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Kingsborough Community College

UniversityBrooklyn, New York, United States

Research output, citation impact, and the most-cited recent papers from Kingsborough Community College (United States). Aggregated across the NobleBlocks index of 300M+ scholarly works.

Total works
1.5K
Citations
27.1K
h-index
79
i10-index
421
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Kingsborough Community College

Top-cited papers from Kingsborough Community College

Comet 81P/Wild 2 Under a Microscope
D. E. Brownlee, P. Tsou, J. Aléon, C. M. O'd. Alexander +4 more
2006· Science922doi:10.1126/science.1135840

The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.

The Provenances of Asteroids, and Their Contributions to the Volatile Inventories of the Terrestrial Planets
C. M. O'd. Alexander, R. Bowden, Marilyn L. Fogel, K. T. Howard +2 more
2012· Science681doi:10.1126/science.1223474

Determining the source(s) of hydrogen, carbon, and nitrogen accreted by Earth is important for understanding the origins of water and life and for constraining dynamical processes that operated during planet formation. Chondritic meteorites are asteroidal fragments that retain records of the first few million years of solar system history. The deuterium/hydrogen (D/H) values of water in carbonaceous chondrites are distinct from those in comets and Saturn's moon Enceladus, implying that they formed in a different region of the solar system, contrary to predictions of recent dynamical models. The D/H values of water in carbonaceous chondrites also argue against an influx of water ice from the outer solar system, which has been invoked to explain the nonsolar oxygen isotopic composition of the inner solar system. The bulk hydrogen and nitrogen isotopic compositions of CI chondrites suggest that they were the principal source of Earth's volatiles.

Non-Native Educators in English Language Teaching
Natasha Lvovich, George Braine
1999· TESOL Quarterly541doi:10.2307/3587894

Contents: Preface. G. Braine, Introduction. Part I: Who We Are. J. Thomas, Voices From the Periphery: Teachers and Issues of Credibility. G. Braine, From the Periphery to the Center: One Teacher's Journey. U.N. Connor, Learning to Write Academic Prose in a Second Language: A Literacy Autobiography. X-M. Li, Writing From the Vantage Point of an Outsider/Insider. C. Kramsch, W.S.E. Lam, Textual Identities: The Importance of Being Non-Native. Part II: Sociopolitical Concerns. A.S. Canagarajah, Interrogating the Speaker Fallacy: Non-Linguistic Roots, Non-Pedagogical Results. N. Amin, Minority Women Teachers of ESL: Negotiating White English. M. Oda, English Only or English Plus? The Language(s) of EFL Organizations. Part III: Implications for Teacher Education. K.K. Samimy, J. Brutt-Griffler, To Be a Native or Speaker: Perceptions of Non-Native Students in a Graduate TESOL Program. L.D. Kamhi-Stein, Preparing Professionals in TESOL: Implications for Teacher Education Programs. J. Liu, From Their Own Perspectives: The Impact of ESL Professionals on Their Students. P. Medgyes, Language Training: A Neglected Area in Teacher Education. D. Liu, Training TESOL Students: Challenges for TESOL Teacher Education in the West.

A model of the thermal processing of particles in solar nebula shocks: Application to the cooling rates of chondrules
S. J. Desch, H. C. Connolly
2002· Meteoritics and Planetary Science365doi:10.1111/j.1945-5100.2002.tb01104.x

Abstract— We present a model for the thermal processing of particles in shock waves typical of the solar nebula. This shock model improves on existing models in that the dissociation and recombination of H 2 and the evaporation of particles are accounted for in their effects on the mass, momentum and energy fluxes. Also, besides thermal exchange with the gas and gas‐drag heating, particles can be heated by absorbing the thermal radiation emitted by other particles. The flow of radiation is calculated using the equations of radiative transfer in a slab geometry. We compute the thermal histories of particles as they encounter and pass through the shock. We apply this shock model to the melting and cooling of chondrules in the solar nebula. We constrain the combinations of shock speed and gas density needed for chondrules to reach melting temperatures, and show that these are consistent with shock waves generated by gravitational instabilities in the protoplanetary disk. After their melting, cooling rates of chondrules in the range 10–1000 K h −1 are naturally reproduced by the shock model. Chondrules are kept warm by the reservoir of hot shocked gas, which cools only as fast as the dust grains and chondrules themselves can radiate away the gas's energy. We predict a positive correlation between the concentration of chondrules in a region and the cooling rates of chondrules in that region. This correlation is supported by the unusually high frequency of (rapidly cooled) barred chondrules among compound chondrules, which must have collided preferentially in regions of high chondrule density. We discuss these and other compelling consistencies between the meteoritic record and the shock wave model of chondrule formation.

