216 research outputs found
Line Profiles of Cores within Clusters. III. What is the most reliable tracer of core collapse in dense clusters?
Recent observational and theoretical investigations have emphasised the
importance of filamentary networks within molecular clouds as sites of star
formation. Since such environments are more complex than those of isolated
cores, it is essential to understand how the observed line profiles from
collapsing cores with non-spherical geometry are affected by filaments. In this
study, we investigate line profile asymmetries by performing radiative transfer
calculations on hydrodynamic models of three collapsing cores that are embedded
in filaments. We compare the results to those that are expected for isolated
cores. We model the five lowest rotational transition line (J = 1-0, 2-1, 3-2,
4-3, and 5-4) of both optically thick (HCN, HCO) as well as optically thin
(NH, HCO) molecules using constant abundance laws. We find
that less than 50% of simulated (1-0) transition lines show blue infall
asymmetries due to obscuration by the surrounding filament. However, the
fraction of collapsing cores that have a blue asymmetric emission line profile
rises to 90% when observed in the (4-3) transition. Since the densest gas
towards the collapsing core can excite higher rotational states, upper level
transitions are more likely to produce blue asymmetric emission profiles. We
conclude that even in irregular, embedded cores one can trace infalling gas
motions with blue asymmetric line profiles of optically thick lines by
observing higher transitions. The best tracer of collapse motions of our sample
is the (4-3) transition of HCN, but the (3-2) and (5-4) transitions of both HCN
and HCO are also good tracers.Comment: accepted by MNRAS; 13 pages, 16 figures, 6 table
Asymptotic linking of volume-preserving actions of
We extend V. Arnold's theory of asymptotic linking for two volume preserving
flows on a domain in and to volume preserving actions of
and on certain domains in
and also to linking of a volume preserving action of with a
closed oriented singular -dimensional submanifold in ,
where . We also extend the Biot-Savart formula to higher
dimensions.Comment: 32 pages. We extend Arnol'd's asymptotic linking to actions of
{\mathbb^R}^k and {\mathbb^R}^\ell. The only change in this version is
that several latex errors and internal references were corrected. The MSC
2020 classification was correcte
Sensor networks security based on sensitive robots agents. A conceptual model
Multi-agent systems are currently applied to solve complex problems. The
security of networks is an eloquent example of a complex and difficult problem.
A new model-concept Hybrid Sensitive Robot Metaheuristic for Intrusion
Detection is introduced in the current paper. The proposed technique could be
used with machine learning based intrusion detection techniques. The new model
uses the reaction of virtual sensitive robots to different stigmergic variables
in order to keep the tracks of the intruders when securing a sensor network.Comment: 5 page
Selection of elms tolerant to Dutch elm Disease in south-west Romania
Ophoiostoma novo- ulmi continues to be one of the most dangerous invasive fungi, destroying
many autochthonous elm forests and cultures throughout the world. Searching for natural genotypes
tolerant to Dutch Elm Disease (DED) is one of the main objectives of silviculturists all over the
northern hemisphere in order to save the susceptible elms and to restore their ecosystem biodiversity.
In this regard, the first trial was established between 1991 and 1994, in south-west Romania (Padurea
Verde, Timis,
oara), using three elm species (Ulmus minor, U. glabra, and U. laevis) with 38 provenances.
A local strain of Ophiostoma novo-ulmi was used to artificially inoculate all elm variants and the DED
evolution was observed. Furthermore, in 2018–2021 the trial was inventoried to understand the local
genotype reaction to DED in the local environmental conditions after almost 30 years. The outcomes
of the present study proved the continuous presence of the infections in the comparative culture
and its proximity, but the identified pathogen had a new hybrid form (found for the first time in
Romania) between O. novo-ulmi ssp. Americana x O. novo-ulmi ssp. novo-ulmi. Wych elm (U. glabra)
was extremely sensitive to DED: only 12 trees (out of 69 found in 2018) survived in 2021, and only
one tree could be selected according to the adopted health criteria (resistance and vigour). The field
elm (U. minor) was sensitive to the pathogen, but there were still individuals that showed good health
status and growth. In contrast, the European white elm (U. laevis) proved constant tolerance to DED:
only 15% had been found dead or presented severe symptoms of dieback. Overall, the results of
this study report the diverse reactions of the Romanian regional elm genotypes to DED over the last
three decades, providing promising perspectives for improving the presence of elms in the forest
ecosystems of the Carpathian basin
How to stop disproportionation of a hydrochloride salt of a very weakly basic compound in a non-clinical suspension formulation
Our objectives were to stabilize a non-clinical suspension for use in toxicological studies and to develop methods to investigate the stability of the formulation in terms of salt disproportionation. The compound under research was a hydrochloride salt of a practically insoluble discovery compound ODM-203. The first of the three formulation approaches was a suspension prepared and stored at room temperature. The second formulation was stabilized by pH adjustment. In the third approach cooling was used to prevent salt disproportionation. 5 mg/mL aqueous suspension consisting of 20 mg/mL PVP/VA and 5 mg/mL Tween 80 was prepared for each of the approaches. The polymer was used as precipitation inhibitor to provide prolonged supersaturation while Tween 80 was used to enhance dissolution and homogeneity of the suspension. The consequences of salt disproportionation were studied by a small-scale in vitro dissolution method and by an in vivo pharmacokinetic study in rats. Our results show that disproportionation was successfully suppressed by applying cooling of the suspension in an ice bath at 2-8 degrees C. This procedure enabled us to proceed to the toxicological studies in rats. The in vivo study results obtained for the practically insoluble compound showed adequate exposures with acceptable variation at each dose level.Peer reviewe
