255 research outputs found
Zinc–meso-tetra-p-tolylporphyrin and its chlorotoluene channel-type clathrate with π–π and C—H⋯π interaction modes stabilizing the porphyrin host lattice
The title compound, (meso-5,10,15,20-tetra-p-tolyl-porphyrinato-N,N',N",N'" ) zinc (II), [Zn (C48H36N4) ], displays a high tendency to form complexes and clathrates with other components from various environments, and is a useful building block for the construction of heteromolecular solids. Modes of its intermolecular assembly in the pure compound and in its clathrate with m-chlorotoluene, [Zn(Ca48H36Na4)].C7H7Cl, have been characterized by X-ray crystal-structure analysis. The clathrate appears to be stabilized by 7r-Tr stacking and cooperative C--H...:r interactions between the tolyl substituents and contains large interporphyrin channels extending throughout the crystal
SN 2015ba: A type IIP supernova with a long plateau
We present optical photometry and spectroscopy from about a week after
explosion to 272 d of an atypical Type IIP supernova, SN 2015ba, which
exploded in the edge-on galaxy IC 1029. SN 2015ba is a luminous event with an
absolute V-band magnitude of -17.10.2 mag at 50 d since explosion and has
a long plateau lasting for 123 d. The distance to the SN is estimated to
be 34.80.7 Mpc using the expanding photosphere and standard candle
methods. High-velocity H-Balmer components constant with time are observed in
the late-plateau phase spectra of SN 2015ba, which suggests a possible role of
circumstellar interaction at these phases. Both hydrodynamical and analytical
modelling suggest a massive progenitor of SN 2015ba with a pre-explosion mass
of 24-26 M. However, the nebular spectra of SN 2015ba exhibit
insignificant levels of oxygen, which is otherwise expected from a massive
progenitor. This might be suggestive of the non-monotonical link between O-core
masses and the zero-age main-sequence mass of pre-supernova stars and/or
uncertainties in the mixing scenario in the ejecta of supernovae.Comment: 42 pages, 7 pages Appendix, 20 figures, 10 tables, Accepted for
publication in MNRAS, 14-June-201
Arrhythmogenic right ventricular cardiomyopathy (ARVC) mimics:the knot unravelled by cardiovascular MRI
Diagnostic yield of cardiovascular magnetic resonance in young-middle aged patients with high-grade atrio-ventricular block
A novel selection of optimal statistical features in the DWPT domain for discrimination of ictal and seizure-free electroencephalography signals
Properly determining the discriminative features which characterize the inherent behaviors of electroencephalography (EEG) signals remains a great challenge for epileptic seizure detection. In this present study, a novel feature selection scheme based on the discrete wavelet packet decomposition and cuckoo search algorithm (CSA) was proposed. The normal as well as epileptic EEG recordings were frst decomposed into various frequency bands by means of wavelet packet decomposition, and subsequently, statistical features at all developed nodes in the wavelet packet decomposition tree were derived. Instead of using the complete set of the extracted features to construct a wavelet neural networks-based classifer, an optimal feature subset that maximizes the predictive competence of the classifer was selected by using the CSA. Experimental results on the publicly available benchmarks demonstrated that the proposed feature subset selection scheme achieved promising recognition accuracies of 98.43–100%, and the results were statistically signifcant using z-test with p value <0.0001
Photometric and spectroscopic analysis of the Type II SN 2020jfo with a short plateau
We present high-cadence photometric and spectroscopic observations of
SN~2020jfo in ultraviolet and optical/near-infrared bands starting from to days after the explosion, including the earliest data with the
10.4\,m GTC. SN~2020jfo is a hydrogen-rich Type II SN with a relatively short
plateau duration ( days). When compared to other Type II
supernovae (SNe) of similar or shorter plateau lengths, SN~2020jfo exhibits a
fainter peak absolute -band magnitude ( mag).