Race, ethnicity, gender, and generational factors associated with the coming‐out process among gay, lesbian, and bisexual individuals
Christian Grov, David S. Bimbi, José Nanín, Jeffrey T. Parsons
2006· The Journal of Sex Research329doi:10.1080/00224490609552306

Age at coming out among gay/lesbian/bisexual (GLB) persons and sexual debut with same-gendered partners has typically been investigated in samples that do not reflect the racial and ethnic diversity of these communities. Addressing this limitation, data were collected from a diverse sample of men and women attending large-scale GLB community events in New York and Los Angeles in 2003 (N = 2,733). Compared to older cohorts, younger cohorts (18-24 year olds) of both men and women reported significantly earlier ages for sexual debut with same-gendered partners, and earlier ages for coming out to themselves and to others. Also, women began the process at later ages than men, as they reported coming out to themselves and sexual debut with a same-gender partner approximately two years later than men. There were no racial or ethnic differences in age out to self or others; however, persons of color were less likely to be out to their parents. Service providers, sexuality educators, and researchers should attend to the diversity in experience of coming out among GLB populations as they relate to the individuals gender, age, and racial and ethnic backgrounds.

The CR chondrite clan: Implications for early solar system processes
Alexander N. Krot, Anders Meibom, M. K. Weisberg, Klaus Keil
2002· Meteoritics and Planetary Science233doi:10.1111/j.1945-5100.2002.tb00805.x

Abstract— In this paper, we review the mineralogy and chemistry of calcium‐aluminum‐rich inclusions (CAIs), chondrules, FeNi‐metal, and fine‐grained materials of the CR chondrite clan, including CR, CH, and the metal‐rich CB chondrites Queen Alexandra Range 94411, Hammadah al Hamra 237, Bencubbin, Gujba, and Weatherford. The members of the CR chondrite clan are among the most pristine early solar system materials, which largely escaped thermal processing in an asteroidal setting (Bencubbin, Weatherford, and Gujba may be exceptions) and provide important constraints on the solar nebula models. These constraints include (1) multiplicity of CAI formation; (2) formation of CAIs and chondrules in spatially separated nebular regions; (3) formation of CAIs in gaseous reservoir(s) having 16 O‐rich isotopic compositions; chondrules appear to have formed in the presence of 16 O‐poor nebular gas; (4) isolation of CAIs and chondrules from nebular gas at various ambient temperatures; (5) heterogeneous distribution of 26 Al in the solar nebula; and (6) absence of matrix material in the regions of CAI and chondrule formation.

A Meta-Analytic Review of Preschool Social and Emotional Learning Interventions
Dana Murano, Jeremy Sawyer, Anastasiya A. Lipnevich
2020· Review of Educational Research230doi:10.3102/0034654320914743

This meta-analysis summarized the effects of universal and targeted social and emotional learning (SEL) interventions in 48 studies on the development of social and emotional skills and the reduction of problem behaviors in 15,498 preschool students. For universal SEL interventions delivered to all students, a random-effects model with 33 primary studies showed small to medium effects for the overall development of social and emotional skills (Hedges’s g = .34) and for the reduction of problem behaviors (g = .32), with an overall grand mean of g = .35. For targeted interventions, delivered to at-risk students identified as being in need of additional supports, a random-effects model with 15 primary studies showed medium effects for the overall development of social and emotional skills (Hedges’s g = .44) and for the reduction of problem behaviors (g = .50), with an overall grand mean of g = .48. A meta-regression model showed that intervention program accounted for 83% of heterogeneity in the overall effect size for universal interventions. Overall, this meta-analysis demonstrated that preschool children benefit from SEL interventions in different contexts, particularly those who were identified as being in need of early intervention. Moreover, best practices for preschool SEL interventions may differ from best practices for K–12 students, given the developmental uniqueness of the preschool years.