Hyperlipidemia and Atherosclerotic Lesion Development in Ldlr-Deficient Mice on a Long-Term High-Fat Diet
BACKGROUND: Mice deficient in the LDL receptor (Ldlr(-/-) mice) have been widely used as a model to mimic human atherosclerosis. However, the time-course of atherosclerotic lesion development and distribution of lesions at specific time-points are yet to be established. The current study sought to determine the progression and distribution of lesions in Ldlr(-/-) mice. METHODOLOGY/PRINCIPAL FINDINGS: Ldlr-deficient mice fed regular chow or a high-fat (HF) diet for 0.5 to 12 months were analyzed for atherosclerotic lesions with en face and cross-sectional imaging. Mice displayed significant individual differences in lesion development when fed a chow diet, whereas those on a HF diet developed lesions in a time-dependent and site-selective manner. Specifically, mice subjected to the HF diet showed slight atherosclerotic lesions distributed exclusively in the aortic roots or innominate artery before 3 months. Lesions extended to the thoracic aorta at 6 months and abdominal aorta at 9 months. Cross-sectional analysis revealed the presence of advanced lesions in the aortic sinus after 3 months in the group on the HF diet and in the innominate artery at 6 to 9 months. The HF diet additionally resulted in increased total cholesterol, LDL, glucose, and HBA1c levels, along with the complication of obesity. CONCLUSIONS/SIGNIFICANCE: Ldlr-deficient mice on the HF diet tend to develop site-selective and size-specific atherosclerotic lesions over time. The current study should provide information on diet induction or drug intervention times and facilitate estimation of the appropriate locations of atherosclerotic lesions in Ldlr(-/-) mice
Relationship between the Sensory-Determined Astringency and the Flavanolic Composition of Red Wines
[EN] The relationship between the proanthocyanidin profile and the perceived astringency was assessed in 13 commercial Tempranillo red wines. The concentration and compositional information were obtained by liquid chromatography with diode array detection coupled to electrospray ionization mass spectrometry after acid-catalyzed depolymerization of wine proanthocyanidins in the presence of excess phloroglucinol. Statistical analysis of the results showed significant correlations between sensory and chemical determinations. Astringency was more affected by the subunit composition than by the total concentration or the average degree of polymerization of wine proanthocyanidins. Higher proportions of epicatechin (EC) subunits in extension positions and gallocatechin (GC) subunits in terminal positions were shown to increase astringency. On the contrary, the amount of epigallocatechin (EGC) in both extension and terminal positions was negatively correlated with the perceived astringency
The correlation of dust and gas emission in star-forming environments
We present ammonia maps of portions of the W3 and Perseus molecular clouds in order to compare gas emission with submillimetre continuum thermal emission which are commonly used to trace the same mass component in star-forming regions, often under the assumption of local thermodynamic equilibrium (LTE).
The Perseus and W3 star-forming regions are found to have significantly different physical characteristics consistent with the difference in size scales traced by our observations. Accounting for the distance of the W3 region does not fully reconcile these differences, suggesting that there may be an underlying difference in the structure of the two regions.
Peak positions of submillimetre and ammonia emission do not correlate strongly. Also, the extent of diffuse emission is only moderately matched between ammonia and thermal emission. Source sizes measured from our observations are consistent between regions, although there is a noticeable difference between the submillimetre source sizes with sources in Perseus being significantly smaller than those in W3.
Fractional abundances of ammonia are determined for our sources which indicate a dip in the measured ammonia abundance at the positions of peak submillimetre column density.
Virial ratios are determined which show that our sources are generally bound in both regions, although there is considerable scatter in both samples. We conclude that sources in Perseus are bound on smaller scales than in W3 in a way that may reflect their previous identification as low- and high-mass, respectively.
Our results indicate that assumptions of local thermal equilibrium and/or the coupling of the dust and gas phases in star-forming regions may not be as robust as commonly assumed
Grambank reveals the importance of genealogical constraints on linguistic diversity and highlights the impact of language loss
While global patterns of human genetic diversity are increasingly well characterized, the diversity of human languages remains less systematically described. Here we outline the Grambank database. With over 400,000 data points and 2,400 languages, Grambank is the largest comparative grammatical database available. The comprehensiveness of Grambank allows us to quantify the relative effects of genealogical inheritance and geographic proximity on the structural diversity of the world's languages, evaluate constraints on linguistic diversity, and identify the world's most unusual languages. An analysis of the consequences of language loss reveals that the reduction in diversity will be strikingly uneven across the major linguistic regions of the world. Without sustained efforts to document and revitalize endangered languages, our linguistic window into human history, cognition and culture will be seriously fragmented.Genealogy versus geography Constraints on grammar Unusual languages Language loss Conclusio
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