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Simulation Analysis on Applicability of Meta Material and PBG Based mm-Wave Planar Antenna for Advanced Cellular Technologies  [PDF]
Smrity Dwivedi
Open Journal of Antennas and Propagation (OJAPr) , 2017, DOI: 10.4236/ojapr.2017.51003
Abstract: Metamaterials have got a unique identification in the field of electromagnetic. Left handed metamaterials have been recognized through its working at high frequencies with larger bandwidth in antenna design. The author has proposed a multi substrates LH metamaterials with an array of split triangular antennas for wideband as well as for larger bandwidth. FR4 is being used at frequency 42 - 26 GHz with thickness of 3 mm for substrate and matching circuit is inserted to get high gain with minimum reflections. The number of rods in PBG is 100, which is found to get high return losses and ideal behavior of VSWR. Obtained results have been in good agreement such as S11 is approximately 30 dB, VSWR 1.8 dB and the bandwidth enhancement is 2 GHz at frequency 5 GHz. All results are plotted using commercial software CST microwave studio (Version 2012) and MATLAB.
Design of Wideband PBG Antenna for New Generation Communication Systems through Simulation  [PDF]
Smrity Dwivedi
Open Journal of Antennas and Propagation (OJAPr) , 2017, DOI: 10.4236/ojapr.2017.54013
Abstract:
In modern wireless communication system, demand of high bandwidth antennas with low cost are increased. In proposed paper, these requirements have been fully justified by using PBG based wideband antenna. Although, metamaterial is one more option to build this idea, sometimes, negative permittivity or negative permeability or both does not permit to allow easy fabrication and maintaining low cost. An antenna with several periodic rods and organic magnetic materials substrate made it possible to enhance the bandwidth and think off using it for 5G communication systems. Proposed antenna is designed and fabricated for frequency range of 40 GHz - 50 GHz, and 12 × 9 periodic rods with substrate having organic magnetic materials property. Antenna is designed and analyzed using commercial simulation software CST microwave studio (CST STUDIO SUITE 2014) and measured for return loss and VSWR for fabricated design. Obtained results meet the requirement of wider bandwidth of 1.5 - 2 GHz and return loss, ?35 dB, and directivity is 61 dBi with efficiency of 61%.
Role of Multidetector CT in Evaluation of Polytrauma Patients  [PDF]
Amit Nandan Dhar Dwivedi
Open Journal of Emergency Medicine (OJEM) , 2014, DOI: 10.4236/ojem.2014.23009
Abstract:

Trauma is the leading cause of death in age group less than 45 years. In trauma, time is one of the most crucial factors in predicting prognosis. Outcomes are greatly improved when critical interventions are provided within the golden hour following injury. Whole body multidetector computerised tomography (WBMDCT) can decrease this critical time and increase survival. Emergency CT plays a major role in diagnostic workflow in the evaluation of patients with polytrauma. MDCT scanners are widely used because they rapidly produce high-resolution scans of large areas, offering short examination times for multiple body regions under emergency conditions. Such examinations most often include the head, cervical spine, and thorax to pelvis. Role of MDCT in head trauma remains unparalleled for reasons like its widespread availability and capability to reveal skull fractures, primarily because it is a fast and efficient method to triage the patients with treatable conditions mandating urgent surgical intervention such as extra axial hematomas, mass effect, herniations of brain, hydrocephalus, and midline shift and hence preventing secondary brain injury. MDCT angiography is an important tool to screen patients with suspected vascular injury.

Distribution and Association of Arbuscular Mycorrhizal Fungi in Different Cultivars of Wheat from Lalganj Pratapgarh District of Utter Pradesh, India  [PDF]
O. P. Dwivedi
Advances in Bioscience and Biotechnology (ABB) , 2015, DOI: 10.4236/abb.2015.65034
Abstract: Arbuscular mycorrhizal fungi are key components of soil micro-flora and obviously interact with other microorganisms in the rhizosphere which is the zone of influence of plant roots on microbial populations and other soil constituents. Keeping in view the importance of AM fungi, the present study was undertaken for assessing the AM fungal spore population dynamics in the rhizosphere soil and its colonization in rhizosphere soils in relation to soil physico-chemical factors. Present study represents an attempt to establish the qualitative and quantitative distribution of AM fungal species in rhizosphere soils of wheat. Thirteen different wheat cultivars collected from four different sites of Lalganj Pratapgarh (U.P.), India were examined for the AM infection. All the wheat cultivars were found to be infected with arbuscular mycorrhizae. However, their population in rhizosphere and root infection varied to a considerable extent from species to species. The maximum spore population and highest percentage of root colonization were found with the rhizosphere soil of cultivars Ankur Kedar.