The OSIRIS‐REx target asteroid (101955) Bennu: Constraints on its physical, geological, and dynamical nature from astronomical observations
D. S. Lauretta, A. Bartels, Maria Antonella Barucci, E. B. Bierhaus +4 more
2014· Meteoritics and Planetary Science206doi:10.1111/maps.12353

Abstract We review the results of an extensive campaign to determine the physical, geological, and dynamical properties of asteroid (101955) Bennu. This investigation provides information on the orbit, shape, mass, rotation state, radar response, photometric, spectroscopic, thermal, regolith, and environmental properties of Bennu. We combine these data with cosmochemical and dynamical models to develop a hypothetical timeline for Bennu's formation and evolution. We infer that Bennu is an ancient object that has witnessed over 4.5 Gyr of solar system history. Its chemistry and mineralogy were established within the first 10 Myr of the solar system. It likely originated as a discrete asteroid in the inner Main Belt approximately 0.7–2 Gyr ago as a fragment from the catastrophic disruption of a large (approximately 100‐km), carbonaceous asteroid. It was delivered to near‐Earth space via a combination of Yarkovsky‐induced drift and interaction with giant‐planet resonances. During its journey, YORP processes and planetary close encounters modified Bennu's spin state, potentially reshaping and resurfacing the asteroid. We also review work on Bennu's future dynamical evolution and constrain its ultimate fate. It is one of the most Potentially Hazardous Asteroids with an approximately 1‐in‐2700 chance of impacting the Earth in the late 22nd century. It will most likely end its dynamical life by falling into the Sun. The highest probability for a planetary impact is with Venus, followed by the Earth. There is a chance that Bennu will be ejected from the inner solar system after a close encounter with Jupiter. OSIRIS‐REx will return samples from the surface of this intriguing asteroid in September 2023.

Physical, cognitive, social and mental health in near-centenarians and centenarians living in New York City: findings from the Fordham Centenarian Study
Daniela S. Jopp, Min-Kyung S. Park, Jonathan Lehrfeld, Michelle E. Paggi
2016· BMC Geriatrics202doi:10.1186/s12877-015-0167-0

BACKGROUND: Despite their strong increase, the population of the very old, including near-centenarians and centenarians, represent an unstudied and underserved population. Available studies mostly concentrate on predictors of exceptional longevity, but rarely extend their focus to other areas of functioning. Also, little is known about what contributes to experiencing a quality life in very old age. The present population-based study aims at providing a comprehensive picture of key domain of functioning, including physical, cognitive, social and mental function in very old individuals and to determine predictors of mental health indicators. METHODS: A total of 119 individuals aged 95 to 107 living in private dwellings and residential care facilities were recruited based on the New York City Voters Registry. Participants answered questions regarding their health and activities of daily living. Their cognitive functioning was determined using the Mini-Mental State Examination and the Global Deterioration Scale. Social resources were measured with number of children and the Lubben Scale. Mental health was assessed with the Geriatric Depression Scale and the Satisfaction with Life Scale. RESULTS: An unexpectedly large proportion of the sample lived in the community. On average, cognitive functioning was high. Although five diseases were reported on average, participants reported good health. Functional status was reduced. Most participants had at least one person for communication/social support. On average, depression was below cut-off, and most participants reported high life satisfaction. Regression analyses indicated that individual differences in depression were associated with subjective health, IADL and relatives support. For life satisfaction, subjective health, ADL and number of children were most important. Demographic characteristics, number of illnesses or cognitive status were not significant. CONCLUSIONS: Despite reduced levels of physical functioning and social resources, very old participants were in good mental health suggesting high resilience and ability to adapt to age-associated challenges. That a large proportion of them lived in the community further highlights their desire for leading an autonomous life, which may have been facilitated by New York service culture. More research is necessary to provide guidance for the development of well-suited services for this very old population.

