248 research outputs found
Directly tracing the vertical stratification of molecules in protoplanetary disks
We aim to directly trace the vertical location of the emitting surface of
multiple molecular tracers in protoplanetary disks. Our sample of disks
includes Elias 2-27, WaOph 6 and the sources targeted by the MAPS ALMA Large
Program. The set of molecules studied include CO isotopologues in various
transitions, HCN, CN, H2CO, HCO+, C2H and c-C3H2. The vertical emitting region
is determined directly from the channel maps, implementing accurate masking of
the channel emission to recover the vertical location of the emission surface
even at large radial distances from the star and for low-SNR lines. The
vertical location of the emitting layer is obtained for 4-10 lines in each
disk. IM Lup, HD163296 and MWC 480 12CO and 13CO show vertical modulations,
which are coincident with dust gaps and kinematical perturbations. We also
present estimates of the gas pressure scale height in the disks from the MAPS
sample. Compared to physical-chemical models we find good agreement with the
vertical location of CO isotopologues. In HD 163296 CN and HCN trace a similar
intermediate layer, for the other disks, the UV flux tracers and the vertical
profiles of HCN and C2H are lower than predicted in theoretical models. HCN and
H2CO show a highly structured vertical profile, possibly indicative of
different formation pathways. It is possible to trace the vertical locations of
multiple molecular species that trace a wide variety of physical and chemical
disk properties. The distribution of CO isotopologues are found at a wide range
of vertical heights 0.5-0.05. Other molecular lines are mostly found
at 0.15. The vertical layering of molecules is in agreement with
theory in some systems, but not in all, therefore dedicated chemical-physical
models are needed to further study and understand the emission surfaces.Comment: Accepted for publication in A&A. 29 pages, 28 figure
Evidence for ubiquitous carbon grain destruction in hot protostellar envelopes
Earth is deficient in carbon and nitrogen by up to orders of
magnitude compared with the Sun. Destruction of (carbon- and nitrogen-rich)
refractory organics in the high-temperature planet forming regions could
explain this deficiency. Assuming a refractory cometary composition for these
grains, their destruction enhances nitrogen-containing oxygen-poor molecules in
the hot gas (K) after the initial formation and sublimation of
these molecules from oxygen-rich ices in the warm gas (K). Using
observations of high-mass protostars with ALMA, we find that
oxygen-containing molecules (CHOH and HNCO) systematically show no
enhancement in their hot component. In contrast, nitrogen-containing,
oxygen-poor molecules (CHCN and CHCN) systematically show an
enhancement of a factor in their hot component, pointing to
additional production of these molecules in the hot gas. Assuming only thermal
excitation conditions, we interpret these results as a signature of destruction
of refractory organics, consistent with the cometary composition. This
destruction implies a higher C/O and N/O in the hot gas than the warm gas,
while, the exact values of these ratios depend on the fraction of grains that
are effectively destroyed. This fraction can be found by future chemical models
that constrain C/O and N/O from the abundances of minor carbon, nitrogen and
oxygen carriers presented here.Comment: Accepted for publication in ApJ Letter
Involvement of institutions and local communities in turtles and cetacean monitoring and conservation in Maltese waters through networking
The loggerhead turtle (Caretta caretta) and the bottlenose dolphin (Tursiops
truncatus) are regularly found around Maltese waters, especially the former. However,
until recently, information on the populations and conservation status of both species
in the area was lacking. The EU LIFE+ project MIGRATE (LIFE11 NAT/MT/1070)
was carried out to address these information gaps by aiming to obtain more biotic data
on these species and to identify areas essential for the life cycle and reproduction of
these protected species in Maltese waters.
To achieve these aims, amongst others, a citizen science approach was chosen, with
the involvement of a number of institutes like the Maritime Squadron of the Armed
Forces of Malta (AFM) and that of the Civil Protection Department (CPD) as well as
local non-governmental organisations (NGOs) and other sea-user communities such
as divers.peer-reviewe
Sensory determinants of behavioral dynamics in Drosophila thermotaxis
Complex animal behaviors are built from dynamical relationships between sensory inputs, neuronal activity, and motor outputs in patterns with strategic value. Connecting these patterns illuminates how nervous systems compute behavior. Here, we study Drosophila larva navigation up temperature gradients toward preferred temperatures (positive thermotaxis). By tracking the movements of animals responding to fixed spatial temperature gradients or random temperature fluctuations, we calculate the sensitivity and dynamics of the conversion of thermosensory inputs into motor responses. We discover three thermosensory neurons in each dorsal organ ganglion (DOG) that are required for positive thermotaxis. Random optogenetic stimulation of the DOG thermosensory neurons evokes behavioral patterns that mimic the response to temperature variations. In vivo calcium and voltage imaging reveals that the DOG thermosensory neurons exhibit activity patterns with sensitivity and dynamics matched to the behavioral response. Temporal processing of temperature variations carried out by the DOG thermosensory neurons emerges in distinct motor responses during thermotaxis
Complex organic molecules in low-mass protostars on Solar System scales -- II. Nitrogen-bearing species
The chemical inventory of planets is determined by the physical and chemical
processes that govern the early phases of star formation. The aim is to
investigate N-bearing complex organic molecules towards two Class 0 protostars
(B1-c and S68N) at millimetre wavelengths with ALMA. Next, the results of the
detected N-bearing species are compared with those of O-bearing species for the
same and other sources. ALMA observations in Band 6 ( 1 mm) and Band 5
( 2 mm) are studied at 0.5" resolution, complemented by Band 3
( 3 mm) data in a 2.5" beam. NH2CHO, C2H5CN, HNCO, HN13CO, DNCO,
CH3CN, CH2DCN, and CHD2CN are identified towards the investigated sources.
