Stability and multi-parametric Hopf bifurcation analyses of viral infection model with time delay

Ever since HIV was first diagnosed in human, a great number of scientific works have been undertaken to explore the biological mechanisms involved in the infection and progression of the disease. This paper deals with stability and bifurcation analyses of mathematical model that represents the dynamics of HIV infection of thymus. The existence and stability of the equilibria are investigated. The model is described by a system of delay differential equations with logistic growth term, cure rate and discrete type of time delay. Choosing the time delay as a bifurcation parameter, the analysis is mainly focused on the Hopf bifurcation problem to predict the existence of a limit cycle bifurcating from the infected steady state. Further, using center manifold theory and normal form method we derive explicit formulae to determine the stability and direction of the limit cycles. Moreover the mitosis rate r also plays a vital role in the model, so we fix it as second bifurcation parameter in the incidence of viral infection. Our analysis shows that, while both the bifurcation parameters can destabilize the equilibrium E* and cause limit cycles. Numerical simulations are performed to investigate the qualitative behaviors of the inherent model.

Intra cranial complications of tuberculous otitis media

Tuberculosis is one of the most common infections in the world. It is seen that tuberculous otitis media (TOM) is almost secondary to pulmonary tuberculosis. In this review we have tried to deal with all the aspects of the intra cranial complications of TOM such as tuberculoma, otitic hydrocephalus, brain abscess and tuberculous meningitis. The aspects covered in this review are the pathology, clinical features, and investigations of the intra cranial manifestations.

Rhinosporidiosis and the pond

Rhinosporidiosis is a fungal disease caused by the organism Rhinosporidum seeberi. The life cycle and mode of infection are vague, and there are many hypothesis on it. Its prevalence in the world is unique as it is only limited to certain regions like India, Pakistan and Sri Lanka. We have tried to correlate the various factors, which will probably be associated with this pattern of prevalence of the disease. We have included factors like community practices, climatic conditions, rain fall pattern, water physiochemical properties, zoonotic and the aquatic organism composition in the specified regions. Thus, it serves as a wholesome idea of why the disease must only be prevalent in certain parts of the world.

Characterization of Znq+–imidazole (q = 0, 1, 2) organometallic complexes: DFT methods vs. standard and explicitly correlated post-Hartree–Fock methods

Benchmarking DFts for the characterization of the Zn^q+–imidazole (q= 0, 1, 2) complexes.

Things you don′t learn in medical school: Caduceus

It is a known fact that every symbol has a unique meaning. In that case what does this unique symbol, Caduceus, which is used, in various forms and modifications, by many medical organizations mean? Is it just a custom or does it have a deeper meaning? The story of this medical symbol started way back in 1400 BC, travelled through time, has undergone many changes, misconceptions and has finally reached the present state. Here we have tried to give you a glimpse of how it has evolved over time, what it actually means, what have we interpreted and what can we learn from it.

Mathematical analysis of a model for thymus infection with discrete and distributed delays

In this paper, the dynamics of mathematical model for infection of thymus gland by HIV-1 is analyzed by applying some perturbation through two different types of delays such as in terms of Hopf bifurcation analysis. Further, the conditions for the existence of Hopf bifurcation are derived by evaluating the characteristic equation. The direction of Hopf bifurcation and stability of bifurcating periodic solutions are determined by employing the center manifold theorem and normal form method. Finally, some of the numerical simulations are carried out to validate the derived theoretical results and main conclusions are included.

Body composition parameters as correlates of coronary artery disease

BACKGROUND & OBJECTIVES

Obesity is a major risk factor for cardiovascular disease (CAD). This study was aimed to assess the risk for CAD determined by certain new and conventional body composition parameters such as visceral fat area (VFA), body mass index (BMI), waist to hip ratio (WHR), etc.

METHODS

We did an age and sex matched case-control study of acute myocardial infarction with 100 participants in a tertiary care hospital (50 cases and 50 controls) representing the serving army personnel. The relation between VFA, per cent body fat (PBF), BMI, waist and hip circumferences, and WHR to CAD was assessed.

RESULTS

The study showed that there was a significantly increased risk for CAD associated with VFA (OR: 5.67; 95% CI: 1.96, 16.95), WHR (7.07; 2.19, 24.27), waist circumference (WC) (2.63; 1.05, 6.66) and BMI (2.53; 1.03, 6.26).

INTERPRETATION & CONCLUSIONS

In conclusion, increased VFA, BMI, WHR and WC showed an association with CAD. VFA is a good index for assessing not only visceral fat accumulation but also cardiovascular risk factors.

Benign mass in tonsil- cavernous hemangioma

Cavernous hemangioma is also called as 'ANGIOMA CAVERNOSUM' or 'CAVERNOMA' as benign lesion of blood vessels. They are similar to strawberry hemangioma but deeply situated. Although most often associated with skin it is also sometimes found in mucous membrane, brain and the viscera. The diagnosis of hemangiomas is mainly based on clinical evaluation . Isolated hemangiomas in the tonsillar tissue is a rare occurance. In this we report had a case of adult tonsillar hemangioma of left side associated with recurrent tonsillitis . He was effectively managed surgically without any complications.

