Showing papers by "Sharda University published in 2011"

Nitric oxide: role in tumour biology and iNOS/NO-based anticancer therapies

Abstract: Purpose The diatomic radical nitric oxide (NO) has been the cause of intense debate with implication in carcinogenesis, tumour progression, invasion, angiogenesis and modulation of therapeutic responses. The tumour biology of NO is highly complex, and this review summarises the various protective and damaging mode of action of NO.

Science behind human saliva

Abstract: Saliva is a complex fluid, which influences oral health through specific and nonspecific physical and chemical properties. The importance of saliva in our everyday activities and the medicinal properties it possesses are often taken for granted. However, when disruptions in the quality or quantity of saliva do occur in an individual, it is likely that he or she will experience detrimental effects on oral and systemic health. Often head and neck radiotherapy has serious and detrimental side effects on the oral cavity including the loss of salivary gland function and a persistent complaint of a dry mouth (xerostomia). Thus, saliva has a myriad of beneficial functions that are essential to our well-being. Although saliva has been extensively investigated as a medium, few laboratories have studied saliva in the context of its role in maintaining oral and general health.

Contrasting Aerosol Trends Over South Asia During the Last Decade Based on MODIS Observations

Abstract: . Atmospheric aerosols over south Asia constitute a major environmental and climate issue. Thus, extensive land and cruise campaigns have been conducted over the area focusing on investigating the aerosol properties and climate implications. Except from the ground-based instrumentation, several studies dealt with analyzing the aerosol properties from space, focusing mainly on the spatial distribution of the aerosol optical depth (AOD) and possible feedbacks of aerosols on the monsoon system. However, except from some works using ground-based instrumentation or satellite observations over a specific region, there is lack of studies dealing with monitoring of the aerosol trend over south Asia. The present work analyzes the variations and trends in aerosol load over south Asia using Terra-MODIS AOD550 data in the period 2000–2009. Overall, an increasing trend of 10.17 % in AOD is found over whole south Asia, which exhibits large spatio-temporal variation. More specifically, the AOD550 increasing trend is more pronounced in winter, and especially over northern India. The present study shows an evidence of a decreasing AOD550 trend over the densely-populated Indo-Gangetic Plains (IGP) during the period April–September, which has never been reported before. This decreasing trend is not statistically significant and leads to an AOD change of −0.01 per year in June, when the dust activity is at its maximum. The AOD decrease seems to be attributed to weakness of dust activity in the northwest of India, closely associated with expansion of the vegetated areas and increase in precipitation over the Thar desert. Similarly, GOCART simulations over south Asia show a pronounced decreasing trend in dust AOD in accordance with MODIS. However, much more analysis and longer dataset are required for establishing this evidence.

Estimation of NOx Emissions from Delhi Using Car MAX-DOAS Observations and Comparison with OMI Satellite Data

Abstract: . We present the first Multi-Axis-(MAX-) DOAS observations in India performed during April 2010 and January 2011 in Delhi and nearby regions. The MAX-DOAS instrument was mounted on a car roof, which allowed us to perform measurements along individual driving routes. From car MAX-DOAS observations along closed circles around Delhi, together with information on wind speed and direction, the NO x emissions from the greater Delhi area were determined: our estimate of 4.4 × 10 25 molecules s −1 is found to be slightly lower than the corresponding emission estimates using the EDGAR emission inventory and substantially smaller compared to a recent study by Gurjar et al. (2004). We also determined NO x emissions from Delhi using OMI satellite observations on the same days. These emissions are slightly smaller than those from the car MAX-DOAS measurements. Finally the car MAX-DOAS observations were also used for the validation of simultaneous OMI satellite measurements of the tropospheric NO 2 VCD and found a good agreement of the spatial patterns. Concerning the absolute values, OMI data are, on average, higher than the car MAX-DOAS observations close to strong emission sources, and vice versa over less polluted regions. Our results indicate that OMI NO 2 VCDs are biased low over strongly polluted regions, probably caused by inadequate a-priori profiles used in the OMI satellite retrieval.

