52 research outputs found
The dustier early-type galaxies deviate from late-type galaxies\u27 scaling relations
Several dedicated surveys focusing on early-type galaxies (ETGs) reveal that significant fractions of them are detectable in all interstellar medium phases studied to date. We select ETGs from the Herschel Reference Survey that have both far-infrared Herschel and either H I or CO detection (or both).We derive their star formation rates (SFRs), stellar masses and dust masses viamodelling their spectral energy distributions.We combine these with literature information on their atomic and molecular gas properties, in order to relate their star formation, total gas mass and dust mass on global scales. The ETGs deviate from the dust mass-SFR relation and the Schmidt-Kennicutt relation that SDSS star-forming galaxies define: compared to SDSS galaxies, ETGs have more dust at the same SFR, or less SFR at the same dust mass. When placing them in the M*-SFR plane, ETGs show a much lower specific SFR as compared to normal star-forming galaxies. ETGs show a large scatter compared to the Schmidt-Kennicutt relation found locally within our Galaxy, extending to lower SFRs and gas mass surface densities. Using an ETG\u27s SFR and the Schmidt-Kennicutt law to predict its gas mass leads to an underestimate. ETGs have similar observed-gas-to-modelled-dust mass ratios to star-forming galaxies of the same stellar mass, as well as they exhibit a similar scatter
The massive star population of the Virgo Cluster galaxy NGC 4535
We analyzed the massive star population of the Virgo Cluster galaxy NGC 4535
using archival Hubble Space Telescope Wide Field Planetary Camera 2 images in
filters F555W and F814W, equivalent to Johnson V and Kron-Cousins I. We
performed high precision point spread function fitting photometry of 24353
sources including 3762 candidate blue supergiants, 841 candidate yellow
supergiants and 370 candidate red supergiants. We estimated the ratio of blue
to red supergiants as a decreasing function of galactocentric radius. Using
Modules for Experiments in Stellar Astrophysics isochrones at solar
metallicity, we defined the luminosity function and estimated the star
formation history of the galaxy over the last 60 Myrs. We conducted a
variability search in the V and I filters using three variability indexes: the
median absolute deviation, the interquartile range and the inverse von-Neumann
ratio. This analysis yielded 120 new variable candidates with absolute
magnitudes ranging from M = 4 to 11 mag. We used the MESA
evolutionary tracks at solar metallicity, to classify the variables based on
their absolute magnitude and their position on the color-magnitude diagram.
Among the new candidate variable sources are eight candidate variable red
supergiants, three candidate variable yellow supergiants and one candidate
luminous blue variable, which we suggest for follow-up observations.Comment: Accepted by A&A, 7 pages, 7 Tables, 53 figure
Multi-year chemical composition of the fine-aerosol fraction in Athens, Greece, with emphasis on the contribution of residential heating in wintertime
In an attempt to take effective action towards mitigating pollution episodes
in Athens, precise knowledge of PM2.5 composition and its sources is a
prerequisite. Thus, a 2-year chemical composition dataset from aerosol
samples collected in an urban background site in central Athens from
December 2013 to March 2016 has been obtained and a positive matrix
factorization (PMF) was applied in order to identify and apportion fine
aerosols to their sources. A total of 850 aerosol samples were collected on
a 12 to 24 h basis and analyzed for major ions, trace elements, and organic and
elemental carbon, allowing us to further assess the impact of residential
heating as a source of air pollution over Athens.The ionic and carbonaceous components were found to constitute the major
fraction of the PM2.5 aerosol mass. The annual contribution of the ion
mass (IM), particulate organic mass (POM), dust, elemental carbon (EC), and
sea salt (SS) was calculated at 31 %, 38 %, 18 %, 8 %, and
3 %, respectively, and exhibited considerable seasonal variation. In
winter, the share of IM was estimated down to 23 %, with POM + EC being the dominant component accounting for 52 % of the PM2.5 mass,
while in summer, IM (42 %) and carbonaceous aerosols (41 %)
contributed almost equally.Results from samples collected on a 12 h basis (day and night) during the
three intensive winter campaigns indicated the impact of heating on the
levels of a series of compounds. Indeed, PM2.5, EC, POM,
NO3−, C2O42−, non sea salt (nss) K+ and selected trace metals
including Cd and Pb were increased by up to a factor of 4 in the night
compared to the day, highlighting the importance of heating on air quality in
Athens. Furthermore, in order to better characterize wintertime aerosol
sources and quantify the impact of biomass burning on PM2.5 levels,