Statistical models for predicting number of involved nodes in breast cancer patients  [PDF]
Alok Kumar Dwivedi, Sada Nand Dwivedi, Suryanarayana Deo, Rakesh Shukla
Health (Health) , 2010, DOI: 10.4236/health.2010.27098
Abstract: Clinicians need to predict the number of involved nodes in breast cancer patients in order to ascertain severity, prognosis, and design subsequent treatment. The distribution of involved nodes often displays over-dispersion—a larger variability than expected. Until now, the negative binomial model has been used to describe this distribution assuming that over-dispersion is only due to unobserved heterogeneity. The distribution of involved nodes contains a large proportion of excess zeros (negative nodes), which can lead to over-dispersion. In this situation, alternative models may better account for over-dispersion due to excess zeros. This study examines data from 1152 patients who underwent axillary dissections in a tertiary hospital in India during January 1993-January 2005. We fit and compare various count models to test model abilities to predict the number of involved nodes. We also argue for using zero inflated models in such populations where all the excess zeros come from those who have at some risk of the outcome of interest. The negative binomial regression model fits the data better than the Poisson, zero hurdle/inflated Poisson regression models. However, zero hurdle/inflated negative binomial regression models predicted the number of involved nodes much more accurately than the negative binomial model. This suggests that the number of involved nodes displays excess variability not only due to unobserved heterogeneity but also due to excess negative nodes in the data set. In this analysis, only skin changes and primary site were associated with negative nodes whereas parity, skin changes, primary site and size of tumor were associated with a greater number of involved nodes. In case of near equal performances, the zero inflated negative binomial model should be preferred over the hurdle model in describing the nodal frequency because it provides an estimate of negative nodes that are at “high-risk” of nodal involvement.
Determinants of infant mortality in rural India: A three-level model  [PDF]
Sada Nand Dwivedi, Shahina Begum, Alok Kumar Dwivedi, Arvind Pandey
Health (Health) , 2013, DOI: 10.4236/health.2013.511235
Abstract: Taking into account the hierarchical structure of the data, through two-level analysis on infant mortality available under second round of National family Health Survey, the same group of authors recently reported determinants of infant mortality while examining possible changes in results under traditional regression analysis that ignores hierarchical structure of data. They reported that the community (e.g., state) level characteristics still have a major role regarding infant mortality in India. For better epidemiological understanding, the present study is to assess determinants of infant mortality in rural India, where three level considerations were possible. The results indicate that even after consideration of these covariates, variation in infant mortality remains significant not only between States but also between Districts. Further, as an additional observation, the probability of infant mortality is still high in rural areas of districts having health facility beyond three kilometers than their counterparts.
Study of Intermolecular Interactions in Liquid Crystals: Para-butyl-p’-cyano-biphenyl  [PDF]
K. K. Dwivedi, M. K. Dwivedi, S. N. Tiwari
Journal of Crystallization Process and Technology (JCPT) , 2014, DOI: 10.4236/jcpt.2014.41005
Abstract:

Various characteristics of mesomorphism can be explained using intermolecular interactions between a pair of liquid crystalline molecules. The intermolecular interactions have been calculated considering multipole-multicentere expansion method and modified by second order perturbation treatments. For calculation of multipole i.e. charge, dipole, etc. at each atomic center of molecules, para-butyl-p’-cyano-biphenyl, GAMESS, an ab initio program, with 6-31G* basis set has been used. The stacking, in-plane and terminal interaction energies explain the liquid crystalline behaviour of the system.