Extremely large anthropogenic-aerosol contribution to total aerosol load over the Bay of Bengal during winter season

Abstract: . Ship-borne observations of spectral aerosol optical depth (AOD) have been carried out over the entire Bay of Bengal (BoB) as part of the W-ICARB cruise campaign during the period 27 December 2008–30 January 2009. The results reveal a pronounced temporal and spatial variability in the optical characteristics of aerosols mainly due to anthropogenic emissions and their dispersion controlled by local meteorology. The highest aerosol amount, with mean AOD500>0.4, being even above 1.0 on specific days, is found close to the coastal regions in the western and northern parts of BoB. In these regions the Angstrom exponent is also found to be high (~1.2–1.25) indicating transport of strong anthropogenic emissions from continental regions, while very high AOD500 (0.39±0.07) and α380–870 values (1.27±0.09) are found over the eastern BoB. Except from the large α380–870 values, an indication of strong fine-mode dominance is also observed from the AOD curvature, which is negative in the vast majority of the cases, suggesting dominance of an anthropogenic-pollution aerosol type. On the other hand, clean maritime conditions are rather rare over the region, while the aerosol types are further examined through a classification scheme based on the relationship between α and dα. It was found that even for the same α values the fine-mode dominance is larger for higher AODs showing the strong continental influence over the marine environment of BoB. Furthermore, there is also an evidence of aerosol-size growth under more turbid conditions indicative of coagulation and/or humidification over specific BoB regions. The results obtained using OPAC model show significant fraction of soot aerosols (~6 %–8 %) over the eastern and northwestern BoB, while coarse-mode sea salt particles are found to dominate in the southern parts of BoB.

Present status of solid state photoelectrochemical solar cells and dye sensitized solar cells using PEO-based polymer electrolytes

Abstract: Due to energy crises in the future, much effort is being directed towards alternate sources. Solar energy is accepted as a novel substitute for conventional sources of energy. Out of the long list of various types of solar cells available on the market, solid state photoelectrochemical solar cells (SSPECs) and dye sensitized solar cells (DSSCs) are proposed as an alternative to costly crystalline solar cell. This review provides a common platform for SSPECs and DSSCs using polymer electrolyte, particularly on polyethylene oxide (PEO)-based polymer electrolytes. Due to numerous advantageous properties of PEO, it is frequently used as an electrolyte in both SSPECs as well as DSSCs. In DSSCs, so far high efficiency (more than 11%) has been obtained only by using volatile liquid electrolyte, which suffers many disadvantages, such as corrosion, leakage and evaporation. The PEO-based solid polymer proves its importance and could be used to solve the problems stated above. The recent developments in SSPECs and DSSCs using modified PEO electrolytes by adding nano size inorganic fillers, blending with low molecular weight polymers and ionic liquid (IL) are discussed in detail. The role of ionic liquid in modifying the electrical, structural and photoelectrochemical properties of PEO polymer electrolytes is also described.

Belimumab: First targeted biological treatment for systemic lupus erythematosus.

Abstract: Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder involving multiple organs and having diverse clinical manifestations. Among the rheumatic diseases, it has one of the highest mortality rates.[1] Its prevalence around the world ranges from 20 to 70 per 100,000 person-years.[2] Clinical features of SLE range from mild involvement of skin and joints to severe debilitating complications at later stages, such as infections and problems of renal, cardiovascular, and central nervous system, which are responsible for considerable morbidity and mortality. Being an autoimmune disease, SLE is characterized by the presence of antibodies against the self-antigens. The deposition of autoantibodies and immune complexes in the tissues leads to infl ammatory damage of various organ systems of the body.[3]

Experimental investigation of nonequilibrium capillarity effects: Fluid viscosity effects

Abstract: [1] Numerical models have been widely used to simulate multiphase flow in porous media for a variety of applications (e.g., NAPL migration in subsurface aquifers, carbon sequestration, agriculture, paper production, and petroleum reservoir development). The relationship between the difference in phase pressures and saturation is used as one of the important constitutive relationships in numerical models. Theoretical studies have suggested that this relationship should include a damping coefficient or capillarity coefficient () on the basis of thermodynamic considerations. A literature review suggests that the magnitude of this capillarity coefficient varies by over three orders of magnitude. While recent experimental studies have explored the effect of porous medium properties, effect of domain size, hysteresis, and the imposed boundary conditions on the magnitude of , there has been no experimental study investigating the impact of fluid viscosity on . This study reports on a series of primary drainage experiments conducted under both static and dynamic conditions in F70 silica sand. Fluid pairs used included water and silicone oil with two differing viscosities and slightly different densities (used as model nonaqueous phase liquids) in addition to air. Water saturation and both wetting and nonwetting phase pressures were measured in a custom-built aluminum column using EC-5 probes and tensiometers at three levels. Results show a strong dependence of the magnitude of the capillarity coefficient on effective fluid viscosity. This implies that consideration should be given for the inclusion of a capillarity coefficient in modeling tools used to simulate multiphase flow when fluids saturations are changing rapidly and when fluids have a large viscosity ratio.

