Study of dynamic characteristics of air cavity resonances from tyre-pavement interaction noise using single frequency filtering

Air cavities in the tyre tread and the gap formed between tyre and pavement are excited during vehicle movement on a pavement. The former results in pipe resonance, and the latter results in horn resonance. These effects will be varying with speed of the vehicle and also because of conditions of tyre, pavement and, tyre-pavement interaction (TPI). The objective of this paper is to study the dynamic characteristics of air cavity resonances from the signals of the tyre-pavement interaction noise, which was collected by a pair of microphones, when a two wheeler is driven on a pavement at different speeds. The dynamic characteristics of the resonances are analysed using single frequency filtering (SFF) analysis of signals. The method gives spectral information at every sampling instant. The effects of impacts of the tyre treads, pavement characteristics, and TPI on the resulting cavity resonances are examined at four different vehicle speeds and for two different types of pavements. The analysis shows that the SFF spectra bring out the distinct characteristics of the pavements on the formation of air cavities and excitation of the resonances of these cavities. This analysis may help in determining the condition of the tyre and pavement.

Time-Frequency analysis of acoustic signals from tyre-pavement interaction

The acoustic responses of a dynamical system reflect the characteristics of the external excitation and vibrating system. The objective in an identification problem is to characterise the system and excitation from the measured responses. This becomes challenging if the characteristics of the dynamical system are time-varying. The analysis of the acoustic signal generated as a result of the tyre-pavement interaction (TPI) is one such situation, where in order to study the time-varying nature there is a need to obtain the characteristics of the instantaneous response. This study explores the single frequency filtering analysis of signals to examine the time-varying characteristics of tyre-pavement interaction noise (TPIN). Field measurements of TPI acoustic signals were obtained for a two-wheeler driven at different speeds on asphalt and cement concrete pavements. The time-frequency characteristics of the tyre tread impact and of the air cavity resonances are analysed by investigating the effect of vehicular speed and pavement type on TPIN. The specific features of TPIN such as the harmonics due to periodic tread impact and the frequency response due to resonances of the air cavities are examined in detail. The analysis presented in this paper will be useful in developing methods for health monitoring of tyre and pavement systems.

Detection of Clostridium perfringens alpha toxin gene in lambs by loop mediated isothermal amplification

Aim:

The loop mediated isothermal amplification (LAMP) was standardized for rapid detection of Clostridium perfringens.

Materials and Methods:

A total of 120 fecal samples were collected from enterotoxemia suspected lambs were used for screening of C. perfringens cpa gene by LAMP. The specificity of the LAMP amplified products was tested by digesting with restriction enzyme XmnI for alpha toxin gene.

Results:

Out of 120 samples screened 112 (93.3%) samples were positive by both LAMP and polymerase chain reaction (PCR) for detection of cpa gene which indicated the equal sensitivity of both the tests. The enzyme produced single cut in 162 base pair amplified product of alpha toxin gene at 81 base pair resulting in a single band in gel electrophoresis.

Conclusion:

Both LAMP and PCR for detection of cpa gene indicated the equal sensitivity of both the tests. Standardization of LAMP reaction for amplification of epsilon and beta toxin genes will help to identify the C. perfringens toxin types from the clinical samples. The test could be a suitable alternative to the PCR in detection of toxin types without the help of sophisticated machinery like thermal cycler. Considering its simplicity in operation and high sensitivity, there is the potential use of this technique in clinical diagnosis and surveillance of infectious diseases.

Residue dynamics of spirotetramat and imidacloprid in/on mango and soil

Spirotetramat is a unique insecticide having both phloem and xylem mobility and imidacloprid, a neonicotinoid insecticide, is one of the most widely used in the world. The combination formulation is very effective against sucking pests of mango. Residue dynamics of spirotetramat and imidacloprid in/on mango and soil was studied following application of the combination formulation, spirotetramat 12% + imidacloprid 12% (240 SC) at 90 and 180 g a.i. ha(-1). Spirotetramat residues in/on mango fruits were 0.327 and 0.483 mg kg(-1) after giving 3 applications at 90 and 180 g a.i. ha(-1), respectively. The residues remained on mango fruits for 7 days and dissipated with the half-life of 3.3 and 5.2 days, respectively. Residues of spirotetramat-enol, the major metabolite of spirotetramat in plant, were not detected in mango fruits. Initial residues of imidacloprid on mango fruits from the two treatments were 0.329 and 0.536 mg kg(-1), respectively. Imidacloprid residues remained on mango fruits beyond 15 days and dissipated with the half-life of 5.2 and 8.2 days. The residues of spirotetramat, spirotetramat-enol and imidacloprid were found below quantifiable limit of 0.05 mg kg(-1) in mature mango fruits and field soil at harvest.