Growth, structural, spectral, optical, and thermal studies on amino acid based new NLO single crystal: L-phenylalanine-4-nitrophenol

A new organic nonlinear optical single crystal, L-phenylalanine-4-nitrophenol (LPAPN) belonging to the amino acid group has been successfully grown by slow evaporation technique. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. FT-IR spectrum was recorded to identify the presence of functional group and molecular structure was confirmed by NMR spectrum. Thermal strength of the grown crystal has been studied using TG-DTA analyses. The grown crystals were found to be transparent in the entire visible region. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm.

Synthesis, structural, optical, thermal and dielectric studies on new organic nonlinear optical crystal by solution growth technique

Single crystals of L-phenylalanine-benzoic acid (LPBA) were successfully grown from aqueous solution by solvent evaporation technique. Purity of the crystals was increased by the method of recrystallization. The XRD analysis confirms that the crystal belongs to the monoclinic system with noncentrosymmetric space group P21. The chemical structure of compound was established by FT-NMR technique. The presence of functional groups was estimated qualitatively by Fourier transform infrared analysis (FT-IR). Ultraviolet-visible spectral analyses showed that the crystal has low UV cut-off at 254 nm combined with very good transparency of 90% in a wide range. The optical band gap was estimated to be 6.91 eV. Thermal behavior has been studied with TGA/DTA analyses. The existence of second harmonic generation (SHG) efficiency was found to be 0.56 times the value of KDP. The dielectric behavior of the sample was also studied for the first time.

Rabies menace and control - An insight into knowledge, attitude and practices

BACKGROUND

There are very few community-based epidemiological studies on knowledge, attitude and practice about rabies prevention and control. This cross-sectional study was undertaken to determine the same in an urban slum area.

METHODS

A random sample of 200 people was selected from an urban slum area. A pre-tested pro-forma was used to collect the data.

RESULT

All study participants had knowledge of rabies transmission by dog bite compared to only 23% having knowledge about its transmission by scratches and licks. Only 40% of the participants were aware that the disease would cause fatal illness. As a first aid measure after dog bite, 66% of the participants responded that they would wash the wound with water, 24% said that they would visit a doctor and the rest responded that either they would do nothing (3%) or would adopt some unconventional methods/religious practices (7%) to prevent the development of rabies. 55.5% of participants were aware about the role of vaccine in preventing rabies.

CONCLUSION

The level of awareness about rabies and its control measures is not high. The attitudes and practices of the respondents reflect the lack of IEC activities, inaccessibility of treatment facilities and the lack of services that would enable community participation in rabies control.

Studies on the structure, stability, and spectral signatures of hydride ion-water clusters

The gas-phase structure, stability, spectra, and electron density topography of H(-)W(n) clusters (where n = 1-8) have been calculated using coupled-cluster CCSD(T) and Møller-Plesset second-order perturbation (MP2) theory combined with complete basis set (CBS) approaches. The performance of various density functional theory (DFT) based methods such as B3LYP, M05-2X, M06, M06-L, and M06-2X using 6-311++G(d,p), and aug-cc-pVXZ (aVXZ, where X = D, T, and Q) basis sets has also been assessed by considering values calculated using CCSD(T)/CBS limit as reference. The performance of the functionals has been ranked based on the mean signed/unsigned error. The comparison of geometrical parameters elicits that the geometrical parameters predicted by B3LYP/aVTZ method are in good agreement with those values obtained at MP2/aVTZ level of theory. Results show that M05-2X functional outperform other functionals in predicting the energetics when compared to CCSD(T)/CBS value. On the other hand, values predicted by M06-2X, and M06 methods, are closer to those values obtained from MP2/CBS approach. It is evident from the calculations that H(-)W(n) (where n = 5-8) clusters adopt several interesting structural motifs such as pyramidal, prism, book, Clessidra, cubic, cage, and bag. The important role played by ion-water (O-H···H(-)) and water-water (O-H···O) interactions in determining the stability of the clusters has also been observed. Analysis of the results indicates that the most stable cluster is made up of minimum number of O-H···H(-) interaction in conjugation with the maximum number of O-H···O interactions. The Bader theory of atoms in molecules (AIM) and natural bond orbital (NBO) analyses has also been carried out to characterize the nature of interactions between hydride ion and water molecules. It can be observed from the vibrational spectra of H(-)W(n) clusters, the stretching frequencies involving ion-water interaction always exhibit larger redshift and intensities than that of water-water (inter solvent) interactions.

