2,214 research outputs found
Limits on Clouds and Hazes for the TRAPPIST-1 Planets
The TRAPPIST-1 planetary system is an excellent candidate for study of the
evolution and habitability of M-dwarf planets. Transmission spectroscopy
observations performed with the Hubble Space Telescope (HST) suggest the
innermost five planets do not possess clear hydrogen atmospheres. Here we
reassess these conclusions with recently updated mass constraints and expand
the analysis to include limits on metallicity, cloud top pressure, and the
strength of haze scattering. We connect recent laboratory results of particle
size and production rate for exoplanet hazes to a one-dimensional atmospheric
model for TRAPPIST-1 transmission spectra. Doing so, we obtain a
physically-based estimate of haze scattering cross sections. We find haze
scattering cross sections on the order of 1e-26 to 1e-19 cm squared are needed
in hydrogen-rich atmospheres for TRAPPIST-1 d, e, and f to match the HST data.
For TRAPPIST-1 g, we cannot rule out a clear hydrogen-rich atmosphere. We also
modeled the effects an opaque cloud deck and substantial heavy element content
have on the transmission spectra. We determine that hydrogen-rich atmospheres
with high altitude clouds, at pressures of 12mbar and lower, are consistent
with the HST observations for TRAPPIST-1 d and e. For TRAPPIST-1 f and g, we
cannot rule out clear hydrogen-rich cases to high confidence. We demonstrate
that metallicities of at least 60xsolar with tropospheric (0.1 bar) clouds
agree with observations. Additionally, we provide estimates of the precision
necessary for future observations to disentangle degeneracies in cloud top
pressure and metallicity. Our results suggest secondary, volatile-rich
atmospheres for the outer TRAPPIST-1 planets d, e, and f.Comment: 15 pages, 3 figures, 2 tables, accepted in the Astronomical Journa
Submaximal oxygen uptake efficiency slope as a predictor of VO2max in men with cardiovascular disease
Purpose: Although VĖO2 max is considered the gold standard measure of cardiorespiratory fitness (CRF), it can be difficult to attain in patients with cardiovascular disease (CVD). The submaximal oxygen uptake efficiency slope (OUES) integrates cardiovascular, musculoskeletal and respiratory function during incremental exercise into a single index and has been proposed as an alternative and effort independent measure of cardiopulmonary reserve (Baba et al., 1996). The purpose of this study was to examine the relation between VĖO2 max and both submaximal absolute OUES and relative OUES (OUES.kg-1).
Methods: A total of 55 men ((mean Âą SD) age, 59.08 Âą 9.03 yr; VO2 max, 1.94 Âą 0.53 L.min-1and 22.73 Âą 5.95 mL.kg-1.min-1) were recruited during induction to a community based exercise referral program following completion of phase 2 cardiac rehabilitation. Participants performed a graded exercise test on a cycle ergometer with breath-by-breath open circuit spirometry and a 12 lead ECG. Absolute OUES and OUES.kg-1 were calculated by plotting VO2 in mL.min-1 on the x-axis, and the log transformed VE on the y-axis (VO2 = a log 10 VE + b). Exercise data up to the ventilatory anaerobic threshold (VAT) was included in the analysis.
Results: The %VĖO2 max corresponding to the VAT was 55.72 Âą 11.81. Absolute OUES and OUES.kg-1 were 2164.42 Âą 540.96 and 25.28 Âą 5.99, respectively. There was a significant positive correlation between VĖO2 max (L.min-1) and OUES (r= 0.775; p<0.001) and between VĖO2 max (mL.kg-1.min-1) and OUES.kg-1 (r= 0.78; p<0.001).
Conclusion: Determination of VĖO2 max is not often feasible in individuals with CVD where maximal exercise testing is contraindicated or when performance may be impaired by pain, dyspnea or angina. The findings from the present study indicate that the OUES and OUES.kg-1 are significantly related to absolute and relative VĖO2 max, respectively and may be used as a valid sub maximal effort independent measure of CRF
Relation between physical activity and oxygen uptake efficiency in men with CVD
Purpose: The oxygen uptake efficiency slope (OUES) represents the rate of increase in VĖO2 in response to a given VĖE during incremental exercise, indicating how effectively oxygen is taken in by the lungs, transported and used in the periphery. OUES, calculated using only submaximal exercise data is identical to the OUES calculated over the entire duration of a cardiopulmonary exercise test (CEPT) , and both maximal and submaximal OUE are significantly related to cardiorespiratory fitness (CRF) measured as VĖO2peak. Currently, little research has been published on how physical activity (PA) assessed by accelerometers is related to submaximal and maximal OUES. The purpose of this study was to determine the relation light (LIPA), moderate (MIPA) and vigorous (VIPA) intensity physical activity and maximal and submaximal OUES in men with cardiovascular disease (CVD).