Prevalence of radix entomolaris in mandibular permanent first molars: a study in a South Indian population

Abstract: Objective Anatomical racial variations are an acknowledged characteristic in permanent molars. Generally, mandibular first molars have 2 roots; however, the presence of a third root, radix entomolaris (RE), is a major anatomic variant among many population groups. This study evaluated the prevalence of permanent mandibular first molars featuring a distolingual root in a South Indian population. Study design Five hundred patients of South Indian origin possessing bilateral mandibular first molars were selected. The radiographs of these patients were evaluated under optimal conditions. A total of 1000 mandibular first molars were screened and the incidence of 3-rooted mandibular first molars and the correlation between left and right side occurrence and between either gender was recorded. Results The prevalence of 3-rooted mandibular first molars was 18.6% of the patients examined and 13.3% of the teeth examined. There was no statistically significant difference between genders or side of occurrence (P > .05). The bilateral incidence of a symmetric distribution was 43.01%. Conclusions RE is considered an Asiatic trait. The occurrence of this macrostructure in the South Indian population was 13.3%, which was lower than that of other patients of Mongoloid origin. The clinician must thoroughly examine the radiograph before initiation of endodontic therapy.

3D contaminant flow imaging in transparent granular porous media

Abstract: A physical model based on transparent soil technology is presented as a novel laboratory tool for ground contamination research. The model aims to reproduce both unsaturated and saturated conditions within a Spanish soil formation known as Miga sand. A soil surrogate made of a water-absorbing polymeric gel was employed. Multi-phase flow from a leaking underground storage tank was simulated in both saturated and unsaturated conditions in order to illustrate the usefulness of the technique in simulating a hypothetical spill of a light non-aqueous phase liquid under well-controlled test conditions. The plume observed was found to be spatially variable. The technique permits, for the first time, the simulation of specific grain size distributions in a transparent soil surrogate and visualization of plume development in three dimensions. Preliminary results indicate that the model is a potentially powerful tool for visualising pollutant transport in porous media. A brief description of the test setup, and a su...

Study of nano-CdS prepared in methanolic solution and polymer electrolyte matrix

Abstract: This present paper reports the study of cadmium sulphide (CdS) nanoparticles prepared under controlled condition in methanolic solution and also in polyethylene oxide polymer electrolyte matrix. The sulphurations of the cadmium salts were done in situ by a sodium sulphide solution. The concentration of the precursors has been controlled as detailed in the paper. All the preparation and characterization were carried out at room temperature. The nanoparticles were characterized by UV/Vis spectra in the range of 600 to 250 nm. The absence of bulk/micron size particles was noted in either of the system. The absorption edge near 510 nm indicates the presence of bulk CdS, whereas the presence of nanometer-sized particles is also reflected in low wavelength region. The sizes of the particles as well as particle distribution have been estimated using X-ray diffraction and scanning electron microscopy, respectively. A comparison in the spectra has been done for the sample prepared in either of the matrices. The particle size distribution in the polymeric matrix has been found to be more in comparison to that in the methanolic suspension. The polymer is reported to work as a binder, but not as a capping agent.

