43 research outputs found
M5-brane prongs, string soliton bound states and wall-crossing
We study abelian M5-brane field configurations representing BPS bound states
of self-dual string solitons whose locations correspond to the endlines of
M2-branes ending on the M5-branes. The BPS equations are obtained from
appropriate Bogomolny completion of the effective abelian low energy functional
with two transverse scalars, using two vectors representing the directions
along which these endline strings extend. Then we impose boundary conditions on
the scalars near the string soliton cores. This leads to a molecule-like
equilibrium structure of two non-parallel string solitons at fixed transverse
separations, with the M5-brane "prong" deformations comprising two "spikes",
each shaped like a ridge. The resulting picture becomes increasingly accurate
as one approaches the wall of marginal stability, on which these states decay.
There are various parallels with wall-crossing phenomena for string web
configurations obtained from D3-brane deformations.Comment: Latex, 44pgs, 3 figs, v2: further clarifications adde
Comparison of satellite image-based vegetation indices for extraction and mapping of litchi (Litchi Chinensis) cultivation area in Muzaffarpur district, Bihar, India
The aim of present study was to evaluate the suitability of various vegetation indices (VIs) to ex- tract litchi cultivation area in Muzaffarpur district of Bihar, India. VIs computed from the multispectral bands of Landsat satellites have been used in delineating litchi cultivation areas from other land cover cate- gories. In this study, ten selected VIs have been applied and compared their effectiveness in litchi cultiva- tion area mapping for years 2016 and 2020 respectively. The results showed that the Normalized Green Blue Difference Index (NGBDI) was found to be most appropriate for extracting and mapping the litchi cultivation area. The area statistics of litchi cultivation was validated and are in closer correspondence with the data reported by the state horticulture department. It was found that the area of Litchi cultivation field is increased from 10272.79 ha to 10400.63 ha during the period of 4 years (2016-2020) in the area under in- vestigation. The spatial distribution maps of litchi fruit represent a vital reference suitable for developing a regional action plan to promote its cultivation and benefits to farmers
MDCT angiography in evaluation of pediatric hemangiomas and peripheral vascular malformations
Background: To evaluate the role of MDCT angiography in peripheral hemangiomas and vascular malformations in pediatric patients.Methods: Total of 36 consecutive pediatric patients with clinically suspected peripheral hemangiomas and peripheral malformations were included in the study. MDCT angiography and doppler sonography was done for all patients. Final diagnosis was made by response to treatment and follow up. The statistical significance of various MDCT findings and post processing techniques was calculated. p value of <0.05 was considered significant.Results: Venous malformations were the most common. The MDCTA features which were significant in diagnosing venous malformations were phleboliths (p=0.039), peak enhancement in venous or delayed phase, absence of soft tissue mass, lacy tangle of vessels on maximum intensity projection and volume rendered images. Features significant in diagnosing arteriovenous malformations were tortuous arterial feeders, peak enhancement in arterial phase (0.0001), early draining vein (p=0.0001), venous phase wash out (p=0.0001), tense tangle of vessels on maximum intensity projection and volume rendered images (p=0.0003). Phleboliths (p=0.43) and venous or delayed phase peak enhancement (p=0.69) were overlapping features in congenital hemangiomas and venous malformations. Arterial phase enhancement (p=0.10) and early draining veins (p=0.39) were overlapping features in infantile proliferating hemangiomas and arteriovenous malformations. However, presence of soft tissue mass (p=0.0001) and lack of venous phase wash out (p=0.0003) were differentiating features for hemangiomas.Conclusions: MDCT angiography can be used as a highly accurate modality to diagnose hemangiomas and vascular malformations. It has an advantage over color Doppler in depicting entire extent of deep lesions
Imaging spectrum and prevalence of variant branching pattern of aortic arch