source apportionment was performed. The data can be interpreted on the basis
of six sources, namely biomass burning (31 %), vehicular emissions
(19 %), heavy oil combustion (7 %), regional secondary (21 %),
marine aerosols (9 %), and dust particles (8 %). Regarding
night-to-day patterns their contributions shifted from 19 %, 19 %,
8 %, 31 %, 12 %, and 10 % of the PM2.5 mass during day
to 39 %, 19 %, 6 %, 14 %, 7 %, and 7 % during the
night, underlining the significance of biomass burning as the main
contributor to fine particle levels during nighttime in winter.</p
Listeria monocytogenes in Milk Products
peer-reviewedMilk and milk products are frequently identified as vectors for transmission of Listeria monocytogenes. Milk can be contaminated at farm level either by indirect external contamination from the farm environment or less frequently by direct contamination of the milk from infection in the animal. Pasteurisation of milk will kill L. monocytogenes, but post-pasteurisation contamination, consumption of unpasteurised milk and manufacture of unpasteurised milk products can lead to milk being the cause of outbreaks of listeriosis. Therefore, there is a concern that L. monocytogenes in milk could lead to a public health risk. To protect against this risk, there is a need for awareness surrounding the issues, hygienic practices to reduce the risk and adequate sampling and analysis to verify that the risk is controlled. This review will highlight the issues surrounding L. monocytogenes in milk and milk products, including possible control measures. It will therefore create awareness about L. monocytogenes, contributing to protection of public health
Tonsillar Size in 2-to 14-Year-Old Children With and Without Snoring
Background: Few investigations have assessed tonsillar size in children of variable age, sleep-disordered breathing (SDB) status and degree of adiposity. This study evaluated the size of tonsils in young and older, lean and obese children, without or with snoring. Methods: Children attending the Emergency Department or Pulmonology Clinic were recruited and tonsillar size was scored 1-4. Snoring >= 1 night/week was considered diagnostic of SDB and body mass index z-score >= 1.645 was defined as obesity. Age was analyzed as dichotomous variable (7 years old). Results: 362 children (2-14 years old) were recruited; 78 (21.5 %) were obese and 108 (29.8 %) had SDB. SDB-but not age or obesity-was significantly related to tonsillar size (P = 0.001). There was not enough evidence to support the presence of interactions between SDB and age or obesity regarding the size of tonsils (P = 0.157 and P = 0.978, respectively). Young subjects without SDB had larger tonsils than older subjects without SDB (1.9 +/- 0.7 vs. 1.7 +/- 0.8; P = 0.017), whereas age did not affect tonsillar size in children with SDB (P = 0.78). Conclusions: Young and older children with SDB have similar tonsillar size. In contrast, older subjects without snoring have smaller tonsils than young subjects without snoring. Tonsillar enlargement in children with SDB probably occurs in early childhood without change in older age. Pediatr Pulmonol. 2009; 44:1216-1222. (C) 2009 Wiley-Liss, Inc
Long-term visibility variation in Athens (1931–2013): a proxy for local and regional atmospheric aerosol loads
This study explores the interdecadal variability and
trends of surface horizontal visibility at the urban area of Athens from
1931 to 2013, using the historical archives of the National Observatory of
Athens (NOA). A prominent deterioration of visibility in the city was
detected, with the long-term linear trend amounting to −2.8 km decade<sup>−1</sup>
(<i>p</i> < 0.001), over the entire study period. This was not accompanied
by any significant trend in relative humidity or precipitation over
the same period. A slight recovery of visibility levels seems to be
established in the recent decade (2004–2013). It was found that very good
visibility (> 20 km) occurred at a frequency of 34 % before the
1950s, while this percentage drops to just 2 % during the decade
2004–2013. The rapid impairment of the visual air quality in Athens around
the 1950s points to the increased levels of air pollution on a local
and/or regional scale, related to high urbanization rates and/or increased
anthropogenic emissions on a global scale at that period. Visibility was
found to be negatively/positively correlated with relative humidity/wind speed, the correlation being statistically valid at certain
periods. Wind regime and mainly wind direction and corresponding air mass
origin were found to highly control visibility levels in Athens. The
comparison of visibility variation in Athens and at a non-urban reference
site on Crete island revealed similar negative trends over the common
period of observations. This suggests that apart local sources, visibility
in Athens is highly determined by aerosol load of regional origin. AVHRR and
MODIS satellite-derived aerosol optical depth (AOD) retrievals over Athens