Influence of continental advection on aerosol characteristics over Bay of Bengal (BoB) in winter: results from W-ICARB cruise experiment

Abstract: . The transport of aerosols and pollutants from continental India to the adjoining oceanic areas is a major topic of concern and several experimental campaigns have been conducted over the region focusing on aerosol characteristics and their climate implications. The present study analyzes the spectral aerosol optical depth (AOD) variations over Bay of Bengal (BoB) during Winter-Integrated Campaign for Aerosols, gases and Radiation Budget (W-ICARB) from 27 December 2008 to 30 January 2009 and investigates the influence of the adjoining landmass to the marine aerosol field. High AOD500 values (>0.7) occurred over northern BoB due to outflow of aerosols and pollutants from the densely populated Indo-Gangetic Plains (IGP); low AOD500 (0.1–0.2) was observed in central and southern BoB, far away from the mainland. The Angstrom exponent "α" was observed to be high (>1.2) near coastal waters, indicating relative abundance of accumulation-mode continental aerosols. On the other hand, over southern BoB its values dropped below ~0.7. National Center for Environmental Prediction (NCEP) reanalysis data on winds at 850 and 700 hPa, along with air-mass trajectories calculated using Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model, suggested transport of continental aerosols from central and northern India over the BoB. On the other hand, when the ship was crossing the eastern BoB, the aerosol loading was strongly affected by air-masses originating from Southeast Asia, causing an increase in AOD and α. Biomass-burning episodes over the region played an important role in the observed aerosol properties. Terra/Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) AOD550 and cruise measured AOD550 showed good agreement (R2 = 0.86 and 0.77, respectively) over BoB, exhibiting similar AOD and α spatio-temporal variation.

Mechanism of charge recombination and IPCE in ZnO dye‐sensitized solar cells having I−/I and Br−/Br redox couple

Abstract: The influence of intensity and wavelength variation on the solar cell parameters of two different ZnO-based liquid state DSSCs named as Cell (A) ZnO/EosinY/LiI and Cell (B) ZnO/EosinY/LiBr was studied. It was found that Voc and Isc depend logarithmically and linearly on light flux, respectively, which indicates that light absorption and carrier diffusion do not limit the solar cell efficiency. The data was analyzed to ascertain the charge recombination mechanism between conduction band electrons and the electrolytes. The regeneration of dye due to I−/I3 and Br−/Br redox couple was examined by studying the wavelength dependence of IPCE. An estimation of series and shunt resistance is made using two methods: (i) different illumination method (ii) single I–V curve, for the two cells in order to understand the role of the electrolyte in controlling the solar cell parameters. Copyright © 2010 John Wiley & Sons, Ltd.

Aerosol optical properties over Delhi and Manora Peak during a rare dust event in early April 2005

Abstract: In this study we considered the optical aerosol parameters for two places in the IGP: Delhi 28.5° N, 77.2° E, 325 m asl and the high altitude station, Manora Peak 29.4° N, 79.5° E, 1958 m asl. Of the two selected stations, Delhi represents a highly populated and polluted location whereas Manora Peak represents a cleaner location in the central Himalayan region. During this dust storm event, the aerosol optical depth AOD was observed to increase considerably. The increment was 2.6–4.6 times over Delhi and 1.6–3.2 times over Manora Peak at wavelengths 380 and 1020 nm, respectively, with respect to the background values, whereas the Angstrom exponent α for both the stations remained close to zero during the event. The effect shows a considerable increase in direct dust radiative forcing in terms of a reduction in the broadband global irradiance for Delhi as well as for Manora Peak stations. The direct aerosol radiative forcing thus obtained was about 34% in the 400–1100 nm wavelength band at Manora Peak.

Robust Intuitionistic Fuzzy C-means clustering for linearly and nonlinearly separable data

Abstract: Intuitionistic Fuzzy C-means (IFCM) is a robust clustering method which is based upon intuitionistic fuzzy set theory. It uses Euclidean distance as a distance metric, hence can only cluster hyper spherically distributed data-sets in data space or in feature space. FCM and KFCM with a new distance measure (FCM-σ and KFCM-σ) can detect non-hyperspherical clusters in data space and feature space but they are sensitive to noise and produce inefficient results in the presence of noise. This paper present a robust Intuitionistic Fuzzy c-means(IFCM-σ) and a robust kernel Intutitionistic Fuzzy C-Means(KIFCM-σ) with a new distance metric that incorporates the distance variation in a cluster to regularize the distance between data point and the cluster centroid. Propose algorithms are the hybridization of IFCM, kernel function, and new distance metric in the data space and in the feature space which avoid various problems of IFCM and FCM-σ. Experiments are done using two-dimensional synthetic data-sets and noisy digital images, and results are compared with IFCM, KIFCM, FCM-σ and KFCM-σ. The results show that our proposed algorithms, especially KIFCM-σ are more effective.