Fatty Acid-binding Proteins Transport N-Acylethanolamines to Nuclear Receptors and Are Targets of Endocannabinoid Transport Inhibitors
Martin Kaczocha, Stephanie Vivieca, Jing Sun, Sherrye T. Glaser +1 more
2011· Journal of Biological Chemistry191doi:10.1074/jbc.m111.304907

N-acylethanolamines (NAEs) are bioactive lipids that engage diverse receptor systems. Recently, we identified fatty acid-binding proteins (FABPs) as intracellular NAE carriers. Here, we provide two new functions for FABPs in NAE signaling. We demonstrate that FABPs mediate the nuclear translocation of the NAE oleoylethanolamide, an agonist of nuclear peroxisome proliferator-activated receptor α (PPARα). Antagonism of FABP function through chemical inhibition, dominant-negative approaches, or shRNA-mediated knockdown reduced PPARα activation, confirming a requisite role for FABPs in this process. In addition, we show that NAE analogs, traditionally employed as inhibitors of the putative endocannabinoid transmembrane transporter, target FABPs. Support for the existence of the putative membrane transporter stems primarily from pharmacological inhibition of endocannabinoid uptake by such transport inhibitors, which are widely employed in endocannabinoid research despite lacking a known cellular target(s). Our approach adapted FABP-mediated PPARα signaling and employed in vitro binding, arachidonoyl-[1-(14)C]ethanolamide ([(14)C]AEA) uptake, and FABP knockdown to demonstrate that transport inhibitors exert their effects through inhibition of FABPs, thereby providing a molecular rationale for the underlying physiological effects of these compounds. Identification of FABPs as targets of transport inhibitors undermines the central pharmacological support for the existence of an endocannabinoid transmembrane transporter.

Modal mineralogy of CI and CI-like chondrites by X-ray diffraction
A. J. King, P. F. Schofield, K. T. Howard, S. S. Russell
2015· Geochimica et Cosmochimica Acta182doi:10.1016/j.gca.2015.05.038

The CI chondrites are some of the most hydrated meteorites available to study, making them ideal samples with which to investigate aqueous processes in the early Solar System. Here, we have used position-sensitive-detector X-ray diffraction (PSD-XRD) to quantify the abundance of minerals in bulk samples of the CI chondrite falls Alais, Orgueil and Ivuna, and the Antarctic CI-like chondrites Y-82162 and Y-980115. We find that Alais, Orgueil and Ivuna are dominated by a mixed serpentine/saponite phyllosilicate (81–84 vol%), plus minor magnetite (6–10%), sulphides (4–7%) and carbonates (3%). This reflects an extended period of aqueous alteration and the near-complete transformation of anhydrous phases into a secondary mineral assemblage. The similarity in total abundance of phyllosilicate suggests that the CI chondrites all experienced the same degree of aqueous alteration on the parent body.
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\nIn contrast, Y-82162 contains a highly disordered serpentine/saponite phyllosilicate (68 vol%), sulphide (19%), olivine (11%) and magnetite (2%). This mineralogy is distinct from that of the CI chondrites, attesting to both a different starting mineralogy and alteration history. The structure and relatively low abundance of the phyllosilicate, and the high abundance of olivine, are consistent with previous observations that Y-82162 represents CI-like material that following aqueous alteration suffered thermal metamorphism at temperatures 500 °C. Similarly, Y-980115 contains disordered serpentine/saponite (71 vol%), sulphide (19%), olivine (8%) and magnetite (2%), confirming that it too is a thermally metamorphosed CI-like chondrite. We suggest that the CI-like chondrites are derived from a different parent body than the CI chondrites, which underwent short-lived thermal metamorphism due to impacts and/or solar radiation.

