765 research outputs found
Comparative morphology of male genital skeletomusculature in the Leptanillinae (Hymenoptera: Formicidae), with a standardized muscular terminology for the male genitalia of Hymenoptera
The male genitalia of the Insecta are famed for structural and functional diversity. Variation in this anatomical region shows ample phylogenetic signal, and this variation has proven indispensable for classification across the insects at multiple taxonomic ranks. However, in the ants (Hymenoptera: Formicidae) the male genital phenotype is ancillary to the morphology of the worker caste for systematic purposes. Ants of the enigmatic subfamily Leptanillinae are an exception, as males are easier to collect than workers. Ongoing systematic revision of the Leptanillinae must therefore rely upon the male phenotype – particularly the spectacular morphological profusion of the male genitalia. To thoroughly illuminate this anatomical region and aid comparative morphological research on ant male genitalia, we present a comparative morphological study of the male genitalia in nine exemplar lineages spanning the Leptanillinae, plus three outgroups representing other major clades of the Formicidae. We use micro-computed tomography (micro-CT) to generate 3D volumetric reconstructions of male genital skeletomusculature in these specimens. Our descriptions use new muscular terminology compatible with topographic main-group systems for the rest of the pterygote soma, and applicable to all Hymenoptera. We find that male genitalia in the Leptanillinae show an overall trend towards skeletomuscular simplification, with muscular reduction in some cases being unprecedented in ants, or even hymenopterans in general. In several lineages of the Leptanillinae we describe derivations of the male genitalia that are bizarre and unparalleled among the Hymenoptera. We conclude by discussing the functional implications of the often-extreme morphologies here observed
A study of Traveling Ionospheric Disturbances and Atmospheric Gravity Waves using EISCAT Svalbard Radar IPY-data
We present a statistical study of Traveling Ionospheric
Disturbances (TIDs) as observed by the EISCAT Svalbard Radar (ESR) during the
continuous IPY-run (March 2007–February 2008) with field-aligned
measurements. We have developed a semi-automatic routine for searching and
extracting Atmospheric Gravity Wave (AGW) activity. The collected data shows
that AGW-TID signatures are common in the high-latitude ionosphere especially
in the field-aligned ion velocity data (244 cases of AGW-TID signatures in
daily records), but they can be observed also in electron density (26 cases),
electron temperature (12 cases) and ion temperature (26 cases). During the
IPY campaign (in solar minimum conditions) AGW-TID events appear more
frequently during summer months than during the winter months. It remains
still as a topic for future studies whether the observed seasonal variation
is natural or caused by seasonal variation in the performance of the
observational method that we use (AGW-TID signature may be more pronounced in
a dense ionosphere). In our AGW-TID dataset the distribution of the
oscillation periods has two peaks, one around 0.5–0.7 h and the other
around 1.1–1.3 h. The diurnal occurrence rate has a deep minimum in the
region of magnetic midnight, which might be partly explained by irregular
auroral activity obscuring the TID signatures from our detection routines. As
both the period and horizontal phase speed estimates (as derived from the
classical AGW dispersion relation) show values typical both for large scale
TIDs and mesoscale TIDs it is difficult to distinguish whether the generator
for high-latitude AGW-TIDs resides typically in the troposphere or in the
near-Earth space. The results of our statistical analysis give anyway some
valuable reference information for the future efforts to learn more about the
dominating TID source mechanisms in polar cap conditions, and to improve AGW
simulations
Spectra of equatorial total electron content derived from GPS signals
High cadence GPS TEC signals collected on Ascension Island, South Atlantic Ocean, during sunspot minimum, and in Vanimo, Papua New Guinea, over half a solar cycle, have been analysed for their spectral properties. A new parameter <I>T<sub>k</sub></I> has been introduced to quantify the strength of TEC irregularities at a scale size of 1 km. The scintillation strength and the spectral index have been analysed as functions of each other, and of local time, season, location and sunspot number. The scintillation strength is highest in autumn and spring in both locations, although the quietest period is summer in Ascension and winter in Vanimo. The scintillation strength decreases with decreasing sunspot number, but is consistently lower in Vanimo than in Ascension. The spectral index decreases with scintillation strength, and increases during the hours of the evening. A method is developed to estimate <I>T<sub>k</sub></I> from the large data base of <I>S</I><sub>4</sub> measurements
COVID-19:Technology-Supported Remote Assessment of Pediatric Asthma at Home
The COVID-19 crisis has pressured hospital-based care for children with high-risk asthma as they have become deprived of regular clinical evaluations. However, COVID-19 also provided important lessons about implementing novel directions for care. Personalized eHealth technology, tailored to the individual and the healthcare system, could substitute elements of hospital care and facilitate early and appropriate medical anticipation in response to imminent loss of control. This perspective article discusses new approaches to the clinical, organizational, and scientific aspects of the use of eHealth technology in pediatric asthma care in times of COVID-19, as illustrated by a case report of an acute asthma exacerbation possibly caused by COVID-19 infection
