187 research outputs found
Linear radio structures in selected Seyfert and LINER galaxies
High resolution MERLIN 5 GHz observations (0.04") of 7 Seyfert galaxies,
selected as the ones previously showing evidence of collimated ejection, have
been compared with high resolution archive HST data. The radio maps reveal rich
structures in all the galaxies. NGC 2639 and TXFS 2226-184 have multiple knot
parsec-scale extended structures, Mrk 1034, Mrk 1210, NGC 4922C and NGC 5506
reveal one-sided jets, while IC 1481 exhibits a jet-like extension. The close
correlation between the radio-emitting relativistic plasma and the ionized gas
in the inner regions of these galaxies allows us to study in detail the physics
close to the center of low luminosity AGN.Comment: American Institute of Physics (AIP) Conference Series "Recent
Advances in Astronomy and Astrophysics
Aptamers as the Agent in Decontamination Assays (Apta-Decontamination Assays): From the Environment to the Potential Application In Vivo
The binding specificity and affinity of aptamers have long been harnessed as the key elements in the development of aptamerbased
assays, particularly aptasensing application. One promising avenue that is currently explored based on the specificity and
affinity of aptamers is the application of aptamers in the decontamination assays. Aptamers have been successfully harnessed
as the decontamination agents to remove contaminants from the environment and to decontaminate infectious elements. The
reversible denaturation property inherent in aptamers enables the repeated usage of aptamers, which can immensely save the cost of
decontamination. Analogous to the point-of-care diagnostics, there is no doubt that aptamers can also be deployed in the point-ofcare
aptamer-based decontamination assay, whereby decontamination can be performed anywhere and anytime for instantaneous
decision-making. It is also prophesied that aptamers can also serve more than as a decontaminant, probably as a tool to capture
and kill hazardous elements, particularly pathogenic agents
The Role of Pressure in GMC Formation II: The H_2 - Pressure Relation
We show that the ratio of molecular to atomic gas in galaxies is determined
by hydrostatic pressure and that the relation between the two is nearly linear.
The pressure relation is shown to be good over three orders of magnitude for 14
galaxies including dwarfs, HI-rich, and H_2-rich galaxies as well as the Milky
Way. The sample spans a factor of five in mean metallicity. The rms scatter of
individual points of the relation is only about a factor of two for all the
galaxies, though some show much more scatter than others. Using these results,
we propose a modified star formation prescription based on pressure determining
the degree to which the ISM is molecular. The formulation is different in high
and low pressure regimes defined by whether the gas is primarily atomic or
primarily molecular. This formulation can be implemented in simulations and
provides a more appropriate treatment of the outer regions of spiral galaxies
and molecule-poor systems such as dwarf irregulars and damped Lyman-alpha
systems.Comment: 14 pages, 7 figures, Accepted to the Astrophysical Journa
Sub-arcsecond imaging of the radio continuum and neutral hydrogen in the Medusa merger
We present sub-arcsecond, Multi-Element Radio Linked Interferometer (MERLIN)
observations of the decimetre radio continuum structure and neutral hydrogen
(HI) absorption from the nuclear region of the starburst galaxy NGC 4194 (the
Medusa Merger). The continuum structure of the central kiloparsec of the Medusa
has been imaged, revealing a pair of compact radio components surrounded by
more diffuse, weak radio emission. Using the constraints provided by these
observations and those within the literature we conclude that the majority of
this radio emission is related to the ongoing star-formation in this merger
system.
With these observations we also trace deep HI absorption across the detected
radio continuum structure. The absorbing HI gas structure exhibits large
variations in column densities. The largest column densities are found toward
the south of the nuclear radio continuum, co-spatial with both a nuclear dust
lane and peaks in CO (1->0) emission. The dynamics of the HI absorption,
which are consistent with lower resolution CO emission observations,
trace a shallow north-south velocity gradient of ~320km/s/kpc. This gradient is
interpreted as part of a rotating gas structure within the nuclear region. The
HI and CO velocity structure, in conjunction with the observed gas column
densities and distribution, is further discussed in the context of the fuelling
and gas physics of the ongoing starburst within the centre of this merger.Comment: 12 pages, 5 figures, to appear in A&
RNomic identification and evaluation of npcTB_6715, a nonprotein- coding RNA gene as a potential biomarker for the detection of Mycobacterium tuberculosis
Technological advances in RNA biology greatly improved transcriptome profiling during the last two decades. Besides the discovery of many
small RNAs (sRNA) that are involved in the physiological and pathophysiological regulation of various cellular circuits, it becomes evident that
the corresponding RNA genes might also serve as potential biomarkers to monitor the progression of disease and treatment. sRNA gene candidate
npcTB_6715 was previously identified via experimental RNomic (unpublished data), and we report its application as potential biomarker
for the detection of Mycobacterium tuberculosis (MTB) in patient samples. For proof of principle, we developed a multiplex PCR assay and
report its validation with 500 clinical cultures, positive for Mycobacteria. The analysis revealed 98.9% sensitivity, 96.1% specificity, positive and
negative predictive values of 98.6% and 96.8%, respectively. These results underscore the diagnostic value of the sRNA gene as diagnostic
marker for the specific detection of MTB in clinical samples. Its successful application and the general ease of PCR-based detection compared
to standard bacterial culture techniques might be the first step towards ‘point-of-care’ diagnostics of Mycobacteria. To the best of our knowledge,
this is the first time for the design of diagnostic applications based on sRNA genes, in Mycobacteria
Asymmetrical structure of ionization and kinematics in the Seyfert galaxy NGC 5033
We present integral field spectroscopy of NGC 5033, a low luminosity Seyfert
galaxy. The observations were made with INTEGRAL, a fiber based system
operating at the WHT. The intensity map of the H emission line
represents a spiral or ring-like pattern of HII regions. On the contrary, the
[OIII] intensity map morphology is markedly anisotropic. The strong
morphological differences imply that the [OIII] emitters represent highly
ionized gas illuminated by the central source. The [OIII] map morphology is
compatible with a biconical structure of ionization induced by strong
extinction in the galaxy disc that also obscures half of the spheroidal stellar
bulge. We identify the spectrum corresponding to the Seyfert 1 nucleus from the
presence of H broad emission lines. This spectrum is located in a region
where strong extinction is expected but exhibits the bluest spectral energy
distribution. The Seyfert 1 nucleus seems to be offcenter with respect to the
stellar rotation center. This result has been also found in other Seyfert
galaxies and interpreted in terms of a past merger. The offcentering could
indicate the presence of nonsymmetric departures in the gravitational potential
which could be fueling the active nucleus. The kinematics of the [OIII]
emitters show important deviations at a kpc scale with respect to the stellar
velocity field and show features related to the asymmetrical morphology of the
high ionization region.Comment: 9 pages, accepted for publication in Astronomy and Astrophysics.