Centennial changes in North Pacific anoxia linked to tropical trade winds
Curtis Deutsch, William M. Berelson, Robert C. Thunell, Thomas Weber +4 more
2014· Science179doi:10.1126/science.1252332

Climate warming is expected to reduce oxygen (O2) supply to the ocean and expand its oxygen minimum zones (OMZs). We reconstructed variations in the extent of North Pacific anoxia since 1850 using a geochemical proxy for denitrification (δ(15)N) from multiple sediment cores. Increasing δ(15)N since ~1990 records an expansion of anoxia, consistent with observed O2 trends. However, this was preceded by a longer declining δ(15)N trend that implies that the anoxic zone was shrinking for most of the 20th century. Both periods can be explained by changes in winds over the tropical Pacific that drive upwelling, biological productivity, and O2 demand within the OMZ. If equatorial Pacific winds resume their predicted weakening trend, the ocean's largest anoxic zone will contract despite a global O2 decline.

A cross-sectional study of well water arsenic and child IQ in Maine schoolchildren
Gail A. Wasserman, Xinhua Liu, Nancy J. LoIacono, Jennie Kline +4 more
2014· Environmental Health179doi:10.1186/1476-069x-13-23

BACKGROUND: In recent studies in Bangladesh and elsewhere, exposure to arsenic (As) via drinking water is negatively associated with performance-related aspects of child intelligence (e.g., Perceptual Reasoning, Working Memory) after adjustment for social factors. Because findings are not easily generalizable to the US, we examine this relation in a US population. METHODS: In 272 children in grades 3-5 from three Maine school districts, we examine associations between drinking water As (WAs) and intelligence (WISC-IV). RESULTS: On average, children had resided in their current home for 7.3 years (approximately 75% of their lives). In unadjusted analyses, household well WAs is associated with decreased scores on most WISC-IV Indices. With adjustment for maternal IQ and education, HOME environment, school district and number of siblings, WAs remains significantly negatively associated with Full Scale IQ and Perceptual Reasoning, Working Memory and Verbal Comprehension scores. Compared to those with WAs < 5 μg/L, exposure to WAs ≥ 5 μg/L was associated with reductions of approximately 5-6 points in both Full Scale IQ (p < 0.01) and most Index scores (Perceptual Reasoning, Working Memory, Verbal Comprehension, all p's < 0.05). Both maternal IQ and education were associated with lower levels of WAs, possibly reflecting behaviors (e.g., water filters, residential choice) limiting exposure. Both WAs and maternal measures were associated with school district. CONCLUSIONS: The magnitude of the association between WAs and child IQ raises the possibility that levels of WAs ≥ 5 μg/L, levels that are not uncommon in the United States, pose a threat to child development.

Why Are Gender Quotas Adopted? Party Pragmatism and Parity in France
Rainbow Murray, Mona Lena Krook, Katherine A.R. Opello
2011· Political Research Quarterly177doi:10.1177/1065912911414590

The passage of electoral gender quotas raises questions about why male elites would support policies that seemingly go against their self-interests. Recent work on France suggests that quota adoption is self-interested because male legislators benefit from alleged voter bias against female candidates. This article evaluates this explanation as a means for understanding quota adoption globally. It argues that the key actors are not legislators but political parties. Developing an alternative causal story centered on “party pragmatism,” it finds that decisions to introduce quotas are rational and consistent once a range of incentives—ideological, electoral, and strategic—are taken into account.

An analysis of the concept ‘patient satisfaction’ as it relates to contemporary nursing care
Pamela Young Mahon
1996· Journal of Advanced Nursing171doi:10.1111/j.1365-2648.1996.tb01031.x

Patient satisfaction has become an established indicator of the quality of health care yet, despite the abundance of measurement surveys reported in the literature, there are few theoretical underpinnings for this important concept. An analysis of the concept of patient satisfaction, specifically as it relates to contemporary nursing care, provides an excellent vantage point to more closely examine this key measure of health care quality. A review of pertinent literature is presented, followed by examination of the uses of the concept in professional literature as well as more general sources. Defining attributes cited throughout the literature are identified along with the concept's antecedents and consequences. Empirical referents, definitions, and measurements are also presented. The analysis concludes with re-examination of some of the assumptions underlying patient satisfaction literature in general, and thoughts regarding the significance of patient satisfaction with nursing care in particular. Suggestions for future inquiry are offered.