Comparative evaluation of oxygen saturation levels using pulse oxymeter during nonsurgical and surgical periodontal therapy in chronic periodontitis patients

BACKGROUND AND AIM

Monitoring is the global method of observation and data recording in relation to body organ and system function that afford constant information to ensure continuous evalutation of the patient's physical condition. Basic monitoring provides essential information for assessing the vital signs, both circulatory and respiratory, and fundamentally comprises the control of blood pressure (BP) and heart rate (HR) and rhythm. Pulse oxymetry is used to record HR and oxygen saturation. The objective of the study was to assess and compare hemodynamic changes by monitoring oxygen saturation level changes during periodontal surgical and nonsurgical therapy.

MATERIALS AND METHODS

A cross-sectional observational study was conducted in 30 chronic periodontitis patients. Patients were divided into two groups; Group A consisted of 15 patients undergoing surgical periodontal therapy, Group B consisted of 15 patients undergoing nonsurgical periodontal therapy. The hemodynamic changes were evaluated by monitoring HR and oxygen saturation level using pulse oxymeter (SaO₂). HR and SaO₂ were monitored continuously and registered pre-operatively, i.e. 10 minutes before the procedure, intra-operatively and postoperatively, i.e. 10 minutes after the procedure. One-way analysis of variance test (ANOVA) was performed for data analysis.

RESULTS

Both the groups showed a slight fall in oxygen saturation levels intraoperatively, but within the normal range. More decrease in oxygen saturation levels was observed in nonsurgical periodontal therapy as compared to surgical periodontal therapy at intraoperative levels. The differences in the values were statistically significant. There was no statistical difference seen in the postoperative and preoperative values.

CONCLUSION

Most of the hemodynamic changes induced during the periodontal therapy were within normal limits, taking into consideration the anxiety and stress produced by the surgical intervention. The hemodynamic change was more in nonsurgical as compared to surgical periodontal therapy.

Acute toxoplasmosis in nonstem cell transplant patients with haematological malignancies: a study from a regional cancer institute in South India

The frequency of Toxoplasma gondii (Tgondii) infections was investigated during febrile episodes in nonstem cell transplant patients with haematological malignancies (HM). One hundred and sixty-two febrile episodes in 125 HIV-negative patients with HM undergoing treatment at Kidwai Memorial Institute of Oncology, Bangalore, India comprised the study group. Plasma from anticoagulated whole blood was used for amplifying the B1 gene of T. gondii by nPCR. Specific antibodies to T. gondii (IgM and IgG) were tested using commercial kits. Corticosteroid and cotrimoxazole usage during these episodes was 50 and 41%, respectively. Twenty-two of the febrile episodes (14%) were positive for T. gondii; nine of which did not have any other concomitant infecting pathogen and were seen in symptomatic patients. While majority of these (13%) were 'Toxoplasma infection', there was a single case of 'probable Toxoplasma disease' (0.6%). In four of the fatal febrile episodes, T. gondii was the causative agent; two of which did not have any other concomitant infection. None of the patients had undergone stem cell transplantation.

Detection of Bacillus cereus in foods by colony hybridization using PCR-generated probe and characterization of isolates for toxins by PCR

Isolates of Bacillus cereus from traditional Indian foods were detected by colony hybridization using the PCR-generated phospholipase (PL-1) probe. In all, 29 isolates picked up by the probe were confirmed as B. cereus by conventional cultural and biochemical characteristics. All the isolates reacted positively in PCR with phospholipase (PL-1) primers. Among the native isolates, 11 of them showed the discontinuous pattern of haemolysin BL activity in gel diffusion assay. Though 14 isolates reacted positively in PCR with primers (Ha-1) specific to the B gene of haemolysin BL, only four of them showed both the presence of gene and haemolysin BL activity. More than 50% of the isolates indicated their potential enterotoxigenicity by reacting positively with primers specific for the BceT gene encoding for diarrhoeal enterotoxin. PCR with primers for different inverse (IS) repeat elements revealed that isolates carrying transposon IS 231-P 231-1 did not carry IS 240-P 240. Some of the isolates were devoid ofthese IS elements. The study demonstrated the potential of using of a PCR-generated labelled PL-1 probe for the direct detection of B. cereus in food samples and PCR for characterizing the toxigenic isolates.

Hypoglycemic, diuretic and hypocholesterolemic effect of winter cherry (Withania somnifera, Dunal) root

Hypoglycemic, diuretic and hypocholesterolemic effects of roots of W. somnifera (ashvagandha) were assessed on human subjects. Six mild NIDDM subjects and six mild hypercholesterolemic subjects were treated with the powder of roots of W. somnifera for 30 days. Suitable parameters were studied in the blood and urine samples of the subjects along with dietary pattern before and at the end of treatment period. Decrease in blood glucose was comparable to that of an oral hypoglycemic drug. Significant increase in urine sodium, urine volume, significant decrease in serum cholesterol, triglycerides, LDL (low density lipoproteins) and VLDL (very low density lipoproteins) cholesterol were observed indicating that root of W. somnifera is a potential source of hypoglycemic, diuretic and hypocholesterolemic agents. Clinical observations revealed no adverse effects.