Slitless Spectrograph (JWST/NIRISS). Thanks to self-calibrating observables, AMI accesses inner working angles down to and even within the classical diffraction limit. The scientific potential of this mode has recently been demonstrated by the Early Release Science (ERS) 1386 program with a deep search for close-in companions in the HIP 65426 exoplanetary system. As part of ERS 1386, we use the same data set to explore the random, static, and calibration errors of NIRISS AMI observables. We compare the observed noise properties and achievable contrast to theoretical predictions. We explore possible sources of calibration errors and show that differences in charge migration between the observations of HIP 65426 and point-spread function calibration stars can account for the achieved contrast curves. Lastly, we use self-calibration tests to demonstrate that with adequate calibration NIRISS F380M AMI can reach contrast levels of ∼9–10 mag at ≳λ/D. These tests lead us to observation planning recommendations and strongly motivate future studies aimed at producing sophisticated calibration strategies taking these systematic effects into account. This will unlock the unprecedented capabilities of JWST/NIRISS AMI, with sensitivity to significantly colder, lower-mass exoplanets than lower-contrast ground-based AMI setups, at orbital separations inaccessible to JWST coronagraphy
The \textit{JWST} Early Release Science Program for Direct Observations of Exoplanetary Systems III: Aperture Masking Interferometric Observations of the star HIP\,65426 at
No full textWe present aperture masking interferometry (AMI) observations of the star HIP
65426 at as a part of the \textit{JWST} Direct Imaging Early
Release Science (ERS) program obtained using the Near Infrared Imager and
Slitless Spectrograph (NIRISS) instrument. This mode provides access to very
small inner working angles (even separations slightly below the Michelson limit
of for an interferometer), which are inaccessible with the
classical inner working angles of the \textit{JWST} coronagraphs. When combined
with \textit{JWST}'s unprecedented infrared sensitivity, this mode has the
potential to probe a new portion of parameter space across a wide array of
astronomical observations. Using this mode, we are able to achieve a contrast
of \,mag relative to the host star at a separation
of {\sim}0.07\arcsec but detect no additional companions interior to the
known companion HIP\,65426\,b. Our observations thus rule out companions more
massive than 10{-}12\,\rm{M\textsubscript{Jup}} at separations
from HIP\,65426, a region out of reach of ground or
space-based coronagraphic imaging. These observations confirm that the AMI mode
on \textit{JWST} is sensitive to planetary mass companions orbiting at the
water frost line, even for more distant stars at 100\,pc. This result
will allow the planning and successful execution of future observations to
probe the inner regions of nearby stellar systems, opening essentially
unexplored parameter space.Comment: 15 pages, 9 figures, submitted to ApJ Letter