Chagas disease in the 21st Century: a public health success or an emerging threat?
Kevin M. Bonney
2014· Parasite169doi:10.1051/parasite/2014012

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, is a major public health burden in Latin America and a potentially serious emerging threat to a number of countries throughout the world. Although public health programs have significantly reduced the prevalence of Chagas disease in Latin America in recent decades, the number of infections in the United States and non-endemic countries in Europe and the Western Pacific Region continues to rise. Moreover, there is still no vaccine or highly effective cure available for the approximately 10 million people currently infected with T. cruzi, a third of which will develop potentially fatal cardiomyopathy and/or severe digestive tract disorders. As Chagas disease becomes an increasingly globalized public health issue in the twenty-first century, continued attentiveness from governmental and health organizations as well as improved diagnostic tools, expanded surveillance and increased research funding will be required to maintain existing public health successes and stymie the spread of the disease to new areas and populations.

A new metal‐rich chondrite grouplet
M. K. Weisberg, M. Prinz, Robert N. Clayton, T. K. Mayeda +3 more
2001· Meteoritics and Planetary Science164doi:10.1111/j.1945-5100.2001.tb01882.x

Abstract— A new grouplet of primitive, metal‐rich chondrites, here called the CB (C, carbonaceous; B, bencubbinite) chondrites, has been recognized. It includes Bencubbin, Weatherford, Hammadah al Hamra (HH) 237 and Queen Alexandra Range (QUE) 94411, paired with QUE 94627. Their mineral compositions, as well as their oxygen and nitrogen isotopic compositions, indicate that they are closely related to the CR and CH chondrites, all of which are members of the more inclusive CR clan. CB chondrites have much greater metal/silicate ratios than any other chondrite group, widely increasing the range of metal/silicate fractionation recorded in solar nebular processes. They also have the greatest moderately volatile lithophile element depletions of any chondritic materials. Metal has compositional trends and zoning patterns that suggest a primitive condensation origin, in contrast with metal from other chondrite groups. CB chondrites, as well as other CR clan chondrites, have much heavier nitrogen (higher 15 N/ 14 N) than that in other chondrite groups. The primitive characteristics of the CB chondrites suggest that they contain one of the best records of early nebular processes. Another chondrite, Grosvenor Mountains 95551, is petrographically similar to the CB chondrites, but its mineral and oxygen and nitrogen isotope compositions indicate that it formed from a different nebular reservoir.

Comparing Wild 2 particles to chondrites and IDPs
M. E. Zolensky, K. Nakamura‐Messenger, Frans J. M. Rietmeijer, Hugues Leroux +4 more
2008· Meteoritics and Planetary Science152doi:10.1111/j.1945-5100.2008.tb00621.x

Abstract— We compare the observed composition ranges of olivine, pyroxene, and Fe‐Ni sulfides in Wild 2 grains with those from chondritic interplanetary dust particles (IDPs) and chondrite classes to explore whether these data suggest affinities to known hydrous materials in particular. Wild 2 olivine has an extremely wide composition range, from Fa 0–96 , with a pronounced frequency peak at Fa 1 . The composition range displayed by the low‐calcium pyroxene is also very extensive, from Fs 48 to Fs 0 , with a significant frequency peak centered at Fs 5 . These ranges are as broad or broader than those reported for any other extraterrestrial material. Wild 2 Fe‐Ni sulfides mainly have compositions close to that of FeS, with less than 2 atom% Ni; to date, only two pentlandite grains have been found among the Wild grains, suggesting that this mineral is not abundant. The complete lack of compositions between FeS and pentlandite (with intermediate solid solution compositions) suggests (but does not require) that FeS and pentlandite condensed as crystalline species, i.e., did not form as amorphous phases, which later became annealed. While we have not yet observed any direct evidence of water‐bearing minerals, the presence of Ni‐bearing sulfides, and magnesium‐dominated olivine and low‐Ca pyroxene does not rule out their presence at low abundance. We do conclude that new investigations of major‐ and minor‐ element compositions of chondrite matrix and IDPs are required.

