1,989 research outputs found

    New Measurements of the Motion of the Zodiacal Dust

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    Using the Wisconsin H-Alpha Mapper (WHAM), we have measured at high spectral resolution and high signal-to-noise the profile of the scattered solar Mg I 5184 absorption line in the zodiacal light. The observations were carried out toward 49 directions that sampled the ecliptic equator from solar elongations of 48\dg (evening sky) to 334\dg (morning sky) plus observations near +47\dg and +90\dg ecliptic latitude. The spectra show a clear prograde kinematic signature that is inconsistent with dust confined to the ecliptic plane and in circular orbits influenced only by the sun's gravity. In particular, the broadened widths of the profiles, together with large amplitude variations in the centroid velocity with elongation angle, indicate that a significant population of dust is on eccentric orbits. In addition, the wide, flat-bottomed line profile toward the ecliptic pole indicates a broad distribution of orbital inclinations extending up to about 30\dg - 40\dg with respect to the ecliptic plane. The absence of pronounced asymmetries in the shape of the profiles limits the retrograde population to less than 10% of the prograde population and also places constraints on the scattering phase function of the particles. These results do not show the radial outflow or evening--morning velocity amplitude asymmetry reported in some earlier investigations. The reduction of the spectra included the discovery and removal of extremely faint, unidentified terrestrial emission lines that contaminate and distort the underlying Mg I profile. This atmospheric emission is too weak to have been seen in earlier, lower signal-to-noise observations, but it probably affected the line centroid measurements of previous investigations.Comment: 24 pages, 8 figures, 1 table, to appear in ApJ v612; figures appear low-res only on scree

    Nocturnal thoracoabdominal asynchrony in house dust mite-sensitive nonhuman primates

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    Nocturnal bronchoconstriction is a common symptom of asthma in humans, but is poorly documented in animal models. Thoracoabdominal asynchrony (TAA) is a noninvasive clinical indication of airway obstruction. In this study, respiratory inductive plethysmography (RIP) was used to document nocturnal TAA in house dust mite (HDM)-sensitive Cynomolgus macaques. Dynamic compliance (Cdyn) and lung resistance (RL) measured in anesthetized animals at rest and following exposure to HDM allergen, methacholine, and albuterol were highly correlated with three RIP parameters associated with TAA, ie, phase angle of the rib cage and abdomen waveforms (PhAng), baseline effort phase relation (eBPRL) and effort phase relation (ePhRL). Twenty-one allergic subjects were challenged with HDM early in the morning, and eBPRL and ePhRL were monitored for 20 hours after provocation. Fifteen of the allergic subjects exhibited gradual increases in eBPRL and ePhRL between midnight and 6 am, with peak activity at 4 am. However, as in humans, this nocturnal response was highly variable both between subjects and within subjects over time. The results document that TAA in this nonhuman primate model of asthma is highly correlated with Cdyn and RL, and demonstrate that animals exhibiting acute responses to allergen exposure during the day also exhibit nocturnal TAA

    The First Detections of the Extragalactic Background Light at 3000, 5500, and 8000A (II): Measurement of Foreground Zodiacal Light

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    We present a measurement of the absolute surface brightness of the zodiacal light (3900-5100A) toward a fixed extragalactic target at high ecliptic latitude based on moderate resolution (~1.3A per pixel) spectrophotometry obtained with the du Pont 2.5m telescope at Las Campanas Observatory in Chile. This measurement and contemporaneous Hubble Space Telescope data from WFPC2 and FOS comprise a coordinated program to measure the mean flux of the diffuse extragalactic background light (EBL). The zodiacal light at optical wavelengths results from scattering by interplanetary dust, so that the zodiacal light flux toward any extragalactic target varies seasonally with the position of the Earth. This measurement of zodiacal light is therefore relevant to the specific observations (date and target field) under discussion. To obtain this result, we have developed a technique that uses the strength of the zodiacal Fraunhofer lines to identify the absolute flux of the zodiacal light in the multiple-component night sky spectrum. Statistical uncertainties in the result are 0.6% (1 sigma). However, the dominant source of uncertainty is systematic errors, which we estimate to be 1.1% (1 sigma). We discuss the contributions included in this estimate explicitly. The systematic errors in this result contribute 25% in quadrature to the final error in our coordinated EBL measurement, which is presented in the first paper of this series.Comment: Accepted for publication in ApJ, 22 pages using emulateapj.sty, version with higher resolution figures available at http://www.astro.lsa.umich.edu/~rab/publications.html or at http://nedwww.ipac.caltech.edu/level5/Sep01/Bernstein2/frames.htm