Kernelized type-2 fuzzy c-means clustering algorithm in segmentation of noisy medical images

Abstract: The toughest challenges in medical diagnosis are uncertainty handling and noise. This paper presents a novel kernelized type-2 fuzzy c-means algorithm that is a generalization of conventional type-2 fuzzy c-means (T2FCM). Although T2FCM has proven effective for spherical data, it fails when the data structure of input patterns is non-spherical and complex. In this paper, we present a novel kernelized type-2 fuzzy c-means (KT2FCM) where type-2 fuzzy c-means is extended by adopting a kernel induced metric in the data space to replace the original Euclidean norm metric. Use of kernel function makes it possible to cluster data that is linearly non-separable in the original space into homogeneous groups in the transformed high dimensional space. From our experiments, we found that different kernel with different kernel widths lead to different clustering results. Thus a key point is to choose an appropriate value for the kernel width. Experimental are done using synthetic and real medical images (CT Scan and MR images) to show the effectiveness of method.

Correlation of glucose level among venous, gingival and finger-prick blood samples in diabetic patients

Abstract: It is essential for a dental surgeon or a periodontist to detect blood glucose level for patients whose signs and symptoms are suggestive of diabetes. Seventy patients in the age group of 40 to 80 years of either sex were selected for the study. The study population included patients with type 1 or type 2 diabetes mellitus. Venous blood was used as a control group, whereas gingival blood and finger-prick blood constituted the study groups I and II, respectively. The percentage deviations of gingival blood glucose level measurements and finger-prick blood glucose level measurements from the standard venous blood glucose level measurements were recorded, which showed that 72.86% of gingival and 68.57% of finger-prick blood glucose level measurements were found to be within ±15% of the standard venous blood glucose level measurements. All values exhibited significant correlations among each other, but correlations between glucose values obtained using venous and gingival blood samples were higher than the correlations between glucose values obtained using venous and finger-prick blood samples.

Malignant hyperthermia in the oral and maxillofacial surgery patient: an update

Abstract: Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle that presents as a hypermetabolic response to potent volatile anesthetic gases, such as halothane, sevoflurane, desflurane, the depolarizing muscle relaxant succinylcholine, and, rarely in humans, to stresses, such as vigorous exercise and heat. The syndrome is likely to be fatal if untreated. Early recognition of the signs of MH provides the clinical diagnostic clues. Diagnostic testing relies on assessing the in vitro contracture response of biopsied muscle to halothane, caffeine, and other drugs. Dantrolene sodium is a specific antagonist of the pathophysiologic changes of MH and should be available wherever general anesthesia is administered. The prevention and treatment of acute episodes of this disorder is of paramount importance to the oral and maxillofacial surgeon. The management of such patients in the oral and maxillofacial surgery setting and the recent advances in the field of MH are presented.

Solvent free reactions

Abstract: Reactions of nitrophenols have been studied in the eutectic melt of 8-hydroxyquinoline–benzoic acid, where it reacted with 8-hydroxyquinoline. The reactions were also carried out in solution. The reaction products obtained from both the methods were characterized by FT-IR, differential scanning calorimetry, X-ray diffraction technique and microstructural investigations. The reaction products obtained from eutectic melt were analyzed for C, H, N. The results showed that reaction products obtained from both the methods are same. An attempt has been made to propose the overall mechanism of the reaction in the eutectic melt.

Formation of blisters in kapton polymer by the effect of 1.25 MeV gamma irradiation

Abstract: The surface morphology, chemical, optical, and structural response of 1.25 MeV gamma rays irradiation at various doses ranging from 16 to 300 kGy on Kapton polymer samples were studied by using scanning electron microscope (SEM), Fourier Transform Infrared (FTIR), ultraviolet/visible absorption (UV/VIS) and X-ray diffraction (XRD). The morphology study shows the blisters formation on the Kapton polymer surface due to 1.25 MeV gamma rays irradiation at ambient temperature. This observation provides a basis for the quantitative evaluation of FTIR results obtained for thermally stable polymer on the chemical bond deterioration with increasing gamma irradiation. The blistering mechanism is correlated with the internal gases (CO, H2) released due to gamma radiation induced damages. The recorded UV–VIS spectrum shows a maximum absorption around the wavelength 540 nm. However, the nature of the spectra does not change due to gamma irradiation but a shift in absorption edge towards the higher wavelength side has been observed with increasing dose. The optical data shows an increase in the calculated band gap at the highest dose. The diffraction pattern of virgin sample shows that polymer is semicrystalline, but due to irradiation, a decrease in the peak intensity and FWHM and an increase in the crystallite size at the highest dose level of 300 kGy have been observed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