Crystal growth, structural, optical, dielectric and thermal studies of an amino acid based organic NLO material: L-phenylalanine L-phenylalaninium malonate

Good transparent single crystals of L-phenylalanine L-phenylalaninium malonate (LPPMA) have been grown successfully by slow evaporation technique from aqueous solution. Single crystal X-ray diffractometer was utilized to measure unit cell parameter and to confirm the crystal structure. The chemical structure of compound was established by FT-NMR technique. The vibrational modes of the molecules of elucidated from FTIR spectra. Its optical behaviour has been examined by UV-vis spectral analysis, which shows the absence of absorbance in the visible region. Thermal properties of the LPPMA crystal were carried out by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) techniques, which indicate that the material does not decompose before melting. The melting point of grown crystal was observed as 180°C by melting point apparatus. The NLO property was confirmed by the powder technique of Kurtz and Perry. The dielectric behaviour of the sample was also studied for the first time.

Control of Clinical Pathogens by the Haemolymph of Paratelphusa hydrodromous, a Freshwater Crab

In the present study, effort has been made to find the antimicrobial activity of haemolymph collected from freshwater crab, Paratelphusa hydrodromous. The haemolymph collected was tested for antimicrobial assay by disc diffusion method against clinical pathogens. Five bacterial species, namely, Escherichia coli, Klebsiella pneumonia, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus, and five fungal strains, namely and Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Rhizopus sp., and Mucor sp., were selected for the study. The result shows a strong response of haemolymph against the clinical pathogens which confirms the immune mechanism of the freshwater crab.

Crystal growth, structural, optical, spectral and thermal studies of tris(L-phenylalanine)L-phenylalaninium nitrate: a new organic nonlinear optical material

Tris(L-phenylalanine)L-phenylalaninium nitrate, C(9)H(12)NO(2)(+)·NO(3)(-)·3C(9)H(11)NO(2) (TPLPN), a new organic nonlinear optical material was grown from aqueous solution by slow evaporation solution growth at room temperature. The grown crystals were subjected to powder X-ray diffraction and single crystal X-ray diffraction studies to confirm the crystalline nature and crystal structure. The modes of vibration of different molecular groups present in TPLPN have been identified by FTIR spectral analysis. The presence of hydrogen and carbon in the grown crystal were confirmed by using proton and carbon nuclear magnetic resonance (NMR) spectral analyses. The optical transmission spectral study establishes good transmitting ability of the crystal in the entire visible region. The thermogravimetric (TG) and differential thermal analyses (DTA) were carried out to understand the thermal stability of the sample. The nonlinear optical property of the compound observed using Kurtz powder second harmonic generation test assets the suitability of the grown material for the frequency conversion of laser radiation of Nd:YAG.

Growth, structural, vibrational, optical, laser and dielectric aspects of L-alanine alaninium nitrate single crystal

Bulk single crystals of l-alanine alaninium nitrate [abbreviated as LAAN], an intriguing material for frequency conversion has been grown from its aqueous solution by both slow solvent evaporation and by slow cooling techniques. The optimized pH value to grow good quality LAAN single crystal was found to be 2.5. The grown crystals were subjected to single crystal X-ray diffraction studies to determine the unit cell dimensions and morphology. Vibrational frequencies of the grown crystals by Fourier transform infrared spectroscopic technique were investigated. Also, the presence of hydrogen and carbon atoms in the grown sample was confirmed using proton and carbon NMR analyses. The dielectric constant and dielectric loss measurements of the as grown crystal at different temperatures and frequencies of the applied field are measured and reported. LAAN has good optical transmission in the entire visible region with cutoff wavelength within the UV region confirms its suitability for device fabrications. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm. Its Laser Damage Threshold (LDT) was measured and also tested by using a Q-switched Nd:YAG laser and the value of LDT of LAAN is 17.76GW/cm2 respectively, is found to be better than certain organic and semiorganic materials.

Determination of oxidative stress markers and their importance in early diagnosis of uremia-related complications

The existence of oxidative stress and the higher incidence of cardiovascular diseases in association with uremia is well proved. The uremic status of serum copper, ceruloplasmin (CP), protein thiols, malonyldialdehyde (MDA), and glutathione S-transferase (GST) levels was studied. The study was carried out on 51 chronic renal failure (CRF) patients who were not on hemodialysis therapy and on 42 healthy controls. Serum urea, creatinine, and MDA levels were found to be significantly increased (P < 0.001), and total protein, albumin, protein thiols, and copper levels were found to be significantly decreased in CRF patients compared to normal controls (P < 0.001). Ceruloplasmin levels were decreased significantly (P < 0.05), and there was no significant change in serum GST levels in CRF patients compared to normal controls. In conclusion, the significant increase in levels of MDA, and the decrease in levels of protein thiols, CP, and copper in uremia patients when compared to controls, reconfirms the presence of stress in this patient population. In view of the changes in other markers of oxidative stress, this absence of any significant change in the activity of GST in uremia patients compared to controls, warrants further study.