Co-movement of astral microtubules, organelles and F-actin by dynein and actomyosin forces in frog egg cytoplasm

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Pelletier, J. F., Field, C. M., Furthauer, S., Sonnett, M., & Mitchison, T. J. Co-movement of astral microtubules, organelles and F-actin by dynein and actomyosin forces in frog egg cytoplasm. Elife, 9, (2020): e60047, https://doi.org/10.7554/eLife.60047.How bulk cytoplasm generates forces to separate post-anaphase microtubule (MT) asters in Xenopus laevis and other large eggs remains unclear. Previous models proposed that dynein-based, inward organelle transport generates length-dependent pulling forces that move centrosomes and MTs outwards, while other components of cytoplasm are static. We imaged aster movement by dynein and actomyosin forces in Xenopus egg extracts and observed outward co-movement of MTs, endoplasmic reticulum (ER), mitochondria, acidic organelles, F-actin, keratin, and soluble fluorescein. Organelles exhibited a burst of dynein-dependent inward movement at the growing aster periphery, then mostly halted inside the aster, while dynein-coated beads moved to the aster center at a constant rate, suggesting organelle movement is limited by brake proteins or other sources of drag. These observations call for new models in which all components of the cytoplasm comprise a mechanically integrated aster gel that moves collectively in response to dynein and actomyosin forces.This work was supported by NIH grant R35GM131753 (TJM) and MBL fellowships from the Evans Foundation, MBL Associates, and the Colwin Fund (TJM and CMF). JFP was supported by the Fannie and John Hertz Foundation, the Fakhri lab at MIT, the MIT Department of Physics, and the MIT Center for Bits and Atoms

Implicit Review Instrument to Evaluate Quality of Care Delivered by Physicians to Children in Emergency Departments

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144238/1/hesr12800_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144238/2/hesr12800.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144238/3/hesr12800-sup-0001-AppendixSA1.pd

Spitzer/IRAC Photometry of M, L, and T Dwarfs

We present the results of a program to acquire photometry for eighty-six late-M, L, and T dwarfs using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We examine the behavior of these cool dwarfs in various color-color and color-magnitude diagrams composed of near-IR and IRAC data. The T dwarfs exhibit the most distinctive positions in these diagrams. In M_5.8 versus [5.8]-[8.0], the IRAC data for T dwarfs are not monotonic in either magnitude or color, giving the clearest indication yet that the T dwarfs are not a one parameter family in Teff. Because metallicity does not vary enough in the solar neighborhood to act as the second parameter, the most likely candidate then is gravity, which in turn translates to mass. Among objects with similar spectral type, the range of mass suggested by our sample is about a factor of five (~70 M_Jup to ~15 M_Jup), with the less massive objects making up the younger members of the sample. We also find the IRAC 4.5 micron fluxes to be lower than expected, from which we infer a stronger CO fundamental band at ~4.67 microns. This suggests that equilibrium CH_4/CO chemistry underestimates the abundance of CO in T dwarf atmospheres, confirming earlier results based on M-band observations from the ground. In combining IRAC photometry with near-IR JHK photometry and parallax data, we find the combination of Ks, IRAC 3.6 micron, and 4.5 micron bands to provide the best color-color discrimination for a wide range of M, L, and T dwarfs. Also noteworthy is the M_Ks versus Ks-[4.5] relation, which shows a smooth progression over spectral type and splits the M, L, and T types cleanly.Comment: 32 pages, 18 figures, accepted for publication to ApJ: revised to adjust acknowledgments, add a few more references, and the correct typographical errors in text and tables 1 and 3 (note as binaries sds0926+5847 and 2ma1553+1532

Patientâ level Factors and the Quality of Care Delivered in Pediatric Emergency Departments

