We present spectral and timing properties of the newly discovered X-ray transient source, MAXI J1535-571, which is believed to be a Galactic X-ray binary containing a black hole candidate (BHC) as ...the primary object. Since its discovery on 2017 September 2, it has been monitored regularly in multi-wavelength bands by several satellites. We use archival data of the Swift (XRT and BAT) and MAXI (GSC) satellite instruments to study accretion flow dynamics of the source during the outburst. During its outburst, the source became very bright in the sky with a maximum observed flux of 5 Crab in the 2-10 keV GSC band. Similar to other transient BHCs, it also shows signatures of low-frequency quasi-periodic oscillations (QPOs) during the outburst. Spectral data of different instruments are fitted with the transonic flow, solution-based two-component advective flow model fits file to find the direct accretion flow parameters. The evolution of spectral states and their transitions are understood from the model-fitted physical flow parameters and nature of QPOs. We also estimate the probable mass of the black hole from our spectral analysis as 7.9-9.9 M or 8.9 1.0 M .
Galactic transient black hole candidate (BHC) MAXI J1535-571 was discovered on 2017 September 02 simultaneously by
MAXI
/GSC and
Swift
/BAT instruments. It has also been observed by India’s first ...multi-wavelength astronomy-mission satellite
AstroSat
, during the rising phase of its 2017-18 outburst. We make both the spectral and the temporal analysis of the source during 2017 September 12–17 using data of
AstroSat
’s Large Area X-ray Proportional Counter (LAXPC) in the energy range of 3–40 keV to infer the accretion flow properties of the source. Spectral analysis is done with the physical two-component advective flow (TCAF) solution-based
fits
file. From the nature of the variation of the TCAF model fitted physical flow parameters, we conclude and confirm that the source was in the intermediate spectral state during our analysis period. We observe sharp type-C quasi-periodic oscillations (QPOs) in the frequency range of
∼
1.75
–
2.81
Hz
. For a better understanding of the nature and evolution of these type-C QPOs, a dynamic study of the power density spectra is done. We also investigate the origin of these QPOs from the shock oscillation model. We find that non-satisfaction of Rankine-Hugoniot conditions for non-dissipative shocks and not their resonance oscillations is the cause of the observed type-C QPOs.
Abstract
The Galactic Center (GC) region hosts a variety of powerful astronomical sources and rare astrophysical processes that emit a large flux of nonthermal radiation. The inner 375 pc × 600 pc ...region, called the Central Molecular Zone, is home to the supermassive black hole Sagittarius A*, massive cloud complexes, and particle accelerators such as supernova remnants (SNRs). We present the results of our improved analysis of the very-high-energy gamma-ray emission above 2 TeV from the GC using 125 hr of data taken with the Very Energetic Radiation Imaging Telescope Array System imaging-atmospheric Cerenkov telescope between 2010 and 2018. The central source VER J1745–290, consistent with the position of Sagittarius A*, is detected at a significance of 38 standard deviations above the background level (38
σ
), and we report its spectrum and light curve. Its differential spectrum is consistent with a power law with exponential cutoff, with a spectral index of
, a flux normalization at 5.3 TeV of
TeV
−1
cm
−2
s
−1
, and cutoff energy of
TeV. We also present results on the diffuse emission near the GC, obtained by combining data from multiple regions along the GC ridge, which yield a cumulative significance of 9.5
σ
. The diffuse GC ridge spectrum is best fit by a power law with a hard index of 2.19 ± 0.20, showing no evidence of a cutoff up to 40 TeV. This strengthens the evidence for a potential accelerator of PeV cosmic rays being present in the GC. We also provide spectra of the other sources in our field of view with significant detections, composite SNR G0.9+0.1, and HESS J1746–285.
•Alternative fouling control methods are required for application of sewage treatment using ceramic NF.•This paper introduces reaction based precoat as fouling control method for ceramic NF ...membranes.•Reaction based precoat method enables detachment of fouling layer from membrane surface.•The reaction based precoat method was compared with hydraulic backwash and forward flush.•Reaction based precoat method has potential for removal of fouling from ceramic NF treating sewage.