and surface measurements of PM<sub>10</sub> confirmed the relation of visibility
to aerosol load
Expression of Leukotriene Biosynthetic Enzymes in Tonsillar Tissue of Children With Obstructive Sleep Apnea A Prospective Nonrandomized Study
IMPORTANCE Cysteinyl leukotrienes (CysLTs) potentially promote adenotonsillar hypertrophy in children with obstructive sleep apnea (OSA). Previous studies have identified CysLTs and their receptors in tonsillar tissue from children with OSA. OBJECTIVE To demonstrate expression of the leukotriene biosynthetic enzymes 5-lipoxygenase (5-LO), 5-lipoxygenase activating protein (FLAP), leukotriene A(4) hydrolase (LTA(4)H), and leukotriene C-4 synthase (LTC4S) in T and B tonsillar lymphocytes from pediatric patients with OSA. It was hypothesized that children with OSA have greater expression of biosynthetic enzymes for CysLTs (5-LO, FLAP, and LTC4S) in their tonsillar tissue than do children with recurrent tonsillitis (RT), who were enrolled as controls. DESIGN, SETTING, AND PARTICIPANTS This prospective, nonrandomized study was performed at a tertiary care university hospital on 13 children with OSA and adenotonsillar hypertrophy undergoing adenotonsillectomy and 12 children without OSA also undergoing tonsillectomy for RT. Tonsillar tissue from children with OSA or RT was examined for 5-LO, FLAP, LTA(4)H, and LTC4S expression under real time-quantitative polymerase chain reaction (RT-qPCR), flow cytometry (FC), and confocal laser scanning microscopy (CM). MAIN OUTCOMES AND MEASURES Expression of biosynthetic enzymes for CysLTs (5-LO, FLAP, and LTC4S) was the main outcome measure. Patients with OSA and control patients with RT were compared for numbers of copies of 5-LO, FLAP, and LTC4S messenger RNA (by RT-qPCR) in T or B tonsillar lymphocytes and proportions of CD3(+) or CD19(+) tonsillar lymphocytes that expressed 5-LO, FLAP, and LTC4S (by FC). RESULTS Messenger RNA for all 4 enzymes was detected in T and B lymphocytes from both study groups, and expression of all biosynthetic enzymes was demonstrated in participants with OSA and RT by FC. Patients with OSA differed from controls in the proportions (median [10th-90th percentile]) of LTC4S+ CD3(+) T lymphocytes (23.31% [8.64%-50.07%] vs 10.81% [3.48%-23.32%], respectively) (P = .01) and LTC4S+ CD19(+) B lymphocytes (20.66% [14.62%-65.77%] vs 12.53%[2.87%-36.64%], respectively) (P = .01) detected by FC. Immunoreactivity for the 4 enzymes was detected by CM in B lymphocytes of mantle zones and T lymphocytes of extrafollicular areas. CONCLUSIONS AND RELEVANCE Leukotriene biosynthetic enzymes are expressed in tonsillar lymphocytes, and the previously reported detection of CysLTs in tonsillar tissue from children with OSA may be attributed to endogenous synthesis. Enhanced expression of LTC4S is a potential target for pharmacologic interventions in OSA
An improved cleaning protocol for foraminiferal calcite from unconsolidated core sediments: Hypercal—a new practice for micropaleontological and paleoclimatic proxies
Paleoclimatic and paleoceanographic studies routinely rely on the usage of foraminiferal calcite through faunal, morphometric and physico-chemical proxies. The application of such proxies presupposes the extraction and cleaning of these biomineralized components from ocean sediments in the most efficient way, a process which is often labor intensive and time consuming. In this respect, in this study we performed a systematic experiment for planktonic foraminiferal specimen cleaning using different chemical treatments and evaluated the resulting data of a Late Quaternary gravity core sample from the Aegean Sea. All cleaning procedures adopted here were made on the basis of their minimum potential bias upon foraminiferal proxies, such as the faunal assemblages, degree of fragmentation, stable isotope composition (δ18 O and δ13 C) and/or Mg/Ca ratios that are frequently used as proxies for surface-ocean climate parameters (e.g., sea surface temperature, sea surface salinity). Six different protocols were tested, involving washing, sieving, and chemical treatment of the samples with hydrogen peroxide and/or sodium hexametaphosphate (Calgon®). Single species foraminifera shell weighing was combined with high-resolution scanning electron microscopy (SEM) and synchrotron X-ray microtomography (SµCT) of the material processed by each of the cleaning protocols, in order to assess the decontamination degree of specimen’s ultrastructure and interior. It appeared that a good compromise between time and cleaning efficiency is the simultaneous treatment of samples with a mixed hydrogen peroxide and Calgon solution, while the most effective way to almost completely decontaminate the calcareous components from undesirable sedimentary material is a two-step treatment—initially with hydrogen peroxide and subsequently with Calgon solutions. © 2020 by the authors. Licensee MDPI, Basel, Switzerland
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