7,286 research outputs found
Regional differences of energetics, mechanics, and kinetics of myosin cross-bridge in human ureter smooth muscle
This study provides information about baseline mechanical properties of the entire muscle and the molecular contractile mechanism in human ureter smooth muscle and proposed to investigate if changes in mechanical motor performance in different regions of isolated human ureter are attributable to differences in myosin crossbridge
interactions. Classic mechanical, contraction and energetic parameters derived from the tension-velocity relationship were studied in ureteral smooth muscle strips oriented longitudinally and circularly from abdominal and pelvic human ureter parts. By applying of Huxley’s mathematical model we calculated the total working crossbridge number per mm2 (Ψ), elementary force per single crossbridge (Π0), duration of maximum rate constant of crossbridge attachment 1/f1 and detachment 1/g2 and peak mechanical efficiency (Eff.max). Abdominal longitudinal
smooth muscle strips exhibited significantly higher maximum isometric tension and faster maximum unloaded shortening velocity compared to pelvic ones. Contractile differences were associated with significantly higher crossbridge number per mm2. Abdominal longitudinal muscle strips showed a lower duration of maximum rate constant of crossbridge attachment and detachment and higher peak mechanical efficiency than pelvic ones. Such data suggest that the abdominal human ureter showed better mechanical motor performance mainly related to a higher
crossbridge number and crossbridge kinetics differences. Such results were more evident in the longitudinal rather than in the circular layer
Star Formation in Nearby Early-Type Galaxies: The Radio Continuum Perspective
We present a 1.4 GHz Karl G. Jansky Very Large Array (VLA) study of a sample
of early-type galaxies (ETGs) from the volume- and magnitude-limited ATLAS-3D
survey. The radio morphologies of these ETGs at a resolution of 5" are diverse
and include sources that are compact on sub-kpc scales, resolved structures
similar to those seen in star-forming spiral galaxies, and kpc-scale radio
jets/lobes associated with active nuclei. We compare the 1.4 GHz, molecular
gas, and infrared (IR) properties of these ETGs. The most CO-rich ATLAS-3D ETGs
have radio luminosities consistent with extrapolations from H_2-mass-derived
star formation rates from studies of late-type galaxies. These ETGs also follow
the radio-IR correlation. However, ETGs with lower molecular gas masses tend to
have less radio emission relative to their CO and IR emission compared to
spirals. The fraction of galaxies in our sample with high IR-radio ratios is
much higher than in previous studies, and cannot be explained by a systematic
underestimation of the radio luminosity due to the presence extended,
low-surface-brightness emission that was resolved-out in our VLA observations.
In addition, we find that the high IR-radio ratios tend to occur at low IR
luminosities, but are not associated with low dynamical mass or metallicity.
Thus, we have identified a population of ETGs that have a genuine shortfall of
radio emission relative to both their IR and molecular gas emission. A number
of mechanisms may conspire to cause this radio deficiency, including a
bottom-heavy stellar initial mass function, weak magnetic fields, a higher
prevalence of environmental effects compared to spirals and enhanced cosmic ray
losses.Comment: accepted for publication in MNRA
Modulation of LISA free-fall orbits due to the Earth-Moon system
We calculate the effect of the Earth-Moon (EM) system on the free-fall motion
of LISA test masses. We show that the periodic gravitational pulling of the EM
system induces a resonance with fundamental frequency 1 yr^-1 and a series of
periodic perturbations with frequencies equal to integer harmonics of the
synodic month (9.92 10^-7 Hz). We then evaluate the effects of these
perturbations (up to the 6th harmonics) on the relative motions between each
test masses couple, finding that they range between 3mm and 10pm for the 2nd
and 6th harmonic, respectively. If we take the LISA sensitivity curve, as
extrapolated down to 10^-6 Hz, we obtain that a few harmonics of the EM system
can be detected in the Doppler data collected by the LISA space mission. This
suggests that the EM system gravitational near field could provide an absolute
calibration for the LISA sensitivity at very low frequencies.Comment: 15 pages, 5 figure
The molecular polar disc in NGC 2768
We present CO(1-0) and CO(2-1) maps of the molecular polar disc in the
elliptical galaxy NGC 2768 obtained at the IRAM Plateau de Bure Interferometer.
The maps have a resolution of 2.6" x 2.3" and 1.2" x 1.2" for the CO(1-0) and
CO(2-1) lines, respectively. The CO maps complete the unique picture of the
interstellar medium (ISM) of NGC 2768; the dust, molecular gas, ionised gas and
neutral hydrogen (HI) trace the recent acquisition of cold and cool gas over
two orders of magnitude in radii (and much more in density). In agreement with
the other ISM components, the CO distribution extends nearly perpendicularly to
the photometric major axis of the galaxy. Velocity maps of the CO show a
rotating polar disc or ring in the inner kiloparsec. This cool gas could lead
to kinematic substructure formation within NGC 2768. However, the stellar
velocity field and H-beta absorption linestrength maps from the optical
integral-field spectrograph SAURON give no indication of a young and
dynamically cold stellar population coincident with the molecular polar disc.