Using ceramic nanofiltration membranes for treatment of municipal sewage is upcoming. However, the knowledge on fouling control methods for this application are very limited. The most commonly used fouling control method, chemical cleaning, has disadvantages. Chemical cleaning negatively impacts (i) the glass seal layer of tubular ceramic nanofiltration membranes and (ii) the environment, especially when using sodium hypochlorite for removal of organic fouling. Therefore, the use of chemical cleaning should be limited as much as possible. In this research, first, the well-known fouling control methods for polymeric micro- and ultrafiltration membranes, were studied on ceramic nanofiltration membranes: hydraulic backwash and forward flush. Second, a precoat method was combined with a chemical reaction to aid the detachment of the formed cake layer. In this method, a precoat layer was filtered atop of the membrane surface before the start of filtration. The precoat layer then acts as a barrier between the foulants and the membrane surface. After filtration, the precoat layer reacts with the cleaning reagent underneath the fouling layer to enable fast removal of fouling. Results showed that hydraulic backwash was not effective to be used for this type of membranes. Forward flush was able to maintain a higher flux but the relative production downtime was high. Reaction based precoat was most effective in maintaining a high flux and resulted in the highest net water production. Two reaction based precoat methods were tested of which the reaction of calcium carbonate with citric acid was more effective than a Fenton reaction.
•An extension to the MWCO method was introduced to quantify defects in membranes.•Defects are frequently detected in the studied commercial ceramic membranes.•Quality of pristine ceramic tight ultra- ...and nanofiltration membranes varied within one batch.•Long-term exposure to NaClO damages glass seal layer at edges of tubular membranes.
One of the perceived benefits of ceramic membranes is their robustness, which makes them suitable for treating high organic load waste streams. In particular, ceramic tight ultrafiltration (tUF) and nanofiltration (NF) form an important barrier against small colloids and organic molecules. In order to achieve this barrier, the quality of the membranes should be uncompromised.
An extension on a commonly used size exclusion method was developed in order to quantify defects in membranes and calculate the MWCO accurately excluding the defects. This approach gives a better representation of the membrane quality than the original method. The quality of a broad range of commercial ceramic membranes was investigated by determining the (i) hydraulic permeability, (ii) molecular weight cut-off, and (iii) quantitative defects. Several membranes – both tubular and disc membranes, selected from various suppliers – were tested to investigate their variability. Furthermore, the robustness of tubular NF membranes was studied by monitoring the effect of long-term exposure to sodium hypochlorite, which is commonly used to mitigate organic fouling.
The results showed that batches of both tubular and disc membranes of different pore size and suppliers included membranes with defects. Furthermore, the long-term treatment of tubular ceramic membranes with sodium hypochlorite negatively affected, beyond expectation, the quality of the membranes. The separation layer in these membranes was not notably compromised by sodium hypochlorite exposure, but the end seal layer was damaged.
The Compton Spectrometer and Imager (COSI), formerly known as the Nuclear Compton Telescope (NCT), is a balloon-borne soft gamma-ray telescope (0.2–5MeV) designed to study astrophysical sources of ...nuclear-line emission and gamma-ray polarization. The heart of COSI is a compact array of cross-strip germanium detectors (GeDs), providing excellent spectral resolution (~0.2–1%) and the capability to track individual photon interactions with full 3D position resolution to 1.6mm3. COSI is built upon considerable heritage from the previous NCT balloon instrument, which has flown successfully on two conventional balloon flights to date. The Crab Nebula was detected at a significance of 6σ in the second flight, which is the first reported detection of an astrophysical source by a compact Compton telescope. COSI has been upgraded from the previous NCT instrument to be an Ultra Long Duration Balloon (ULDB) payload, utilizing a new detector configuration optimized for polarization sensitivity and employing a mechanical cryocooler to remove consumables (LN2) for ULDB flights. The instrument is being integrated for a ULDB flight in December 2014 from Antarctica on a superpressure balloon. Here we will present the redesign of the instrument and our current progress in preparing for the flight.
To explore the magnetic resonance imaging (MRI) differences between pancreatic neuroendocrine tumour grade 3 (pNET-G3) and pancreatic neuroendocrine carcinoma grade 3 (pNEC-G3).
