417 research outputs found
Malin 1: interacting galaxy pair?
Malin 1 is a unique, extraordinarily large low surface brightness galaxy. The
structure and the origins of the galaxy are poorly understood. The reason for
such a situation is an absence of detailed observational data, especially, of
high-resolution kinematics. In this Letter we study the stellar kinematics of
the inner part (r < 15 kpc) of Malin 1. We present spectroscopic arguments in
favour of a small galaxy - Malin 1B - being a companion probably interacting
with the main galaxy - Malin 1. This object is clearly seen in many published
images of Malin 1 but is not mentioned in any astronomical databases. Malin 1B
is located at the projected distance of 14 kpc from the Malin 1's nucleus and
has small - 6516 km/s - relative velocity, which we determined for the
first time. We suggest that ongoing interaction with Malin 1B can explain main
morphological features of the Malin 1's central region - two-armed spiral
structure, a bar, and an external one-armed spiral pattern. We also
investigated the large scale environment of Malin 1 and postulate that the
galaxy SDSS J123708.91+142253.2 might be responsible for the formation of
extended low-surface brightness envelope by means of head-on collision with
Malin 1 (in the framework of collision scenario proposed by Mapelli et al.
2008). To test the collisional origins of Malin 1 global structure, more
observational data and new numerical models are needed.Comment: 5 pages, 4 figures, accepted for publication in MNRA
Changes in the folding landscape of the WW domain provide a molecular mechanism for an inherited genetic syndrome
WW domains are small domains present in many human proteins with a wide array of functions and acting through the recognition of proline-rich sequences. The WW domain belonging to polyglutamine tract-binding protein 1 (PQBP1) is of particular interest due to its direct involvement in several X chromosome-linked intellectual disabilities, including Golabi-Ito-Hall (GIH) syndrome, where a single point mutation (Y65C) correlates with the development of the disease. The mutant cannot bind to its natural ligand WBP11, which regulates mRNA processing. In this work we use high-field high-resolution NMR and enhanced sampling molecular dynamics simulations to gain insight into the molecular causes the disease. We find that the wild type protein is partially unfolded exchanging among multiple beta-strand-like conformations in solution. The Y65C mutation further destabilizes the residual fold and primes the protein for the formation of a disulphide bridge, which could be at the origin of the loss of function
GEOCHEMICAL INVESTIGATION OF AQUIFER POLLUTION FROM WASTE MANAGEMENT. THE CASE OF KOMOTINI LANDFILL (GREECE)
According to European legislation, environmental control and monitoring of landfills has become of crucial importance. This study includes a thorough geochemical approach aiming to evaluate the environmental impact of the landfill of Komotini, N. Greece. Samples of waters were taken from inside the working landfill as well as from the area of the neighbouring old landfill. The waters were analyzed chemically (major elements and heavy metals) and isotopically (D and 18O). Also, biogas flow was measured and the ratio CH4/CO2. Based on the geomorphological, hydrogeological and land use data of the area, we proceeded to analyses of waters both from the area of the landfill and from the wider region (drainage basin). The obtained results were used to construct digital maps (GIS) in order to determine the special dispersion of the polluted aquifers. The biogas flow in the old and new garbage burial sites was measured by accumulation chamber device for methane and carbon dioxide ratio determination. The obtained results show an important agent of pollution in the water samples downstream from the landfill and in a distance more than 2km, along the dispersion of the leachate. The land use of the area was taken into account to evaluate the importance and the criticality of the situation
Why Me? To Be an Ultra-Responder to Antiplatelet Therapy: A Case Report
Background: Platelet function testing is a valid tool to investigate the clinical response to antiplatelet therapy in different clinical settings; in particular, it might supply helpful information in patients with cerebrovascular disease. Oral antiplatelet treatment, such as Aspirin (ASA) and Clopidogrel, is the gold standard in secondary stroke prevention of non-cardiogenic ischemic stroke; conversely, its application as a primary prevention therapy is not routinely recommended in patients with vascular risk factors. Multiple electrode platelet aggregometry (MEA) impedance aggregometer is a validated device to test platelet inhibition induced by ASA or Clopidogrel. Case Report: We report the case of a 78-year-old patient without relevant clinical history, taking ASA as primary prevention strategy, who was admitted for sudden onset of dysarthria and left facial hyposthenia during physical effort. Brain CT revealed two small subcortical bilateral spontaneous intracranial hemorrhages. Platelet aggregometry with MEA performed upon admission revealed a very strong platelet inhibition induced by ASA (result of the ASPI Test was 5 U, consistent with an ultra-responsiveness to ASA, and the cutoff value of correct responsiveness is <40 U). MRI at longitudinal follow-up revealed the presence of two small cavernous angioma underlying hemorrhagic spots. Conclusion: The evaluation of platelet reactivity in stroke patients undergoing antiplatelet therapies, not commonly performed in clinical practice, could be useful to optimize prevention strategies; the verification of the biological effectiveness of ASA or Clopidogrel could be a valid tool in the definition of each patient's risk profile, particularly in patients with cerebrovascular disease known to be at increased risk for both hemorrhagic and thrombotic complications
Do dogs and cats passively carry sars-cov-2 on hair and pads?