Methods: A total of 56 men (mean ( SD): age of 59.3 Âą 9.2 yr., VĖO2 peak (L/min) 2.0 0.50, VĖO2 peak (mL/kg/min) 23.6 5.8, were recruited during an induction to a community-based exercise referral program following completion of phase 2 cardiac rehabilitation program. Participants underwent a graded exercise test on a cycle ergometer with breath by breath open circuit spirometry after which they wore a wrist worn accelerometer (Actigraph) for 7 d. Absolute and relative submaximal and maximal OUES were calculated by plotting VĖO2 in mL/min on the x axis, and the log transformed VE on the y axis (VĖO2 = a log 10 VE + b). Exercise data up to the ventilatory anaerobic threshold and maximal exercise were used to calculate submaximal and maximal OUE, respectively.
Results: Participants performed 584.49 73.87 min of daily LIPA, 145.45 60.85 min of MIPA and no daily min of VIPA. There was a significant relation between absolute submaximal OUES (r=0.386; p<0.01), submaximal OUES/Kg (r=0.296; p<0.05) and LIPA. There was a significant relation between maximal OUES (r=0.286; p<0.05), maximal OUES/Kg (r=0.279; p<0.05) and MIPA.
Conclusion: Submaximal and maximal OUE are related to levels of LIPA and MIPA, respectively. Submaximal OUES can potentially be used as an objective, effort independent test to estimate LIPA levels among men with CVD
Physical activity patterns and cardiorespiratory fitness in men with cardiovascular disease
Purpose: Cardiorespiratory fitness (CRF) is generally regarded as an objective and reproducible measure of recent habitual physical activity (PA). Considering that the majority of daily PA is performed at light intensity, it is likely that CRF benefits will be detected at submaximal rather than maximal exercise. The purpose of this study was to evaluate daily minutes of light (LIPA), moderate (MIPA) and vigorous (VIPA) intensity physical activity among men with cardiovascular disease (CVD), and to determine the relation between PA and submaximal (oxygen uptake efficiency slope (OUES)) and maximal (VĖO2 peak) indices of CRF.
Methods: A total 32 male participants (mean ( SD): age of 60.0 Âą 8.7 yr, VĖO2 peak (L/min) 2.0 0.45, VĖO2 peak (mL/kg/min) 23.3 5.7, were recruited during an induction to a community based exercise referral program following completion of phase 2 cardiac rehabilitation. Participants underwent a graded exercise test on a cycle ergometer with breath by breath open circuit spirometry after which they wore a wrist worn accelerometer (Actigraph) for 7 d. Absolute and relative submaximal OUES were calculated by plotting VĖO2 in mL/min on the x axis, and the log transformed VE on the y axis (VĖO2 = a log 10 VE + b). Exercise data up to the ventilatory anaerobic threshold was included in the analysis.
Results: Participants performed 589.05 69.41 min of daily LIPA, 161.38 66.16 min of MIPA and no daily min of VIPA. There was no significant relation between peak VĖO2 and either LIPA or MIPA. There was a significant correlation between submaximal OUES (r=0.44; p<0.01) and LIPA. The relation between submaximal OUES/kg and LIPA min almost reached statistical significance (r=0.33; p<0.07). There was no significant relation between MIPA and OUES or OUES/kg.
Conclusion: Men with CVD spend the majority (78%) of their day performing LIPA. OUES, a submaximal measure of CRF was related LIPA whereas no relation was found between VĖO2 peak and LIPA
Cortisol patterns are associated with T cell activation in HIV.
ObjectiveThe level of T cell activation in untreated HIV disease is strongly and independently associated with risk of immunologic and clinical progression. The factors that influence the level of activation, however, are not fully defined. Since endogenous glucocorticoids are important in regulating inflammation, we sought to determine whether less optimal diurnal cortisol patterns are associated with greater T cell activation.MethodsWe studied 128 HIV-infected adults who were not on treatment and had a CD4(+) T cell count above 250 cells/Âĩl. We assessed T cell activation by CD38 expression using flow cytometry, and diurnal cortisol was assessed with salivary measurements.ResultsLower waking cortisol levels correlated with greater T cell immune activation, measured by CD38 mean fluorescent intensity, on CD4(+) T cells (r = -0.26, p = 0.006). Participants with lower waking cortisol also showed a trend toward greater activation on CD8(+) T cells (r = -0.17, p = 0.08). A greater diurnal decline in cortisol, usually considered a healthy pattern, correlated with less CD4(+) (r = 0.24, p = 0.018) and CD8(+) (r = 0.24, p = 0.017) activation.ConclusionsThese data suggest that the hypothalamic-pituitary-adrenal (HPA) axis contributes to the regulation of T cell activation in HIV. This may represent an important pathway through which psychological states and the HPA axis influence progression of HIV
Growth in a biofilm promotes conjugation of a bla <sub>NDM-1</sub>-bearing plasmid between <i>Klebsiella pneumoniae</i> strains
Optical Properties of Organic Haze Analogues in Water-rich Exoplanet Atmospheres Observable with JWST
JWST has begun its scientific mission, which includes the atmospheric
characterization of transiting exoplanets. Some of the first exoplanets to be
observed by JWST have equilibrium temperatures below 1000 K, which is a regime
where photochemical hazes are expected to form. The optical properties of these
hazes, which controls how they interact with light, are critical for
interpreting exoplanet observations, but relevant experimental data are not
available. Here we measure the density and optical properties of organic haze
analogues generated in water-rich exoplanet atmosphere experiments. We report
optical constants (0.4 to 28.6 {\mu}m) of organic haze analogues for current
and future observational and modeling efforts covering the entire wavelength
range of JWST instrumentation and a large part of Hubble. We use these optical
constants to generate hazy model atmospheric spectra. The synthetic spectra
show that differences in haze optical constants have a detectable effect on the
spectra, impacting our interpretation of exoplanet observations. This study
emphasizes the need to investigate the optical properties of hazes formed in
different exoplanet atmospheres, and establishes a practical procedure to
determine such properties.Comment: 4 figures, 1 Table, Published in Nature Astronom
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The sugar content of childrenâs and lunchbox beverages sold in the UK before and after the soft drink industry levy
Background: Childhood obesity is associated with an increased intake of sugary soft drinks and juice drinks. The aims of this study were (1) to report the sugar and energy content in commercial fruit juice (FJ), juice drinks (JD) and smoothies (S) specifically targeted at children in the UK, (2) to identify beverages liable for the Soft Drinks Industry Levy (SDIL) and (3) to compare the amount of sugar in these beverages before and after the levy.