    N6-methyladenosine contributes to cellular phenotype in a genetically-defined model of breast cancer progression

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    The mRNA modification N6-methyladenosine (m6A) is involved in many post- transcriptional regulatory processes including mRNA stability and translational efficiency. However, it is also imperative to correlate these processes with phenotypic outputs during cancer progression. Here we report that m6A levels are significantly decreased in genetically-defined immortalized and oncogenically-transformed human mammary epithelial cells (HMECs), as compared with their primary cell predecessor. Furthermore, the m6A methyltransferase (METTL3) is decreased and the demethylase (ALKBH5) is increased in the immortalized and transformed cell lines, providing a possible mechanism for this basal change in m6A levels. Although the immortalized and transformed cells showed lower m6A levels than their primary parental cell line, overexpression of METTL3 and METTL14, or ALKBH5 knockdown to increase m6A levels in transformed cells increased proliferation and migration. Remarkably, these treatments had little effect on the immortalized cells. Together, these results suggest that m6A modification may be downregulated in immortalized cells as a brake against malignant progression. Finally, we found that m6A levels in the immortalized and transformed cells increased in response to hypoxia without corresponding changes in METTL3, METTL14 or ALKBH5 expression, suggesting a novel pathway for regulation of m6A levels under stress

    Sensitive Periods for Psychosocial Risk in Childhood and Adolescence and Cardiometabolic Outcomes in Young Adulthood

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    Greater psychosocial risk in childhood and adolescence predicts poorer cardiometabolic outcomes in adulthood. We assessed whether the timing of psychosocial risk from infancy through adolescence predicts cardiometabolic outcomes in young adulthood. Young adults and their mothers participated in a longitudinal study beginning in infancy in Santiago, Chile (N = 1040). At infancy, 5 years, 10 years, and adolescence, mothers reported on depressive symptoms, stressful experiences, support for child development in the home, father absence, parental education, and socioeconomic status (SES) to create a psychosocial risk composite at each time point. Young adults (52.1% female; 21–27 years) provided fasting serum samples and participated in anthropometric and blood pressure (BP) assessments, including a dualenergy X-ray absorptiometry (DXA) scan for measuring body fat. Greater infant psychosocial risk was associated with a greater young adult metabolic syndrome score (β = 0.07, 95% confidence intervals (CI): 0.01 to 0.13, p = 0.02), a higher body mass index and waist circumference composite (β = 0.08, 95% CI: 0.03 to 0.13, p = 0.002), and a higher body fat (DXA) composite (β = 0.07, 95% CI: 0.01 to 0.12, p = 0.02). No psychosocial risk measure from any time point was associated with BP. Infant psychosocial risk predicted cardiometabolic outcomes in young adulthood better than psychosocial risk at 5 years, 10 years, or adolescence, mean of psychosocial risk from infancy through adolescence, and maximum of psychosocial risk at any one time. Consistent with the Developmental Origins of Health and Disease model, findings suggest that infancy is a sensitive period for psychosocial risk leading to poorer cardiometabolic outcomes in young adulthood

    Preparedness of Australian and British nurses and midwives about domestic violence and abuse

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    BACKGROUND: Domestic violence and abuse (DVA) is a major health problem that affects individuals across the world. Nurses, midwives and healthcare providers need to be confident and competent in identifying and responding to DVA. AIMS: To measure current levels of knowledge, opinions and preparedness towards DVA and how it is managed by registered nurses and midwives residing in Australia and the UK. METHODS: A cross-sectional study design was used. Data were collected using the Physician Readiness to Manage Intimate Partner Violence Survey (PREMIS) measuring the perceived preparation and knowledge, actual knowledge, opinions and practice issues. Australian data were collected in 2018 and UK data were collected in 2017-2018. Descriptive and inferential statistics were used to analyse the data and differences in knowledge and attitudes of British and Australian nurses. FINDINGS: Nurses and midwives (n = 368; 130 from Australia; 238 from the UK) responded to the survey. Minimal previous DVA training was reported by the participants. Participants had minimal knowledge about DVA, though had a positive attitude towards engaging with women experiencing DVA. DISCUSSION: Most participants felt unprepared to ask relevant questions about DVA and had inadequate knowledge about available resources. Australian participants scored better than British participants; however, the mean difference in all aspects remained statistically insignificant. CONCLUSION: Australian and British nurses and midwives have a positive attitude towards women experiencing DVA; however, the knowledge and skills to support women experiencing DVA are limited. IMPLICATIONS FOR NURSING POLICY: Nursing institutions should develop strategic policies regarding mandatory preparation and training of nurses for domestic violence assessment and management