An epidemiological study on delay in treatment initiation of cancer patients  [PDF]
Alok Kumar Dwivedi, Sada Nand Dwivedi, Suryanarayana Deo, Rakesh Shukla, Arvind Pandey, Durgesh Kumar Dwivedi
Health (Health) , 2012, DOI: 10.4236/health.2012.42012
Abstract: Early diagnosis and timely initiation of treatment of cancer patients may improve survival and quality of life. Various measures of delay can be made during diagnosis and treatment initiation. Most of the studies were based on single type of cancer with different definitions and measurements of delay in diagnosis and treatment. Thus, it has been difficult to synthesize results and generalize to other types of cancer. The study proposes to measure total duration between onsets of symptom to start of treatment into three components, namely primary, secondary and tertiary delays. Primary delay is defined as onset of symptoms to contacting the first medical person, secondary delay is from first medical contact to confirmed diagnosis, and tertiary delay is from confirmed diagnosis to treatment initiation. The aim of this study is to determine factors associated with primary, secondary and tertiary delays in cancer patients. This study was planned as a cross-sectional study. Data was collected from patients admitted to the surgical wards of Department of Surgical Oncology, Institute Rotary Cancer Hospital, New Delhi during 2006-2007. Gamma regression and quantile regressions at 25th, 50th and 75th percentile of each of the delays were used to determine related factors. A total of 403 patients were included in the analysis. The median tertiary delay was found almost two folds (59; Interquartile range: 26 - 101 days) than the primary and secondary delays. Extremity cancer patients had longest primary, secondary and tertiary delays. Shortest primary, secondary and tertiary delays were observed for gastrointestinal cancer, breast and genitourinary cancer respectively. There is an urgent need and scope to reduce delay at each level primary, secondary and tertiary delay. Intervention studies are needed through information, education and communication/screening programs to reduce the diagnostic and treatment delays in cancer patients.
Brain-derived neurotrophic factor: role in depression and suicide
Yogesh Dwivedi
Neuropsychiatric Disease and Treatment , 2009, DOI: http://dx.doi.org/10.2147/NDT.S5700
Abstract: rain-derived neurotrophic factor: role in depression and suicide Review (10527) Total Article Views Authors: Yogesh Dwivedi Published Date August 2009 Volume 2009:5 Pages 433 - 449 DOI: http://dx.doi.org/10.2147/NDT.S5700 Yogesh Dwivedi Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA Abstract: Depression and suicidal behavior have recently been shown to be associated with disturbances in structural and synaptic plasticity. Brain-derived neurotrophic factor (BDNF), one of the major neurotrophic factors, plays an important role in the maintenance and survival of neurons and in synaptic plasticity. Several lines of evidence suggest that BDNF is involved in depression, such that the expression of BDNF is decreased in depressed patients. In addition, antidepressants up-regulate the expression of BDNF. This has led to the proposal of the “neurotrophin hypothesis of depression”. Increasing evidence demonstrates that suicidal behavior is also associated with lower expression of BDNF, which may be independent from depression. Recent genetic studies also support a link of BDNF to depression/suicidal behavior. Not only BDNF, but abnormalities in its cognate receptor tropomycin receptor kinase B (TrkB) and its splice variant (TrkB.T1) have also been reported in depressed/suicidal patients. It has been suggested that epigenetic modulation of the Bdnf and Trkb genes may contribute to their altered expression and functioning. More recently, impairment in the functioning of pan75 neurotrophin receptor has been reported in suicide brain specimens. pan75 neurotrophin receptor is a low-affinity neurotrophin receptor that, when expressed in conjunction with low availability of neurotropins/Trks, induces apoptosis. Overall, these studies suggest the possibility that BDNF and its mediated signaling may participate in the pathophysiology of depression and suicidal behavior. This review focuses on the critical evidence demonstrating the involvement of BDNF in depression and suicide.
An Ultra Wideband Wide Beam Strip line Fed Taper Slot Antenna for Active Phased Array Jammer
Gaurav Dwivedi
International Journal of Engineering and Advanced Technology , 2012,
Abstract: Multi octave bandwidth, wide scanning angle, small interelement spacing and mutual coupling between elements are some of the requirements of Active Phased Array (APA) used for EW Jammer applications. Taper Slot Antenna (TSA) represents a class of antenna elements which is capable enough to meet all these requirements. Keeping the properties of TSA in mind, a Strip line fed Taper Slot Antenna (TSA) has been designed and fabricated to serve as an Antenna element over a large bandwidth from 6 to 18 GHz for an Active Phased Array (APA). This Antenna Element exhibits some attractive features like wide beam width over a wide bandwidth, Gain for a high ERP, compactness and less mutual coupling. The simulated as well as the measured radiation pattern and VSWR have been presented and discussed in this paper. The Antenna element has been designed and optimized in CST Microwave.
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