Methods: The beverages were retrieved using the online shopping tool my Supermarket, websites of nine major supermarket in the UK and manufacturers webpages. Comparisons of sugar content were taken before and after the introduction of the SDIL.
Results: 131 FJJDS fulfilled the inclusion criteria. The mean sugar content of all the beverages was 6.3gÂą4.5/100mL. There was large variation in the sugar content from 0.1g/100mL to 15.2g/100mL, with smoothies found to contain the most sugar (11.55Âą1.62 g/mL). The beverages were reanalysed in September 2018 to determine their eligibility for the SDIL. Of the 131 products only 7 JD were eligible for the levy. Four of these beverages had reformulated their ingredients since the initial analysis resulting in a sugar content of <5g/100mL.
Conclusions: The majority of the beverages targeted at children and childrenâs lunch boxes were not eligible for the SDIL. This study suggests the necessity to adapt the SDIL to include all FJJDS aimed at children as the total sugar content of these beverages are still above the recommended quantities for this age group
Intensified and protective CD4+ T cell immunity in mice with antiâdendritic cell HIV gag fusion antibody vaccine
Current human immunodeficiency virus (HIV) vaccine approaches emphasize prime boost strategies comprising multiple doses of DNA vaccine and recombinant viral vectors. We are developing a protein-based approach that directly harnesses principles for generating T cell immunity. Vaccine is delivered to maturing dendritic cells in lymphoid tissue by engineering protein antigen into an antibody to DEC-205, a receptor for antigen presentation. Here we characterize the CD4+ T cell immune response to HIV gag and compare efficacy with other vaccine strategies in a single dose. DEC-205âtargeted HIV gag p24 or p41 induces stronger CD4+ T cell immunity relative to high doses of gag protein, HIV gag plasmid DNA, or recombinant adenovirus-gag. High frequencies of interferon (IFN)-Îģâ and interleukin 2âproducing CD4+ T cells are elicited, including double cytokine-producing cells. In addition, the response is broad because the primed mice respond to an array of peptides in different major histocompatibility complex haplotypes. Long-lived T cell memory is observed. After subcutaneous vaccination, CD4+ and IFN-Îģâdependent protection develops to a challenge with recombinant vaccinia-gag virus at a mucosal surface, the airway. We suggest that a DEC-targeted vaccine, in part because of an unusually strong and protective CD4+ T cell response, will improve vaccine efficacy as a stand-alone approach or with other modalities
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Cis-Acting Regulation of Brain-Specific ANK3 Gene Expression by a Genetic Variant Associated with Bipolar Disorder
Several genome-wide association studies (GWAS) for bipolar disorder (BD) have found a strong association of the Ankyrin3 (ANK3) gene. This association spans numerous linked single nucleotide polymorphisms (SNPs) in a ~250 kb genomic region overlapping ANK3. The associated region encompasses predicted regulatory elements as well as two of six validated alternative first exons, which encode distinct protein domains at the N-terminus of the protein also known as ankyrin-G (AnkG). Using RNA Ligase-Mediated Rapid Amplification of cDNA Ends (RLM-RACE) to identify novel transcripts in conjunction with a highly sensitive, exon-specific multiplexed mRNA expression assay, we detected differential regulation of distinct ANK3 transcription start sites (TSSs) and coupling of specific 5â ends with 3â mRNA splicing events in post-mortem human brain and human stem cell-derived neural progenitors and neurons. Furthermore, allelic variation at the BDâassociated SNP rs1938526 correlated with a significant difference in cerebellar expression of a brain-specific ANK3 transcript. These findings suggest a brain-specific cis-regulatory transcriptional effect of ANK3 may be relevant to BD pathophysiology
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