SN~2020jfo shows significant H absorption in the plateau phase similar
to that of typical SNe~II. The emission line of stable [Ni~II] 7378,
mostly seen in low-luminosity SNe~II, is very prominent in the nebular-phase
spectra of SN~2020jfo. Using the relative strengths of [Ni~II] 7378
and [Fe~II] 7155, we derive the Ni/Fe production (abundance) ratio of
0.08--0.10, which is times the solar value. The progenitor mass of
SN~2020jfo from nebular-phase spectral modelling and semi-analytical modelling
falls in the range of 12--15\,. Furthermore, semi-analytical modelling
suggests a massive H envelope in the progenitor of SN~2020jfo, which is
unlikely for SNe~II having short plateaus.Comment: 20 pages (plus 5 pages appendix), 19 figures, Accepted for
publication in MNRA
Non-Hodgkin lymphoma response evaluation with MRI texture classification
<p>Abstract</p> <p>Background</p> <p>To show magnetic resonance imaging (MRI) texture appearance change in non-Hodgkin lymphoma (NHL) during treatment with response controlled by quantitative volume analysis.</p> <p>Methods</p> <p>A total of 19 patients having NHL with an evaluable lymphoma lesion were scanned at three imaging timepoints with 1.5T device during clinical treatment evaluation. Texture characteristics of images were analyzed and classified with MaZda application and statistical tests.</p> <p>Results</p> <p>NHL tissue MRI texture imaged before treatment and under chemotherapy was classified within several subgroups, showing best discrimination with 96% correct classification in non-linear discriminant analysis of T2-weighted images.</p> <p>Texture parameters of MRI data were successfully tested with statistical tests to assess the impact of the separability of the parameters in evaluating chemotherapy response in lymphoma tissue.</p> <p>Conclusion</p> <p>Texture characteristics of MRI data were classified successfully; this proved texture analysis to be potential quantitative means of representing lymphoma tissue changes during chemotherapy response monitoring.</p
Discovery and Rapid Follow-up Observations of the Unusual Type II SN 2018ivc in NGC 1068
We present the discovery and high-cadence follow-up observations of SN 2018ivc, an unusual SNe II that
exploded in NGC 1068 (D = 10.1 Mpc). The light curve of SN 2018ivc declines piecewise-linearly, changing
slope frequently, with four clear slope changes in the first 30 days of evolution. This rapidly changing light
curve indicates that interaction between the circumstellar material and ejecta plays a significant role in the
evolution. Circumstellar interaction is further supported by a strong X-ray detection. The spectra are rapidly
evolving and dominated by hydrogen, helium, and calcium emission lines. We identify a rare high-velocity
emission-line feature blueshifted at ∼7800 - km s 1 (in Hα, Hβ, Pβ, Pγ, He I, and Ca II), which is visible from
day 18 until at least day 78 and could be evidence of an asymmetric progenitor or explosion. From the overall
similarity between SN 2018ivc and SN 1996al, the Hα equivalent width of its parent H II region, and
constraints from pre-explosion archival Hubble Space Telescope images, we find that the progenitor of
SN 2018ivc could be as massive as 52 M but is more likely <12 M. SN 2018ivc demonstrates the importance
of the early discovery and rapid follow-up observations of nearby supernovae to study the physics and
progenitors of these cosmic explosions
Observations of the luminous red nova AT 2021biy in the nearby galaxy NGC 4631
We present an observational study of the luminous red nova (LRN) AT\,2021biy
in the nearby galaxy NGC\,4631. The field of the object was routinely imaged
during the pre-eruptive stage by synoptic surveys, but the transient was
detected only at a few epochs from \,days before maximum brightness.
The LRN outburst was monitored with unprecedented cadence both photometrically
and spectroscopically. AT\,2021biy shows a short-duration blue peak, with a
bolometric luminosity of \,erg\,s, followed by
the longest plateau among LRNe to date, with a duration of 210\,days. A
late-time hump in the light curve was also observed, possibly produced by a
shell-shell collision. AT\,2021biy exhibits the typical spectral evolution of
LRNe. Early-time spectra are characterised by a blue continuum and prominent H
emission lines. Then, the continuum becomes redder, resembling that of a K-type
star with a forest of metal absorption lines during the plateau phase. Finally,
late-time spectra show a very red continuum ( K)
with molecular features (e.g., TiO) resembling those of M-type stars.
Spectropolarimetric analysis indicates that AT\,2021biy has local dust
properties similar to those of V838\,Mon in the Milky Way Galaxy. Inspection of
archival {\it Hubble Space Telescope} data taken on 2003 August 3 reveals a
\,\msun\ progenitor candidate with log\,\,dex and \,K at solar metallicity. The above
luminosity and colour match those of a luminous yellow supergiant. Most likely,
this source is a close binary, with a 17--24\,\msun\ primary component.Comment: 21 pages, 14 figures. Accepted by Astronomy and Astrophysic
The Microphenotron: a robotic miniaturized plant phenotyping platform with diverse applications in chemical biology
Background
Chemical genetics provides a powerful alternative to conventional genetics for understanding gene function. However, its application to plants has been limited by the lack of a technology that allows detailed phenotyping of whole-seedling development in the context of a high-throughput chemical screen. We have therefore sought to develop an automated micro-phenotyping platform that would allow both root and shoot development to be monitored under conditions where the phenotypic effects of large numbers of small molecules can be assessed.
Results
The ‘Microphenotron’ platform uses 96-well microtitre plates to deliver chemical treatments to seedlings of Arabidopsis thaliana L. and is based around four components: (a) the ‘Phytostrip’, a novel seedling growth device that enables chemical treatments to be combined with the automated capture of images of developing roots and shoots; (b) an illuminated robotic platform that uses a commercially available robotic manipulator to capture images of developing shoots and roots; (c) software to control the sequence of robotic movements and integrate these with the image capture process; (d) purpose-made image analysis software for automated extraction of quantitative phenotypic data. Imaging of each plate (representing 80 separate assays) takes 4 min and can easily be performed daily for time-course studies. As currently configured, the Microphenotron has a capacity of 54 microtitre plates in a growth room footprint of 2.1 m², giving a potential throughput of up to 4320 chemical treatments in a typical 10 days experiment. The Microphenotron has been validated by using it to screen a collection of 800 natural compounds for qualitative effects on root development and to perform a quantitative analysis of the effects of a range of concentrations of nitrate and ammonium on seedling development.
Conclusions
The Microphenotron is an automated screening platform that for the first time is able to combine large numbers of individual chemical treatments with a detailed analysis of whole-seedling development, and particularly root system development. The Microphenotron should provide a powerful new tool for chemical genetics and for wider chemical biology applications, including the development of natural and synthetic chemical products for improved agricultural sustainability
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