Influence of Dust Grain Evolution on the Structure of Protoplanetary Disks.

he formation and composition of planets is a direct consequence of the processing of solid dust particles in protoplanetary disks: e.g. grain growth, dust settling, crystallization, and segregation of different dust species. Understanding the connections between these effects and how they vary as a function of time is the first step to producing a map of how planet-forming materials are distributed in disks, providing initial conditions for planet formation and evolution models. These will be necessary to analyze the composition and migration history of increasingly large numbers of confirmed exoplanets. Here I present near-, mid-, and far-infrared observations of young protoplanetary disks and their surroundings to identify when grain processing starts and how far it proceeds in the first 1-2Myr, by which time planet formation is observed. Using Spitzer IRS 5-40um spectra, I construct an extinction curve for molecular clouds, which I use to measure dust processing in IRS spectra of the youngest disks (<1Myr) in the Ophiuchus star-forming region. I then develop a method, using 1-5um (NASA IRTF SpeX), to extract the inner disk excess from these systems and determine the dust properties of that region, finding strong evidence for increased grain growth and settling in the inner disk relative the the outer disk. Fitting this excess using radiative transfer disk structure models suggests a grain-size limit of ~10um in the midplane due to accretion heating in the inner 0.5AU. Iron-rich dust was required to fit the inner disk excess. In Herschel PACS spectra, I detect water ice originating in the disk upper layers, below the photodesorption layer. At half-solar abundance, these detections indicate settling of icy grains. There is evidence of radial structure in the snowline in some of these disks, which combined with the implications of the vertical iron gradient in the inner disk suggests strong spatially variable gas compositions. This has implications for the type of molecules expected to be detectable in the atmospheres of planets forming there. Further work, including interferometry and scattered light observations, are necessary to fully map the distribution of planetary building blocks in these disks at all ages.PHDAstronomy and AstrophysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/108774/1/melisma_1.pd

Orientation and morphology of Pt nanoparticles in γ-alumina processed via ion implantation and thermal annealing

Structure and chemistry of metal/metal-oxide interfaces are critical for many catalytic processes and sensing. Pristine interfaces of Pt and γ -Al2O3 were fabricated using high-energy ion implantation and thermal processing. Amorphous regions of alumina develop in single crystal α-alumina during Pt+ implantation and an 800 °C thermal treatment crystalizes amorphized alumina to γ -Al2O3 and allows Pt ions to precipitate within the developing γ -alumina, yielding Pt nanoparticle tetrahedra terminated by {111} surfaces. The phase of alumina that developed and the distribution, morphology, and orientation of Pt nanoparticles was determined using x-ray diffraction, Rutherford backscattering spectrometry, transmission electron microscopy and scanning transmission electron microscopy

Spitzer Spectroscopy of the Circumprimary Disk in the Binary Brown Dwarf 2MASS J04414489+2301513

Using the Spitzer Infrared Spectrograph, we have performed mid-infrared spectroscopy on the young binary brown dwarf 2MASS J04414489+2301513 (15 AU) in the Taurus star-forming region. The spectrum exhibits excess continuum emission that likely arises from a circumstellar disk around the primary. Silicate emission is not detected in these data, indicating the presence of significant grain growth. This is one of the few brown dwarf disks at such a young age (~1 Myr) that has been found to lack silicate emission. To quantitatively constrain the properties of the disk, we have compared the spectral energy distribution of 2MASS J04414489+2301513 to the predictions of our vertical structure codes for irradiated accretion disks. Our models suggest that the remaining atmospheric grains of moderately depleted layers may have grown to a size of ##IMG## [http://ej.iop.org/icons/Entities/gsim.gif] {gsim} 5 _m. In addition, our model fits indicate an outer radius of 0.2-0.3 AU for the disk. The small size of this circumprimary disk could be due to truncation by the secondary. The absence of an outer disk containing a reservoir of small, primordial grains, combined with a weak turbulent mechanism, may be responsible for the advanced grain growth in this disk.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90835/1/2041-8205_726_1_L3.pd

Gestational weight gain in 4 low- and middle-income countries and associations with birth outcomes: A secondary analysis of the women first trial