Background: Variant branching patterns of the aortic arch are not infrequent but are commonly under reported. This study was conducted to determine the spectrum of Variant branching pattern of aortic arch and their prevalence using contrast enhanced computed tomography (CECT) images of the cases from a tertiary care centre.Methods: Contrast enhanced computed tomography (CECT) images of aortic arch region from 1116(629 male and 487 female) cases from 18 to 85 years of age were examined retrospectively. The images were reviewed for normal and variant anatomy of aortic arch and the results were analyzed statistically.Results: Of 1116 patients, 878 (78.6%) cases showed normal and 238 (21.3%) cases had variant branching pattern of the aortic arch. The most common variation was the common origin of brachiocephalic trunk (BCT) and the left common carotid artery (LCCA) which was observed in 160 (14.3%) cases. In 8 (0.7%) cases, BCT and LCCA took origin from a single common trunk arising from the aortic arch. In 60(5.4%) cases, the left vertebral artery (LVA) originated directly from the aortic arch between the origin of the LCCA and left subclavian artery (SCA). 8 (0.7%) cases had aberrant right subclavian artery. Two (0.2%) cases showed right aortic arch.Conclusions: Interventional radiologists and surgeons should be well aware of variant anatomy of aortic arch. Contrast CT is a highly reliable imaging method for demonstrating anatomical features and variations of the arch
Optimization of state-of-the-art fuzzy-metaheuristic ANFIS-based machine learning models for flood susceptibility prediction mapping in the Middle Ganga Plain, India
CRediT authorship contribution statement: Dr. Aman Arora and Dr. Alireza Arabameri have conceptualized the study, prepared the dataset, and optimized the models. Dr. Manish Pandey has helped in writing the manuscript. Prof. Masood A. Siddiqui, Prof. U.K. Shukla, Prof. Dieu Tien Bui, Dr. Varun Narayan Mishra, and Dr. Anshuman Bhardwaj have helped in improving the manuscript at different stages of this work.Peer reviewedPostprin
Quantum effects, soft singularities and the fate of the universe in a braneworld cosmology
We examine a class of braneworld models in which the expanding universe
encounters a "quiescent" future singularity. At a quiescent singularity, the
energy density and pressure of the cosmic fluid as well as the Hubble parameter
remain finite while all derivatives of the Hubble parameter diverge (i.e.,
, , etc. ). Since the Kretschmann invariant
diverges () at the singularity, one expects
quantum effects to play an important role as the quiescent singularity is
approached. We explore the effects of vacuum polarization due to massless
conformally coupled fields near the singularity and show that these can either
cause the universe to recollapse or, else, lead to a softer singularity at
which , , and remain finite while {\dddot H} and
higher derivatives of the Hubble parameter diverge. An important aspect of the
quiescent singularity is that it is encountered in regions of low density,
which has obvious implications for a universe consisting of a cosmic web of
high and low density regions -- superclusters and voids. In addition to vacuum
polarization, the effects of quantum particle production of non-conformal
fields are also likely to be important. A preliminary examination shows that
intense particle production can lead to an accelerating universe whose Hubble
parameter shows oscillations about a constant value.Comment: 19 pages, 3 figures, text slightly improved and references added.
Accepted for publication in Classical and Quantum Gravit
Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries
Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely
Changes of glacier lakes using multi-temporal remote sensing data: A case study from India
The present study used the potential of Landsat multispectral data and ASTER-DEM data to identify the changes of glacier lakes in part of Chandra basin and surrounding of Himachal Pradesh of India from 1989 to 2013. The Barashigri, Chotashigri, Hamtahand Parvati glacier are the major glaciers within the area. The Landsat data of TM (1989 and 2009), ETM+ (2001) and OLI-TIRS (2013) sensors having different band combinations were analysed to monitor variation in the glacier lakes and area of glaciers and terminus whereas ASTER-DEM data was used for relief information. Glaciers terminus and glacial lakes were identified and mapped using false-colour composites (FCC) with band combinations of red, near-infrared (NIR) and shortwave infrared (SWIR), and a true-colour composite of red, green and NIR, of Landsat TM/ETM+ images and normalized difference water index (NDWI) methods. It is observed that the number of lakes in the study area increased by 18.69% during the past 34 years while it was increased from 68 in 1989 to 89 in 2013. During the analysis, it is also found that the snow and glacier covered area within this period is also reduced from 1,317.39 to 1,125.59 km2