The importance of experiments: Constraints on chondrule formation models
Steven J. Desch, Melissa A. MORRIS, H. C. Connolly, Alan P. Boss
2012· Meteoritics and Planetary Science150doi:10.1111/j.1945-5100.2012.01357.x

Abstract— We review a number of constraints that have been placed on the formation of chondrules and show how these can be used to test chondrule formation models. Four models in particular are examined: the “X‐wind” model (sudden exposure to sunlight &lt;0.1 AU from the proto‐Sun, with subsequent launching in a magnetocentrifugal outflow); solar nebula lightning; nebular shocks driven by eccentric planetesimals; and nebular shocks driven by diskwide gravitational instabilities. We show that constraints on the thermal histories of chondrules during their melting and crystallization are the most powerful constraints and provide the least ambiguous tests of the chondrule formation models. Such constraints strongly favor melting of chondrules in nebular shocks. Shocks driven by gravitational instabilities are somewhat favored over planetesimal bow shocks.

Carbonate abundances and isotopic compositions in chondrites
C. M. O'd. Alexander, R. Bowden, Marilyn L. Fogel, K. T. Howard
2015· Meteoritics and Planetary Science150doi:10.1111/maps.12410

Abstract We report the bulk C abundances, and C and O isotopic compositions of carbonates in 64 CM chondrites, 14 CR chondrites, 2 CI chondrites, LEW 85332 (C2), Kaba ( CV 3), and Semarkona ( LL 3.0). For the unheated CM s, the total ranges of carbonate isotopic compositions are δ 13 C ≈ 25–75‰ and δ 18 O ≈ 15–35‰, and bulk carbonate C contents range from 0.03 to 0.60 wt%. There is no simple correlation between carbonate abundance and isotopic composition, or between either of these parameters and the extent of alteration. Unless accretion was very heterogeneous, the uncorrelated variations in extent of alteration and carbonate abundance suggests that there was a period of open system behavior in the CM parent body, probably prior to or at the start of aqueous alteration. Most of the ranges in CM carbonate isotopic compositions can be explained by their formation at different temperatures (0–130 °C) from a single fluid in which the carbonate O isotopes were controlled by equilibrium with water (δ 18 O ≈ 5‰) and the C isotopes were controlled by equilibrium with CO and/or CH 4 (δ 13 C ≈ −33‰ or −20‰ for CO ‐ or CH 4 ‐dominated systems, respectively). However, carbonate formation would have to have been inefficient, otherwise carbonate compositions would have resembled those of the starting fluid. A quite similar fluid composition (δ 18 O ≈ −5.5‰, and δ 13 C ≈ −31‰ or −17‰ for CO ‐ or CH 4 ‐dominated systems, respectively) can explain the carbonate compositions of the CI s, although the formation temperatures would have been lower (~10–40 °C) and the relative abundances of calcite and dolomite may play a more important role in determining bulk carbonate compositions than in the CM s. The CR carbonates exhibit a similar range of O isotopes, but an almost bimodal distribution of C isotopes between more (δ 13 C ≈ 65–80‰) and less altered samples (δ 13 C ≈ 30–40‰). This bimodality can still be explained by precipitation from fluids with the same isotopic composition (δ 18 O ≈ −9.25‰, and δ 13 C ≈ −21‰ or −8‰ for CO ‐ or CH 4 ‐dominated systems, respectively) if the less altered CR s had higher mole fractions of CO 2 in their fluids. Semarkona and Kaba carbonates have some of the lightest C isotopic compositions of the meteorites studied here, probably because they formed at higher temperatures and/or from more CO 2 ‐rich fluids. The fluids responsible for the alteration of chondrites and from which the carbonates formed were almost certainly accreted as ices. By analogy with cometary ices, CO 2 and/or CO would have dominated the trapped volatile species in the ices. The chondrites studied are too oxidized for CO ‐dominated fluids to have formed in their parent bodies. If CH 4 was the dominant C species in the fluids during carbonate formation, it would have to have been generated in the parent bodies from CO and/or CO 2 when oxidation of metal by water created high partial pressures of H 2 . The fact that the chondrite carbonate C/H 2 O mole ratios are of the order predicted for CO / CO 2 ‐H 2 O ices that experienced temperatures of &gt;50–100 K suggests that the chondrites formed at radial distances of &lt;4–15 AU.