GRACE and TIMI risk scores but not stress imaging predict long-term cardiovascular follow-up in patients with chest pain after a rule-out protocol
Objective To determine the long-term prognostic value of stress imaging and clinical risk scoring for cardiovascular mortality in chest pain patients after ruling out acute coronary syndrome (ACS). Methods A standard rule-out protocol was performed in emergency room patients with a normal or non-diagnostic admission electrocardiogram (ECG) within 6 h of chest 4 pain onset. ACS patients were identified by troponin T, recurrent angina and serial ECG. Dobutamine stress echocardiography (DSE) was performed after ACS was ruled out. Myocardial perfusion scintigraphy (MPS) was performed within 6 months in an outpatient setting according to the physician's discretion. Results 524 patients were included. GRACE and TIMI risk scores were 75 (57-96) and 1 (0-2) in the rule-out ACS group, and 89 (74-107) and 2 (1-3) in the ACS group, respectively (median, interquartile range). Follow-up (median 9.4 (8.9-10.0) years) was complete in 96%. 350 of 379 rule-out ACS patients had an interpretable DSE and 52 patients underwent an MPS. 21 of the rule-out ACS patients (6%) died of a cardiovascular cause compared with 24 (17%) ACS patients (p <0.001). For rule-out ACS patients, C-statistics were 0.829 and 0.803 for the GRACE and TIMI scores. In these patients, DSE and MPS outcome did not predict long-term cardiovascular mortality. In multivariate analysis, known chronic heart failure, ACE inhibitor use, and GRACE score were independent predictors of cardiovascular mortality. Conclusions TIMI and GRACE score but not DSE and MPS are accurate predictors of long-term cardiovascular mortality, even in chest pain patients with a normal or non-diagnostic electrocardiogram undergoing a rule-out protoco
Diatom Biogeography, Temporal Dynamics, and Links to Bacterioplankton across Seven Oceanographic Time-Series Sites Spanning the Australian Continent.
Diatom communities significantly influence ocean primary productivity and carbon cycling, but their spatial and temporal dynamics are highly heterogeneous and are governed by a complex diverse suite of abiotic and biotic factors. We examined the seasonal and biogeographical dynamics of diatom communities in Australian coastal waters using amplicon sequencing data (18S-16S rRNA gene) derived from a network of oceanographic time-series spanning the Australian continent. We demonstrate that diatom community composition in this region displays significant biogeography, with each site harbouring distinct community structures. Temperature and nutrients were identified as the key environmental contributors to differences in diatom communities at all sites, collectively explaining 21% of the variability observed in diatoms assemblages. However, specific groups of bacteria previously implicated in mutualistic ecological interactions with diatoms (Rhodobacteraceae, Flavobacteriaceae and Alteromonadaceae) also explained a further 4% of the spatial dynamics observed in diatom community structure. We also demonstrate that the two most temperate sites (Port Hacking and Maria Island) exhibited strong seasonality in diatom community and that at these sites, winter diatom communities co-occurred with higher proportion of Alteromonadaceae. In addition, we identified significant co-occurrence between specific diatom and bacterial amplicon sequence variants (ASVs), with members of the Roseobacter and Flavobacteria clades strongly correlated with some of the most abundant diatom genera (Skeletonema, Thalassiosira, and Cylindrotheca). We propose that some of these co-occurrences might be indicative of ecologically important interactions between diatoms and bacteria. Our analyses reveal that in addition to physico-chemical conditions (i.e., temperature, nutrients), the relative abundance of specific groups of bacteria appear to play an important role in shaping the spatial and temporal dynamics of marine diatom communities
The low-level radial velocity variability in Barnard's star (=GJ 699). Secular acceleration, indications for convective redshift, and planet mass limits
We report results from 2 1/2 yr of high precision radial velocity (RV)
monitoring of Barnard's star. The high RV measurement precision of the
VLT-UT2+UVES of 2.65 m/s made the following findings possible. (1) The first
detection of the change in the RV of a star caused by its space motion (RV
secular acceleration). (2) An anti-correlation of the measured RV with the
strength of the filling-in of the Halpha line by emission. (3) Very stringent
mass upper limits to planetary companions. Using only data from the first 2
years, we obtain a best-fit value for the RV secular acceleration of
5.15+/-0.89 m/s/yr. This agrees with the predicted value of 4.50 m/s/yr based
on the Hipparcos proper motion and parallax combined with the known absolute
radial velocity of the star. When the RV data of the last half-year are added
the best-fit slope is strongly reduced to 2.97+/-0.51 m/s/yr suggesting the
presence of additional RV variability in the star. Part of it can be attributed
to stellar activity as we demonstrate by correlating the residual RVs with an
index that describes the filling-in of the Halpha line by emission. A
correlation coefficient of -0.50 indicates that the appearance of active
regions causes a blueshift of photospheric absorption lines. Assuming that
active regions basically inhibit convection we discuss the possibility that the
fundamental (inactive) convection pattern in this M4V star produces a
convective redshift. We also determine upper limits to the projected mass msini
and to the true mass m of hypothetical planetary companions in circular orbits.