A robust method for image segmentation of noisy digital images

Abstract: A robust image segmentation algorithm called Extended Fuzzy C means (EFCM) is presented in this paper which preprocesses the image to reduce the noise effect and then apply FCM algorithm for image segmentation. Preprocessing of image is influenced by the direct eight neighborhood pixels of study pixel of an image under consideration. The advantages of the propose algorithm is: (1) Least execution time compared to other techniques. (2) It yields regions more homogeneous than those of other techniques. (3) It removes noisy spots and is less sensitive to noise. The propose technique is a powerful method for noisy image segmentation with least computation time and convergence rate compared to other image segmentation techniques.

Transparent Aquabeads To Visualize Flow In Porous Material

Abstract: Use of transparent synthetic soils to visualize flow problems has recently been developed with an optical system and digital image processing This paper proposes a new water-based transparent material called Aquabeads suitable for modeling natural soils As feasibility of using Aquabeads to visualize geoenvironmental problems, surfactant flushing tests were conducted to simulate Light Non-Aqueous Phase Liquid (LNAPL) ganglia transport through Aquabeads model with clay lens was performed The upward migration of motor oil ganglia during surfactant flushing was visualized Aquabeads possess advantages over available transparent synthetic soils ; water-based material, similar macroscopic hydraulic characteristics to natural soils, compatible with water- oil- selected surfactants-alcohols used for simulating multiphase flow Therefore, it is ideal for visualizing 2D flow, and soil contamination problems

Primary intraosseous carcinoma of the mandible: A case report with literature review.

Abstract: Primary intraosseous carcinoma (PIOC) is a rare tumor that has been infrequently reported. Some diagnostic criteria have been proposed to consider a lesion as PIOC: (1) absence of ulcer in the oral mucosa overlying the tumor, (2) absence of another primary tumor at the time of diagnosis and for at least 6 months during the follow-up, and (3) histological evidence of squamous cell carcinoma. The etiology is not clear, although odontogenic embryonic origin has been reported. Probably, PIOC derives from the remnants of odontogenic tissue, either the epithelial rests of Malassez or the remnants of the dental lamina.

Sequence Comparison and Phylogeny of Nucleotide Sequence of Coat Protein and Nucleic Acid Binding Protein of a Distinct Isolate of Shallot virus X from India

Abstract: Shallot virus X (ShVX), a type species in the genus Allexivirus of the family Alfaflexiviridae has been associated with shallot plants in India and other shallot growing countries like Russia, Germany, Netherland, and New Zealand. Coat protein (CP) and nucleic acid binding protein (NB) region of the virus was obtained by reverse transcriptase polymerase chain reaction from scales leaves of shallot bulbs. The partial cDNA contained two open reading frames encoding proteins of molecular weights of 28.66 and 14.18 kDa belonging to Flexi_CP super-family and viral NB super-family, respectively. The percent identity and phylogenetic analysis of amino acid sequences of CP and NB region of the virus associated with shallot indicated that it was a distinct isolate of ShVX.

Lightwand: a useful aid in faciomaxillary trauma

Abstract: Airway management in patients of faciomaxillary injury is of great concern to the anesthesiologist. Bag and mask ventilation and orotracheal intubation may be difficult with these patients. Recently, a middle aged, obese female presented in the emergency department after sustaining a blast injury, with laceration of the upper chest and left submandibular region. Laceration of the submandibular region was communicating with the intraoral space and the airway was filled with blood. The airway was secured with nasotracheal intubation aided by a lightwand, after failure with the Macintosh laryngoscope. This case report highlights the importance of the lightwand in intubating a patient with a bleeding airway and when the bright light glow of the lightwand gives sufficient direction toward the glottis for successful tracheal intubation.