Very recent or weak star formation, undetectable in linestrengths, nevertheless
remains a possibility and could be at the origin of some of the ionised gas
observed. Millimetre continuum emission was also detected in NGC 2768, now one
of only a few low-luminosity active galactic nuclei with observed millimetre
continuum emission.Comment: Accepted for publication in MNRAS, 11 pages, 8 figure
Harbor and intra-city drivers of air pollution: findings from a land use regression model, Durban, South Africa
Multiple land use regression models (LUR) were developed for different air pollutants to characterize exposure, in the Durban metropolitan area, South Africa. Based on the European Study of Cohorts for Air Pollution Effects (ESCAPE) methodology, concentrations of particulate matter (PM; 10; and PM; 2.5; ), sulphur dioxide (SO; 2; ), and nitrogen dioxide (NO; 2; ) were measured over a 1-year period, at 41 sites, with Ogawa Badges and 21 sites with PM Monitors. Sampling was undertaken in two regions of the city of Durban, South Africa, one with high levels of heavy industry as well as a harbor, and the other small-scale business activity. Air pollution concentrations showed a clear seasonal trend with higher concentrations being measured during winter (25.8, 4.2, 50.4, and 20.9 µg/m; 3; for NO; 2; , SO; 2; , PM; 10; , and PM; 2.5; , respectively) as compared to summer (10.5, 2.8, 20.5, and 8.5 µg/m; 3; for NO; 2; , SO; 2; , PM; 10; , and PM; 2.5; , respectively). Furthermore, higher levels of NO; 2; and SO; 2; were measured in south Durban as compared to north Durban as these are industrial related pollutants, while higher levels of PM were measured in north Durban as compared to south Durban and can be attributed to either traffic or domestic fuel burning. The LUR NO; 2; models for annual, summer, and winter explained 56%, 41%, and 63% of the variance with elevation, traffic, population, and Harbor being identified as important predictors. The SO; 2; models were less robust with lower R; 2; annual (37%), summer (46%), and winter (46%) with industrial and traffic variables being important predictors. The R; 2; for PM; 10; models ranged from 52% to 80% while for PM; 2.5; models this range was 61-76% with traffic, elevation, population, and urban land use type emerging as predictor variables. While these results demonstrate the influence of industrial and traffic emissions on air pollution concentrations, our study highlighted the importance of a Harbor variable, which may serve as a proxy for NO; 2; concentrations suggesting the presence of not only ship emissions, but also other sources such as heavy duty motor vehicles associated with the port activities
Cognitive and Structural Correlates of Conversational Speech Timing in Mild Cognitive Impairment and Mild-to-Moderate Alzheimer’s Disease : Relevance for Early Detection Approaches.
FUNDING This study was supported by a Centre for Ageing Research and Development in Ireland (CARDI) Leadership Fellowship (grant number 13533).Peer reviewedPublisher PD
Proteins associated with pancreatic cancer survival in patients with resectable pancreatic ductal adenocarcinoma.
Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease with a dismal prognosis. However, while most patients die within the first year of diagnosis, very rarely, a few patients can survive for >10 years. Better understanding the molecular characteristics of the pancreatic adenocarcinomas from these very-long-term survivors (VLTS) may provide clues for personalized medicine and improve current pancreatic cancer treatment. To extend our previous investigation, we examined the proteomes of individual pancreas tumor tissues from a group of VLTS patients (survival ≥10 years) and short-term survival patients (STS, survival <14 months). With a given analytical sensitivity, the protein profile of each pancreatic tumor tissue was compared to reveal the proteome alterations that may be associated with pancreatic cancer survival. Pathway analysis of the differential proteins identified suggested that MYC, IGF1R and p53 were the top three upstream regulators for the STS-associated proteins, and VEGFA, APOE and TGFβ-1 were the top three upstream regulators for the VLTS-associated proteins. Immunohistochemistry analysis using an independent cohort of 145 PDAC confirmed that the higher abundance of ribosomal protein S8 (RPS8) and prolargin (PRELP) were correlated with STS and VLTS, respectively. Multivariate Cox analysis indicated that 'High-RPS8 and Low-PRELP' was significantly associated with shorter survival time (HR=2.69, 95% CI 1.46-4.92, P=0.001). In addition, galectin-1, a previously identified protein with its abundance aversely associated with pancreatic cancer survival, was further evaluated for its significance in cancer-associated fibroblasts. Knockdown of galectin-1 in pancreatic cancer-associated fibroblasts dramatically reduced cell migration and invasion. The results from our study suggested that PRELP, LGALS1 and RPS8 might be significant prognostic factors, and RPS8 and LGALS1 could be potential therapeutic targets to improve pancreatic cancer survival if further validated
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