Background: Adequate gestational weight gain (GWG) is essential for healthy fetal growth. However, in low- and middle-income countries, where malnutrition is prevalent, little information is available about GWG and how it might be modified by nutritional status and interventions.Objective: We describe GWG and its associations with fetal growth and birth outcomes. We also examined the extent to which prepregnancy BMI, and preconception and early weight gain modify GWG, and its effects on fetal growth.Methods: This was a secondary analysis of the Women First Trial, including 2331 women within the Democratic Republic of Congo (DRC), Guatemala, India, and Pakistan, evaluating weight gain from enrollment to ∼12 weeks of gestation and GWG velocity (kg/wk) between ∼12 and 32 weeks of gestation. Adequacy of GWG velocity was compared with 2009 Institute of Medicine recommendations, according to maternal BMI. Early weight gain (EWG), GWG velocity, and adequacy of GWG were related to birth outcomes using linear and Poisson models.Results: GWG velocity (mean ± SD) varied by site: 0.22 ± 0.15 kg/wk in DRC, 0.30 ± 0.23 in Pakistan, 0.31 ± 0.14 in Guatemala, and 0.39 ± 0.13 in India, (P Conclusions: These results underscore the importance of adequate maternal nutrition both before and during pregnancy as a potentially modifiable factor to improve fetal growth

A multicountry randomized controlled trial of comprehensive maternal nutrition supplementation initiated before conception: the Women First trial.

Background: Reported benefits of maternal nutrition supplements commenced during pregnancy in low-resource populations have typically been quite limited. Objectives: This study tested the effects on newborn size, especially length, of commencing nutrition supplements for women in low-resource populations ≥3 mo before conception (Arm 1), compared with the same supplement commenced late in the first trimester of pregnancy (Arm 2) or not at all (control Arm 3). Methods: Women First was a 3-arm individualized randomized controlled trial (RCT). The intervention was a lipid-based micronutrient supplement; a protein-energy supplement was also provided if maternal body mass index (kg/m2) was(DRC), Guatemala, India, and Pakistan. The primary outcome was length-for-age z score (LAZ), with all anthropometry obtainedDRC, outcomes were determined for all 4 sites from WHO newborn standards (non-gestational-age-adjusted, NGAA) as well as INTERGROWTH-21st fetal standards (3 sites, gestational age-adjusted, GAA). Results: A total of 7387 nonpregnant women were randomly assigned, yielding 2451 births with NGAA primary outcomes and 1465 with GAA outcomes. Mean LAZ and other outcomes did not differ between Arm 1 and Arm 2 using either NGAA or GAA. Mean LAZ (NGAA) for Arm 1 was greater than for Arm 3 (effect size: +0.19; 95% CI: 0.08, 0.30, P = 0.0008). For GAA outcomes, rates of stunting and small-for-gestational-age were lower in Arm 1 than in Arm 3 (RR: 0.69; 95% CI: 0.49, 0.98, P = 0.0361 and RR: 0.78; 95% CI: 0.70, 0.88, P \u3c 0.001, respectively). Rates of preterm birth did not differ among arms. Conclusions: In low-resource populations, benefits on fetal growth-related birth outcomes were derived from nutrition supplements commenced before conception or late in the first trimester. This trial was registered at clinicaltrials.gov as NCT01883193

The Structure of Pre-transitional Protoplanetary Disks I: Radiative Transfer Modeling of the Disk+Cavity in the PDS 70 system

Through detailed radiative transfer modeling, we present a disk+cavity model to simultaneously explain both the SED and Subaru H-band polarized light imaging for the pre-transitional protoplanetary disk PDS 70. Particularly, we are able to match not only the radial dependence, but also the absolute scale, of the surface brightness of the scattered light. Our disk model has a cavity 65 AU in radius, which is heavily depleted of sub-micron-sized dust grains, and a small residual inner disk which produces a weak but still optically thick NIR excess in the SED. To explain the contrast of the cavity edge in the Subaru image, a factor of ~1000 depletion for the sub-micron-sized dust inside the cavity is required. The total dust mass of the disk may be on the order of 1e-4 M_sun, only weakly constrained due to the lack of long wavelength observations and the uncertainties in the dust model. The scale height of the sub-micron-sized dust is ~6 AU at the cavity edge, and the cavity wall is optically thick in the vertical direction at H-band. PDS 70 is not a member of the class of (pre-)transitional disks identified by Dong et al. (2012), whose members only show evidence of the cavity in the millimeter-sized dust but not the sub-micron-sized dust in resolved images. The two classes of (pre-)transitional disks may form through different mechanisms, or they may just be at different evolution stages in the disk clearing process.Comment: 28 pages (single column), 7 figures, 1 table, ApJ accepte