Between 2009 and ...2019, 31 patients underwent pNEN-G3 resection with preoperative MRI in two local hospitals in China. The 31 patients were assigned to a pNET-G3 group (n=13) or a pNEC-G3 group (n=18). The MRI findings between the groups were compared.
There was no statistically significant difference between the two groups in lesion size, clinical characteristics, or laboratory indexes. The lesions showed high or slightly higher signal on diffusion-weighted imaging and decreased apparent diffusion coefficient (ADC) values, which differed between the two groups (p=0.013). The difference between the groups regarding positive enhancement integral, arterial phase and portal phase signal enhancement ratio were statistically significant; however, the delayed phase signal enhancement ratio was not significantly different.
pNET-G3 and pNEC-G3 showed different characteristics on MRI. In particular, the ADC value and dynamic enhanced imaging could have an important role in distinguishing between the two.
•The first use of MRI to distinguish between pNET-G3 and pNEC-G3.•Dynamic enhanced MRI and DWI can be used for preliminary preoperative classification.•Which also can guide the clinical development of a more complete treatment plan.
Abstract
The Breakthrough Listen Initiative is conducting a program using multiple telescopes around the world to search for “technosignatures”: artificial transmitters of extraterrestrial origin ...from beyond our solar system. The Very Energetic Radiation Imaging Telescope Array System (VERITAS) Collaboration joined this program in 2018 and provides the capability to search for one particular technosignature: optical pulses of a few nanoseconds in duration detectable over interstellar distances. We report here on the analysis and results of dedicated VERITAS observations of Breakthrough Listen targets conducted in 2019 and 2020 and of archival VERITAS data collected since 2012. Thirty hours of dedicated observations of 136 targets and 249 archival observations of 140 targets were analyzed and did not reveal any signals consistent with a technosignature. The results are used to place limits on the fraction of stars hosting transmitting civilizations. We also discuss the minimum pulse sensitivity of our observations and present VERITAS observations of CALIOP: a space-based pulsed laser on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations. The detection of these pulses with VERITAS, using the analysis techniques developed for our technosignature search, allows a test of our analysis efficiency and serves as an important proof of principle.
The aim of this study was to identify dysregulated pathways for the diagnosis and treatment of dilated cardiomyopathy (DCM) using pathway interaction network analysis. Methods: Transcriptome data of ...DCM, protein-protein interaction (PPI) data, and pathway data were recruited and preprocessed. Then, the pathway interaction network was constructed based on the gene expression analysis and gene co-expression analysis. Meanwhile, pathway activity analysis was performed, and the pathway with the greatest activity change was defined as the seed pathway. Staring from the seed pathway, the dysregulated pathways that could serve as diagnostic biomarker was extracted from the pathway interaction network using support vector machines. Results: Combining gene expression and co-expression data, we constructed the pathway interaction network, covering 4175 pathway interactions. Via pathway activity analysis, cap-dependent translation initiation with the greatest activity change was defined as the seed pathway. Staring from cap-dependent translation initiation, a total of 21 dysregulated pathways were obtained, which could discriminate DCM samples from controls with the area under the curve value of 0.95. Conclusion: A pathway interaction network was implemented to identify dysrgulated pathways that can best discriminate DCM samples from controls. We identified a total of 21 dysregulated pathways in DCM, which can serve as diagnostic biomarkers for DCM.
Abstract
We report on the search for very-high-energy gamma-ray emission from the regions around three nearby supersonic pulsars (PSR B0355+54, PSR J0357+3205, and PSR J1740+1000) that exhibit long ...X-ray tails. To date there is no clear detection of TeV emission from any pulsar tail that is prominent in X-ray or radio. We provide upper limits on the TeV flux, and luminosity, and also compare these limits with other pulsar wind nebulae detected in X-rays and the tail emission model predictions. We find that at least one of the three tails is likely to be detected in observations that are a factor of 2–3 more sensitive. The analysis presented here also has implications for deriving the properties of pulsar tails, for those pulsars whose tails could be detected in TeV.
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