The epidemiological role of domestic animals in the spread and transmission of SARS-CoV-2 to humans has been investigated in recent reports, but some aspects need to be further clarified. To date, only in rare cases have dogs and cats living with COVID-19 patients been found to harbour SARS-CoV-2, with no evidence of pet-to-human transmission. The aim of the present study was to verify whether dogs and cats act as passive mechanical carriers of SARS-CoV-2 when they live in close contact with COVID-19 patients. Cutaneous and interdigital swabs collected from 48 dogs and 15 cats owned by COVID-19 patients were tested for SARS-CoV-2 by qRT-PCR. The time elapsed between owner swab positivity and sample collection from pets ranged from 1 to 72 days, with a median time of 23 days for dogs and 39 days for cats. All samples tested negative, suggesting that pets do not passively carry SARS-CoV-2 on their hair and pads, and thus they likely do not play an important role in the virus transmission to humans. This data may contribute to confirming that the direct contact with the hair and pads of pets does not represent a route for the transmission of SARS-CoV-2
An Allosteric Cross-Talk Between the Activation Loop and the ATP Binding Site Regulates the Activation of Src Kinase
Phosphorylation of the activation loop is a fundamental step in the activation of most protein kinases. In the case of the Src tyrosine kinase, a prototypical kinase due to its role in cancer and its historic importance, phosphorylation of tyrosine 416 in the activation loop is known to rigidify the structure and contribute to the switch from the inactive to a fully active form. However, whether or not phosphorylation is able per-se to induce a fully active conformation, that efficiently binds ATP and phosphorylates the substrate, is less clear. Here we employ a combination of solution NMR and enhanced-sampling molecular dynamics simulations to fully map the effects of phosphorylation and ATP/ADP cofactor loading on the conformational landscape of Src tyrosine kinase. We find that both phosphorylation and cofactor binding are needed to induce a fully active conformation. What is more, we find a complex interplay between the A-loop and the hinge motion where the phosphorylation of the activation-loop has a significant allosteric effect on the dynamics of the C-lobe
String Theoretical Interpretation for Finite N Yang-Mills Theory in Two-Dimensions
We discuss the equivalence between a string theory and the two-dimensional
Yang-Mills theory with SU(N) gauge group for finite N. We find a sector which
can be interpreted as a sum of covering maps from closed string world-sheets to
the target space, whose covering number is less than N. This gives an
asymptotic expansion of 1/N whose large N limit becomes the chiral sector
defined by D.Gross and W.Taylor. We also discuss that the residual part of the
partition function provides the non-perturbative corrections to the
perturbative expansion.Comment: 15 pages, no figures, LaTeX2e, typos corrected, final version to
appear in Modern Physics Letters
Adaptive partitioning of real-time tasks on multiple processors
This paper presents a new algorithm for scheduling real-time tasks on multiprocessor/multicore systems. This new algorithm is based on combining EDF scheduling with a migration strategy that moves tasks only when needed. It has been evaluated through an extensive set of simulations that showed good performance when compared with global or partitioned EDF: a worst-case utilisation bound similar to partitioned EDF for hard real-time tasks, and a tardiness bound similar to global EDF for soft real-time tasks. Therefore, the proposed scheduler is effective for dealing with both soft and hard real-time workloads
Unveiling Relations in the Industry 4.0 Standards Landscape based on Knowledge Graph Embeddings
Industry~4.0 (I4.0) standards and standardization frameworks have been
proposed with the goal of \emph{empowering interoperability} in smart
factories. These standards enable the description and interaction of the main
components, systems, and processes inside of a smart factory. Due to the
growing number of frameworks and standards, there is an increasing need for
approaches that automatically analyze the landscape of I4.0 standards.
Standardization frameworks classify standards according to their functions into
layers and dimensions. However, similar standards can be classified differently
across the frameworks, producing, thus, interoperability conflicts among them.
Semantic-based approaches that rely on ontologies and knowledge graphs, have
been proposed to represent standards, known relations among them, as well as
their classification according to existing frameworks. Albeit informative, the
structured modeling of the I4.0 landscape only provides the foundations for
detecting interoperability issues. Thus, graph-based analytical methods able to
exploit knowledge encoded by these approaches, are required to uncover
alignments among standards. We study the relatedness among standards and
frameworks based on community analysis to discover knowledge that helps to cope
with interoperability conflicts between standards. We use knowledge graph
embeddings to automatically create these communities exploiting the meaning of
the existing relationships. In particular, we focus on the identification of
similar standards, i.e., communities of standards, and analyze their properties
to detect unknown relations. We empirically evaluate our approach on a
knowledge graph of I4.0 standards using the Trans family of embedding
models for knowledge graph entities. Our results are promising and suggest that
relations among standards can be detected accurately.Comment: 15 pages, 7 figures, DEXA2020 Conferenc
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