Molecules with ALMA at planet-forming scales. XX. The massive disk around GM Aurigae

Funding: K.R.S., K.Z., J.B., J.H., and I.C. acknowledge the support of NASA through Hubble Fellowship Program grants HST-HF2-51419.001, HST-HF2-51401.001, HST-HF2-51427.001-A, HST-HF2-51460.001-A, and HST-HF2-51405.001-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. J.D.I. acknowledges support from the Science and Technology Facilities Council of the United Kingdom (STFC) under ST/T000287/1. C.W. acknowledges financial support from the University of Leeds, STFC and UKRI (grant numbers ST/R000549/1, ST/T000287/1, MR/T040726/1).Gas mass remains one of the most difficult protoplanetary disk properties to constrain. With much of the protoplanetary disk too cold for the main gas constituent, H2, to emit, alternative tracers such as dust, CO, or the H2 isotopologue HD are used. However, relying on disk mass measurements from any single tracer requires assumptions about the tracer's abundance relative to H2 and the disk temperature structure. Using new Atacama Large Millimeter/submillimeter Array (ALMA) observations from the Molecules with ALMA at Planet-forming Scales (MAPS) ALMA Large Program as well as archival ALMA observations, we construct a disk physical/chemical model of the protoplanetary disk GM Aur. Our model is in good agreement with the spatially resolved CO isotopologue emission from 11 rotational transitions with spatial resolution ranging from 0"15 to 0"46 (24-73 au at 159 pc) and the spatially unresolved HD J = 1-0 detection from Herschel. Our best-fit model favors a cold protoplanetary disk with a total gas mass of approximately 0.2 M⊙, a factor of 10 reduction in CO gas inside roughly 100 au and a factor of 100 reduction outside of 100 au. Despite its large mass, the disk appears to be on the whole gravitationally stable based on the derived Toomre Q parameter. However, the region between 70 and 100 au, corresponding to one of the millimeter dust rings, is close to being unstable based on the calculated Toomre Q of <1.7. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.Publisher PDFPeer reviewe

Neurodevelopment, Vision and Auditory Outcomes at Age 2 Years in Offspring of Participants in the ‘Women First’ Maternal Preconception Nutrition Randomised Controlled Trial

BACKGROUND: Maternal nutrition in preconception and early pregnancy influences fetal growth. Evidence for effects of prenatal maternal nutrition on early child development (ECD) in low-income and middle-income countries is limited. OBJECTIVES: To examine impact of maternal nutrition supplementation initiated prior to or during pregnancy on ECD, and to examine potential association of postnatal growth with ECD domains. DESIGN: Secondary analysis regarding the offspring of participants of a maternal multicountry, individually randomised trial. SETTING: Rural Democratic Republic of the Congo, Guatemala, India and Pakistan. PARTICIPANTS: 667 offspring of Women First trial participants, aged 24 months. INTERVENTION: Maternal lipid-based nutrient supplement initiated preconceptionally (arm 1, n=217), 12 weeks gestation (arm 2, n=230) or not (arm 3, n=220); intervention stopped at delivery. MAIN OUTCOME MEASURES: The INTERGROWTH-21st Neurodevelopment Assessment (INTER-NDA) cognitive, language, gross motor, fine motor, positive and negative behaviour scores; visual acuity and contrast sensitivity scores and auditory evoked response potentials (ERP). Anthropometric z-scores, family care indicators (FCI) and sociodemographic variables were examined as covariates. RESULTS: No significant differences were detected among the intervention arms for any INTER-NDA scores across domains, vision scores or ERP potentials. After adjusting for covariates, length-for-age z-score at 24 months (LAZ CONCLUSIONS: Prenatal maternal nutrition supplementation was not associated with any neurodevelopmental outcomes at age 2 years. Maternal education, family environment and LAZ TRIAL REGISTRATION NUMBER: NCT01883193

