1,420 research outputs found
Efficient dynamical downscaling of general circulation models using continuous data assimilation
Continuous data assimilation (CDA) is successfully implemented for the first
time for efficient dynamical downscaling of a global atmospheric reanalysis. A
comparison of the performance of CDA with the standard grid and spectral
nudging techniques for representing long- and short-scale features in the
downscaled fields using the Weather Research and Forecast (WRF) model is
further presented and analyzed. The WRF model is configured at 25km horizontal
resolution and is driven by 250km initial and boundary conditions from
NCEP/NCAR reanalysis fields. Downscaling experiments are performed over a
one-month period in January, 2016. The similarity metric is used to evaluate
the performance of the downscaling methods for large and small scales.
Similarity results are compared for the outputs of the WRF model with different
downscaling techniques, NCEP reanalysis, and Final Analysis. Both spectral
nudging and CDA describe better the small-scale features compared to grid
nudging. The choice of the wave number is critical in spectral nudging;
increasing the number of retained frequencies generally produced better
small-scale features, but only up to a certain threshold after which its
solution gradually became closer to grid nudging. CDA maintains the balance of
the large- and small-scale features similar to that of the best simulation
achieved by the best spectral nudging configuration, without the need of a
spectral decomposition. The different downscaled atmospheric variables,
including rainfall distribution, with CDA is most consistent with the
observations. The Brier skill score values further indicate that the added
value of CDA is distributed over the entire model domain. The overall results
clearly suggest that CDA provides an efficient new approach for dynamical
downscaling by maintaining better balance between the global model and the
downscaled fields
Peripheral and central analgesic activity evaluation of ethanolic extract of Vitex Negundo flowers in experimental animals
Background: Vitex negundo Linn (Family: Verbenaceae), locally known as ‘Nirgundi’ an important medicinal plant is a woody, aromatic shrub growing to a small tree. It commonly bears tri- or penta-foliate leaves on quadrangular branches, which give rise to bluish-purple coloured flowers in branched tomentose cymes. It has been claimed to possess analgesic activity apart from many medicinal properties. The aim of the present study was to evaluate both the peripheral and central analgesic activity of ethanolic extract of Vitex negundo flowers (EEVNF) in experimental animals.Methods: Acute toxicity test was done following the Organization of Economic Cooperation and Development guidelines. EEVNF (100mg/kg, 200mg/kg, and 400 mg/kg body weight [b.w.] p.o) was evaluated for peripheral analgesic activity by the acetic acid (0.7%) induced writhing test and central analgesic activity by the tail flick method respectively using aspirin (100mg/kg b.w. and 300mg/kg b.w.) as the standard drug.Results: EEVNF significantly decreased the number of writhing in writhing test at all the doses (p<0.001) and increased the reaction time in tail-flick method (p<0.001) at all the doses when compared to control. EEVNF in the dosage of 400mg/kg b.w. produced analgesic effects which was comparable with that of the standard drug aspirin at dose 100mg/kg b.w in writhing test and produced greater analgesic activity than that of standard drug aspirin at dose 300mg/kg b.w in tail flick method.Conclusions: EEVNF has significant peripheral and central analgesic activity
Improved controller design for two-input-two-output (TITO) unstable processes
Controller design for unstable processes is relatively difficult when compared to stable processes. The complexity increases further for multivariable unstable processes. In this work, simplified tuning rules are proposed to design PID controller for unstable multivariable processes. Decouplers are applied to make the loops independent and diagonal elements of equivalent transfer function are used to design controllers. For this, the decoupler design procedure proposed by Hazarika and Chidambaram [10] is used. Two theoretical examples of TITO unstable processes with time delays are considered for simulation. Comparative analysis has been carried out with the recently reported methods in the literature and observed that the proposed method provides improved closed loop performances. Robustness studies are also carried out with various perturbations in the processes
KC Two-Way Clustering Algorithms For Multi-Child Semantic Maps In Image Mining
Image mining is now a thriving and expanding field of computer science research. Image mining is linked to the advancement of data mining in image preparation. Image mining is used to extract hidden information and in other situations where the photos do not clearly describe the situation. Image mining combines machine learning, data handling, application autonomy, and image preparation concepts. Semantic maps are used to visualize image data stored in image databases. We recommend using Multi-Child Semantic Maps to build semantic maps which fully display the image. In this study, we propose two path clustering on Multi-Child Semantic Maps (MCSM) using the K-C Means Clustering Algorithm, also known as the MCSMK-C algorithm. This algorithm causes image clustering and instructs the mining system to look at the image's top area. When mining, the MCSMK-C algorithm considers the X and Y coordinates. The system looks for groups by examining each object's territory in the database, and it saves a region if it contains more objects than the required number
Marine invertebrate metabolites with anticancer activities: solutions to the "supply problem"
Marine invertebrates provide a rich source of metabolites with anticancer activities and several marine-derived agents have been approved for the treatment of cancer. However, the limited supply of promising anticancer metabolites from their natural sources is a major hurdle to their preclinical and clinical development. Thus, the lack of a sustainable large-scale supply has been an important challenge facing chemists and biologists involved in marine-based drug discovery. In the current review we describe the main strategies aimed to overcome the supply problem. These include: marine invertebrate aquaculture, invertebrate and symbiont cell culture, culture-independent strategies, total chemical synthesis, semi-synthesis, and a number of hybrid strategies. We provide examples illustrating the application of these strategies for the supply of marine invertebrate-derived anticancer agents. Finally, we encourage the scientific community to develop scalable methods to obtain selected metabolites, which in the authors' opinion should be pursued due to their most promising anticancer activities
A Rare Case of Lung Hypoplasia, Cardiac Anomalies and Ovarian Tumour in a Patient with MRKH Syndrome
Hypoplasia of the lung is an uncommon congenital abnormality of the respiratory system in contrast to Pulmonary agenesis. Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome is the congenital absence of the upper two-thirds of the vagina and uterus with normal secondary sexual characteristics, ovary, and normal karyotype. Here we describe a case of left lung hypoplasia and congenital cardiac malformations with MRKH syndrome and Leiomyoma of the ovary. A 31-year-old female presented with cough with expectoration, left side chest pain and breathlessness for four years to Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER). She was evaluated for amenorrhea and diagnosed as MRKH syndrome and the patient underwent right side oophorectomy for right ovarian torsion with a tumour. Computed Tomography Pulmonary Angiogram (CTPA) and fiberoptic endoscopy were suggestive of left lung hypoplasia, and the patient was advised symptomatic treatment for lung hypoplasia and planned for vaginoplasty.
Keywords: Pulmonary hypoplasia, Infertility, Mullerian aplasia, congenital bronchiectasis, Left-sided superior vena cava, ovarian Leiomyoma
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