Their abundances relative to CH3OH and HNCO are similar for the two sources,
with column densities that are typically an order of magnitude lower than those
of O-bearing species. The largest variations, of an order of magnitude, are
seen for NH2CHO abundance ratios with respect to HNCO and CH3OH and do not
correlate with the protostellar luminosity. In addition, within uncertainties,
the N-bearing species have similar excitation temperatures to those of
O-bearing species ( 100 300 K). The similarity of most abundances
with respect to HNCO, including those of CH2DCN and CHD2CN, hints at a shared
chemical history, especially the high D/H ratio in cold regions prior to star
formation. However, some of the variations in abundances may reflect the
sensitivity of the chemistry to local conditions such as temperature (e.g.
NH2CHO), while others may arise from differences in the emitting areas of the
molecules linked to their different binding energies in the ice. The two
sources discussed here add to the small number of sources with such a detailed
chemical analysis on Solar System scales. Future JWST data will allow a direct
comparison between the ice and gas abundances of N-bearing species.Comment: Accepted to A&A, 41 pages, 37 figure
Barriers-enablers-ownership approach: A mixed methods analysis of a social intervention to improve surgical antibiotic prescribing in hospitals
Objectives To assess an intervention for surgical antibiotic prophylaxis (SAP) improvement within surgical teams focused on addressing barriers and fostering enablers and ownership of guideline compliance. Design The Queensland Surgical Antibiotic Prophylaxis (QSAP) study was a multicentre, mixed methods study designed to address barriers and enablers to SAP compliance and facilitate engagement in self-directed audit/feedback and assess the efficacy of the intervention in improving compliance with SAP guidelines. The implementation was assessed using a 24-month interrupted time series design coupled with a qualitative evaluation. Setting The study was undertaken at three hospitals (one regional, two metropolitan) in Australia. Participants SAP-prescribing decisions for 1757 patients undergoing general surgical procedures from three health services were included. Six bimonthly time points, pre-implementation and post implementation of the intervention, were measured. Qualitative interviews were performed with 29 clinical team members. SAP improvements varied across site and time periods. Intervention QSAP embedded ownership of quality improvement in SAP within surgical teams and used known social influences to address barriers to and enablers of optimal SAP prescribing. Results The site that reported senior surgeon engagement showed steady and consistent improvement in prescribing over 24 months (prestudy and poststudy). Multiple factors, including resource issues, influenced engagement and sites/time points where these were present had no improvement in guideline compliance. Conclusions The barriers-enablers-ownership model shows promise in its ability to facilitate prescribing improvements and could be expanded into other areas of antimicrobial stewardship. Senior ownership was a predictor of success (or failure) of the intervention across sites and time periods. The key role of senior leaders in change leadership indicates the critical need to engage other specialties in the stewardship agenda. The influence of contextual factors in limiting engagement clearly identifies issues of resource distributions/inequalities within health systems as limiting antimicrobial optimisation potential
Co expression of SCF and KIT in gastrointestinal stromal tumours (GISTs) suggests an autocrine/paracrine mechanism
KIT is a tyrosine kinase receptor expressed by several tumours, which has for specific ligand the stem cell factor (SCF). KIT is the main oncogene in gastrointestinal stromal tumours (GISTs), and gain-of-function KIT mutations are present in 70% of these tumours. The aim of the study was to measure and investigate the mechanisms of KIT activation in 80 KIT-positive GIST patients. KIT activation was quantified by detecting phosphotyrosine residues in Western blotting. SCF production was determined by reverse transcriptase–PCR, ELISA and/or immunohistochemistry. Primary cultures established from three GISTs were also analysed. The results show that KIT activation was detected in all cases, even in absence of KIT mutations. The fraction of activated KIT was not correlated with the mutational status of GISTs. Membrane and soluble isoforms of SCF mRNA were present in all GISTs analysed. Additionally, SCF was also detected in up to 93% of GISTs, and seen to be present within GIST cells. Likewise, the two SCF mRNA isoforms were found to be expressed in GIST-derived primary cultures. Thus, KIT activation in GISTs may in part result from the presence of SCF within the tumours
Clinical characteristics and prognosis of osteosarcoma in young children: a retrospective series of 15 cases