Risk factors for maternal death and trends in maternal mortality in low- and middle-income countries: a prospective longitudinal cohort analysis

Abstract Background Because large, prospective, population-based data sets describing maternal outcomes are typically not available in low- and middle-income countries, it is difficult to monitor maternal mortality rates over time and to identify factors associated with maternal mortality. Early identification of risk factors is essential to develop comprehensive intervention strategies preventing pregnancy-related complications. Our objective was to describe maternal mortality rates in a large, multi-country dataset and to determine maternal, pregnancy-related, delivery and postpartum characteristics that are associated with maternal mortality. Methods We collected data describing all pregnancies from 2010 to 2013 among women enrolled in the multi-national Global Network for Women’s and Children’s Health Research Maternal and Neonatal Health Registry (MNHR). We reported the proportion of mothers who died per pregnancy and the maternal mortality ratio (MMR). Generalized linear models were used to evaluate the relationship of potential medical and social factors and maternal mortality and to develop point and interval estimates of relative risk associated with these factors. Generalized estimating equations were used to account for the correlation of outcomes within cluster to develop appropriate confidence intervals. Results We recorded 277,736 pregnancies and 402 maternal deaths for an MMR of 153/100,000 live births. We observed an improvement in the total MMR from 166 in 2010 to 126 in 2013. The MMR in Latin American sites (91) was lower than the MMR in Asian (178) and African sites (125). When adjusted for study site and the other variables, no formal education (RR 3.2 [1.5, 6.9]), primary education only (RR 3.4 [1.6, 7.5]), secondary education only (RR 2.5 [1.1, 5.7]), lack of antenatal care (RR 1.8 [1.2, 2.5]), caesarean section delivery (RR 1.9 [1.3, 2.8]), hemorrhage (RR 3.3 [2.2, 5.1]), and hypertensive disorders (RR 7.4 [5.2, 10.4]) were associated with higher risks of death. Conclusions The MNHR identified preventable causes of maternal mortality in diverse settings in low- and middle-income countries. The MNHR can be used to monitor public health strategies and determine their association with reducing maternal mortality. Trial Registration clinicaltrials.gov NCT0107347

Global network for women’s and children’s health research: a system for low-resource areas to determine probable causes of stillbirth, neonatal, and maternal death

Background: Determining cause of death is needed to develop strategies to reduce maternal death, stillbirth, and newborn death, especially for low-resource settings where 98% of deaths occur. Most existing classification systems are designed for high income settings where extensive testing is available. Verbal autopsy or audits, developed as an alternative, are time-intensive and not generally feasible for population-based evaluation. Furthermore, because most classification is user-dependent, reliability of classification varies over time and across settings. Thus, we sought to develop classification systems for maternal, fetal and newborn mortality based on minimal data to produce reliable cause-of-death estimates for low-resource settings. Results: In six low-resource countries (India, Pakistan, Guatemala, DRC, Zambia and Kenya), we evaluated data which are collected routinely at antenatal care and delivery and could be obtained with interview, observation, or basic equipment from the mother, lay-health provider or family to inform causes of death. Using these basic data collected in a standard way, we then developed an algorithm to assign cause of death that could be computer-programmed. Causes of death for maternal (trauma, abortion, hemorrhage, infection and hypertensive disease of pregnancy), stillbirth (birth trauma, congenital anomaly, infection, asphyxia, complications of preterm birth) and neonatal death (congenital anomaly, infection, asphyxia, complications of preterm birth) are based on existing cause of death classifications, and compatible with the World Health Organization International Classification of Disease system. Conclusions: Our system to assign cause of maternal, fetal and neonatal death uses basic data from family or lay-health providers to assign cause of death by an algorithm to eliminate a source of inconsistency and bias. The major strengths are consistency, transparency, and comparability across time or regions with minimal burden on the healthcare system. This system will be an important contribution to determining cause of death in low-resource settings. Keywords: Cause of death classification Maternal mortality Stillbirth Neonatal mortality Low-income Countrie