For the separation range 0.017-0.98 AU we exclude any planet with msini>0.12
Mjupiter and m>0.86 Mjupiter. Throughout the habitable zone, i.e. 0.034-0.082
AU, we exclude planets with msini>7.5 Mearth and m>3.1 Mneptune.Comment: 12 pages, 8 figures, LaTeX2e, A&A macro, psfig macro, accepted by A&
Human plasma phospholipid transfer protein increases the antiatherogenic potential of high density lipoproteins in transgenic mice
Plasma phospholipid transfer protein (PLTP) transfers phospholipids
between lipoprotein particles and alters high density lipoprotein (HDL)
subfraction patterns in vitro, but its physiological function is poorly
understood. Transgenic mice that overexpress human PLTP were generated.
Compared with wild-type mice, these mice show a 2.5- to 4.5-fold increase
in PLTP activity in plasma. This results in a 30% to 40% decrease of
plasma levels of HDL cholesterol. Incubation of plasma from transgenic
animals at 37 degrees C reveals a 2- to 3-fold increase in the formation
of pre-beta-HDL compared with plasma from wild-type mice. Although
pre-beta-HDL is normally a minor subfraction of HDL, it is known to be a
very efficient acceptor of peripheral cell cholesterol and a key mediator
in reverse cholesterol transport. Further experiments show that plasma
from transgenic animals is much more efficient in preventing the
accumulation of intracellular cholesterol in macrophages than plasma from
wild-type mice, despite lower total HDL concentrations. It is concluded
that PLTP can act as an antiatherogenic factor preventing cellular
cholesterol overload by generation of pre-beta-HDL
The radii of the nearby K5V and K7V stars 61 Cyg A & B - CHARA/FLUOR interferometry and CESAM2k modeling
Context: The main sequence binary star 61 Cyg (K5V+K7V) is our nearest
stellar neighbour in the northern hemisphere. This proximity makes it a
particularly well suited system for very high accuracy interferometric radius
measurements. Aims: Our goal is to constrain the poorly known evolutionary
status and age of this bright binary star. Methods: We obtained high accuracy
interferometric observations in the infrared K' band, using the CHARA/FLUOR
instrument. We then computed evolutionary models of 61 Cyg A & B with the
CESAM2k code. As model constraints, we used a combination of observational
parameters from classical observation methods (photometry, spectroscopy) as
well as our new interferometric radii. Results: The measured limb darkened disk
angular diameters are theta_LD(A) = 1.775 +/- 0.013 mas and theta_LD(B) = 1.581
+/- 0.022 mas, respectively for 61 Cyg A and B. Considering the high accuracy
parallaxes available, these values translate into photospheric radii of R(A) =
0.665 +/- 0.005 Rsun and R(B) = 0.595 +/- 0.008 Rsun. The new radii constrain
efficiently the physical parameters adopted for the modeling of both stars,
allowing us to predict asteroseismic frequencies based on our best-fit models.
Conclusions: The CESAM2k evolutionary models indicate an age around 6 Gyrs and
are compatible with small values of the mixing length parameter. The
measurement of asteroseismic oscillation frequencies in 61 Cyg A & B would be
of great value to improve the modeling of this important fiducial stellar
system, in particular to better constrain the masses.Comment: Accepted for publication in A&A, 8 page
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