    Measured g factors and the tidal-wave description of transitional nuclei near A = 100

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    The transient-field technique has been used in both conventional kinematics and inverse kinematics to measure the g factors of the 2+ states in the stable even isotopes of Ru, Pd and Cd. The statistical precision of the g(2+) values has been significantly improved, allowing a critical comparison with the tidal-wave version of the cranking model recently proposed for transitional nuclei in this region.Comment: Accepted for publication in Physical Review C, April 201

    The Chicken Yolk Sac IgY Receptor, a Mammalian Mannose Receptor Family Member, Transcytoses IgY across Polarized Epithelial Cells

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    In mammals the transfer of passive immunity from mother to young is mediated by the MHC-related receptor FcRn, which transports maternal IgG across epithelial cell barriers. In birds, maternal IgY in egg yolk is transferred across the yolk sac to passively immunize chicks during gestation and early independent life. The chicken yolk sac IgY receptor (FcRY) is the ortholog of the mammalian phospholipase A2 receptor, a mannose receptor family member, rather than an FcRn or MHC homolog. FcRn and FcRY both exhibit ligand binding at the acidic pH of endosomes and ligand release at the slightly basic pH of blood. Here we show that FcRY expressed in polarized mammalian epithelial cells functioned in endocytosis, bidirectional transcytosis, and recycling of chicken FcY/IgY. Confocal immunofluorescence studies demonstrated that IgY binding and endocytosis occurred at acidic but not basic pH, mimicking pH-dependent uptake of IgG by FcRn. Colocalization studies showed FcRY-mediated internalization via clathrin-coated pits and transport involving early and recycling endosomes. Disruption of microtubules partially inhibited apical-to-basolateral and basolateral-to-apical transcytosis, but not recycling, suggesting the use of different trafficking machinery. Our results represent the first cell biological evidence of functional equivalence between FcRY and FcRn and provide an intriguing example of how evolution can give rise to systems in which similar biological requirements in different species are satisfied utilizing distinct protein folds

    InGaAs/InP hot electron transistors grown by chemical beam epitaxy

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    In this letter, we report on the dc performance of chemical beam epitaxy grown InGaAs/InP hot electron transistors (HETs). The highest observed differential β (dIC/dIB) is over 100. The HETs have Pd/Ge/Ti/Al shallow ohmic base contacts with diffusion lengths less than 300 Å. Furthermore, we also demonstrated ballistic transport of electrons in an InGaAs/InP HET by obtaining an energy distribution of electrons with ∼60 meV full width at half maximum. The measured conduction band discontinuity of InGaAs/InP is 250.3 meV, which is 39.8% of the band gap difference.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70748/2/APPLAB-61-2-189-1.pd

    Short-term, high-fat diet accelerates disuse atrophy and protein degradation in a muscle-specific manner in mice

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    Background: A short-term high-fat diet impairs mitochondrial function and the ability of skeletal muscle to respond to growth stimuli, but it is unknown whether such a diet alters the ability to respond to atrophy signals. The purpose of this study was to determine whether rapid weigh gain induced by a high-fat (HF) diet accelerates denervation-induced muscle atrophy. Methods: Adult, male mice (C57BL/6) were fed a control or HF (60 % calories as fat) diet for 3 weeks (3wHF). Sciatic nerve was sectioned unilaterally for the final 5 or 14 days of the diet. Soleus and extensor digitorum longus (EDL) muscles were removed and incubated in vitro to determine rates of protein degradation and subsequently homogenized for determination of protein levels of LC3, ubiquitination, myosin heavy chain (MHC) distribution, and mitochondrial subunits. Results: When mice were fed the 3wHF diet, whole-body fat mass more than doubled, but basal (innervated) muscle weights, rates of protein degradation, LC3 content, mitochondrial protein content, and myosin isoform distribution were not significantly different than with the control diet in either soleus or EDL. However in the 14 day denervated soleus, the 3wHF diet significantly augmented loss of mass, proteolysis rate, amount of the autophagosome marker LC3 II, and the amount of overall ubiquitination as compared to the control fed mice. On the contrary, the 3wHF diet had no significant effect in the EDL on amount of mass loss, proteolysis rate, LC3 levels, or ubiquitination. Fourteen days denervation also induced a loss of mitochondrial proteins in the soleus but not the EDL, regardless of the diet. Conclusions: Taken together, a short-term, high-fat diet augments denervation muscle atrophy by induction of protein degradation in the mitochondria-rich soleus but not in the glycolytic EDL. These findings suggest that the denervation-induced loss of mitochondria and HF diet-induced impairment of mitochondrial function may combine to promote skeletal muscle atrophy
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