<p>Abstract</p> <p>Background</p> <p>Osteosarcoma is the most common primary bone malignancy in childhood and adolescence. However, it is very rare in children under 5 years of age. Although studies in young children are limited in number, they all underline the high rate of amputation in this population, with conflicting results being recently reported regarding their prognosis.</p> <p>Methods</p> <p>To enhance knowledge on the clinical characteristics and prognosis of osteosarcoma in young children, we reviewed the medical records and histology of all children diagnosed with osteosarcoma before the age of five years and treated in SFCE (Société Française des Cancers et leucémies de l'Enfant) centers between 1980 and 2007.</p> <p>Results</p> <p>Fifteen patients from 7 centers were studied. Long bones were involved in 14 cases. Metastases were present at diagnosis in 40% of cases. The histologic type was osteoblastic in 74% of cases. Two patients had a relevant history. One child developed a second malignancy 13 years after osteosarcoma diagnosis.</p> <p>Thirteen children received preoperative chemotherapy including high-dose methotrexate, but only 36% had a good histologic response. Chemotherapy was well tolerated, apart from a case of severe late convulsive encephalopathy in a one-year-old infant. Limb salvage surgery was performed in six cases, with frequent mechanical and infectious complications and variable functional outcomes.</p> <p>Complete remission was obtained in 12 children, six of whom relapsed. With a median follow-up of 5 years, six patients were alive in remission, seven died of their disease (45%), in a broad range of 2 months to 8 years after diagnosis, two were lost to follow-up.</p> <p>Conclusions</p> <p>Osteosarcoma seems to be more aggressive in children under five years of age, and surgical management remains a challange.</p
Assessment of the current and emerging criteria for the histopathological classification of lung neuroendocrine tumours in the lungNENomics project
Background: Six thoracic pathologists reviewed 259 lung neuroendocrine tumours (LNETs) from the lungNENomics project, with 171 of them having associated survival data. This cohort presents a unique opportunity to assess the strengths and limitations of current World Health Organization (WHO) classification criteria and to evaluate the utility of emerging markers. Patients and methods: Patients were diagnosed based on the 2021 WHO criteria, with atypical carcinoids (ACs) defined by the presence of focal necrosis and/or 2-10 mitoses per 2 mm2. We investigated two markers of tumour proliferation: the Ki-67 index and phospho-histone H3 (PHH3) protein expression, quantified by pathologists and automatically via deep learning. Additionally, an unsupervised deep learning algorithm was trained to uncover previously unnoticed morphological features with diagnostic value. Results: The accuracy in distinguishing typical from ACs is hampered by interobserver variability in mitotic counting and the limitations of morphological criteria in identifying aggressive cases. Our study reveals that different Ki-67 cut-offs can categorise LNETs similarly to current WHO criteria. Counting mitoses in PHH3+ areas does not improve diagnosis, while providing a similar prognostic value to the current criteria. With the advantage of being time efficient, automated assessment of these markers leads to similar conclusions. Lastly, state-of-the-art deep learning modelling does not uncover undisclosed morphological features with diagnostic value. Conclusions: This study suggests that the mitotic criteria can be complemented by manual or automated assessment of Ki-67 or PHH3 protein expression, but these markers do not significantly improve the prognostic value of the current classification, as the AC group remains highly unspecific for aggressive cases. Therefore, we may have exhausted the potential of morphological features in classifying and prognosticating LNETs. Our study suggests that it might be time to shift the research focus towards investigating molecular markers that could contribute to a more clinically relevant morpho-molecular classification.</p
Additive QTLs on three chromosomes control flowering time in woodland strawberry (Fragaria vesca L.)
Flowering time is an important trait that affects survival, reproduction and yield in both wild and cultivated plants. Therefore, many studies have focused on the identification of flowering time quantitative trait locus (QTLs) in different crops, and molecular control of this trait has been extensively investigated in model species. Here we report the mapping of QTLs for flowering time and vegetative traits in a large woodland strawberry mapping population that was phenotyped both under field conditions and in a greenhouse after flower induction in the field. The greenhouse experiment revealed additive QTLs in three linkage groups (LG), two on both LG4 and LG7, and one on LG6 that explain about half of the flowering time variance in the population. Three of the QTLs were newly identified in this study, and one co-localized with the previously characterized FvTFL1 gene. An additional strong QTL corresponding to previously mapped PFRU was detected in both field and greenhouse experiments indicating that gene(s) in this locus can control the timing of flowering in different environments in addition to the duration of flowering and axillary bud differentiation to runners and branch crowns. Several putative flowering time genes were identified in these QTL regions that await functional validation. Our results indicate that a few major QTLs may control flowering time and axillary bud differentiation in strawberries. We suggest that the identification of causal genes in the diploid strawberry may enable fine tuning of flowering time and vegetative growth in the closely related octoploid cultivated strawberry.Peer reviewe
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