Figures 1 and 7 are attached as .gif file
Rigorous Computational and Experimental Investigations on MDM2/MDMX-Targeted Linear and Macrocyclic Peptides
There is interest in peptide drug design, especially for targeting intracellular protein–protein interactions. Therefore, the experimental validation of a computational platform for enabling peptide drug design is of interest. Here, we describe our peptide drug design platform (CMDInventus) and demonstrate its use in modeling and predicting the structural and binding aspects of diverse peptides that interact with oncology targets MDM2/MDMX in comparison to both retrospective (pre-prediction) and prospective (post-prediction) data. In the retrospective study, CMDInventus modules (CMDpeptide, CMDboltzmann, CMDescore and CMDyscore) were used to accurately reproduce structural and binding data across multiple MDM2/MDMX data sets. In the prospective study, CMDescore, CMDyscore and CMDboltzmann were used to accurately predict binding affinities for an Ala-scan of the stapled α-helical peptide ATSP-7041. Remarkably, CMDboltzmann was used to accurately predict the results of a novel D-amino acid scan of ATSP-7041. Our investigations rigorously validate CMDInventus and support its utility for enabling peptide drug design
The Large-Scale Atomic and Molecular Gas in the Circinus Galaxy
We have used the ATCA and the SEST to map the large-scale atomic and
molecular gas in the nearby Circinus galaxy. The HI mosaic of Circinus exhibits
the warps in position angle and inclination revealed in the single-pointing
image, both of which appear to settle beyond the inner 30 kpc which was
previously imaged. The molecular gas has been mapped in both the CO
transitions, where we derive a total molecular gas mass of ~2e9 Mo. Within a
radius of 3 kpc, i.e. where CO was clearly detected, the molecular fraction
climbs steeply from ~0.7 to unity with proximity to the nucleus. Our HI mosaic
gives an atomic gas mass of ~6e9 Mo which is 70% of the fully mapped single
dish value. The total neutral gas mass to dynamical mass ratio is therefore 3%,
consistent with the SAS3 classification of Circinus. The high (molecular) gas
mass fraction found previously, only occurs close to the central ~0.5 kpc and
falls to < 10% within and outwith this region, allaying previous concerns
regarding the validity of applying the Galactic conversion ratio to Circinus.
The rotation curve, as traced by both the HI and CO, exhibits a steep dip at ~1
kpc, the edge of the atomic/molecular ring, within which the star-burst is
occurring. We find the atomic and molecular gases to trace different
kinematical features and believe that the fastest part of the sub-kpc ring
consists overwhelmingly of molecular gas. Beyond the inner kpc, the velocity
climbs to settle into a solid body rotation at >10 kpc. Most of the starlight
emanates from within this radius and so much of the dynamical mass, which
remains climbing to the limit of our data (>50 kpc), must be due to the dark
matter halo.Comment: 13 pages, MNRAS in pres
Aptamers as the Agent in Decontamination Assays (Apta-Decontamination Assays): From the Environment to the Potential Application In Vivo
The binding specificity and affinity of aptamers have long been harnessed as the key elements in the development of aptamer-based assays, particularly aptasensing application. One promising avenue that is currently explored based on the specificity and affinity of aptamers is the application of aptamers in the decontamination assays. Aptamers have been successfully harnessed as the decontamination agents to remove contaminants from the environment and to decontaminate infectious elements. The reversible denaturation property inherent in aptamers enables the repeated usage of aptamers, which can immensely save the cost of decontamination. Analogous to the point-of-care diagnostics, there is no doubt that aptamers can also be deployed in the point-of-care aptamer-based decontamination assay, whereby decontamination can be performed anywhere and anytime for instantaneous decision-making. It is also prophesied that aptamers can also serve more than as a decontaminant, probably as a tool to capture and kill hazardous elements, particularly pathogenic agents
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