ObjectiveQuality of care delivered to adult patients in the emergency department (ED) is often associated with demographic and clinical factors such as a patient’s race/ethnicity and insurance status. We sought to determine whether the quality of care delivered to children in the ED was associated with a variety of patientâ level factors.MethodsThis was a retrospective, observational cohort study. Pediatric patients (<18 years) who received care between January 2011 and December 2011 at one of 12 EDs participating in the Pediatric Emergency Care Applied Research Network (PECARN) were included. We analyzed demographic factors (including age, sex, and payment source) and clinical factors (including triage, chief complaint, and severity of illness). We measured quality of care using a previously validated implicit review instrument using chart review with a summary score that ranged from 5 to 35. We examined associations between demographic and clinical factors and quality of care using a hierarchical multivariable linear regression model with hospital site as a random effect.ResultsIn the multivariable model, among the 620 ED encounters reviewed, we did not find any association between patient age, sex, race/ethnicity, and payment source and the quality of care delivered. However, we did find that some chief complaint categories were significantly associated with lower than average quality of care, including fever (â 0.65 points in quality, 95% confidence interval [CI] = â 1.24 to â 0.06) and upper respiratory symptoms (â 0.68 points in quality, 95% CI = â 1.30 to â 0.07).ConclusionWe found that quality of ED care delivered to children among a cohort of 12 EDs participating in the PECARN was high and did not differ by patient age, sex, race/ethnicity, and payment source, but did vary by the presenting chief complaint.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142981/1/acem13347_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142981/2/acem13347-sup-0001-DataSupplementS1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142981/3/acem13347.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142981/4/acem13347-sup-0002-DataSupplementS2.pd

The NEOWISE-Discovered Comet Population and the CO+CO_2 production rates

The 163 comets observed during the WISE/NEOWISE prime mission represent the largest infrared survey to date of comets, providing constraints on dust, nucleus size, and CO + CO_2 production. We present detailed analyses of the WISE/NEOWISE comet discoveries, and discuss observations of the active comets showing 4.6 μm band excess. We find a possible relation between dust and CO + CO_2 production, as well as possible differences in the sizes of long and short period comet nuclei

The cause and cure of speech disorders: a text book for students and teachers on stuttering, stammering and voice conditions,

Mode of access: Internet

Constraining the shape distribution and binary fractions of asteroids observed by NEOWISE

International audienceKnowing the shape distribution of an asteroid population gives clues to its collisional and dynamical history. Constraining light curve amplitudes (brightness variations) offers a first-order approximation to the shape distribution, provided all asteroids in the distribution were subject to the same observing biases. Asteroids observed by the NEOWISE space mission at roughly the same heliocentric distances have essentially the same observing biases and can therefore be inter-compared. We used the archival NEOWISE photometry of a statistically significant sample of Jovian Trojans, Hildas, and Main belt asteroids to compare the amplitude (and by proxy, shape) distributions of L4 vs. L5 Trojans, Trojans vs. Hildas of the same size range, and several subpopulations of Main belt asteroids.For asteroids with near-fluid rubble pile structures, very large light curve amplitudes can only be explained by close or contact binary systems, offering the potential to catalog and characterize binaries within a population and gleaning more information on its dynamical evolution. Because the structure of most asteroids is not known to a high confidence level, objects with very high light curve amplitudes can only be considered candidate binaries. In Sonnett et al. (2015), we identified several binary candidates in the Jovian Trojan and Hilda populations. We have since been conducting a follow-up campaign to obtain densely sampled light curves of the binary candidates to allow detailed shape and binary modeling, helping identify true binaries. Here, we present preliminary results from the follow-up campaign, including rotation properties.This research was carried out at the Jet Propulsion Laboratory (JPL), California Institute of Technology (CalTech) under a contract with the National Aeronautics and Space Administration (NASA) and was supported by the NASA Postdoctoral Program at JPL. We make use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and JPL/CalTech, funded by NASA. This publication also makes use of data products from NEOWISE, which is a project of JPL/CalTech, funded by the Planetary Science Division of NASA