Numerical and experimental investigation of FBG strain response at cryogenic temperatures

Strain response of FBG sensors are investigated at various temperatures from 298 K to 4.2 K. Numerical modelling is carried out for acrylate coated, substrate-free fiber Bragg grating (FBG) sensors at room temperature of 298 K and cryogenic temperatures of 77 K, 10 K and 4.2 K. A 1550 nm Bragg wavelength (λB) FBG sensor is modelled and simulated for applied strain (ε) ranging from 0 to 800 µm/m. The Bragg wavelength shifts (ΔλB) thus obtained are compared with the experimentally investigated values obtained by subjecting the FBG sensor to axial strain, with its sensing part not being bonded to any surface. The MTS25 tensile machine with a cryostat under vacuum conditions (10-4 mbar pressure) is used for the experiments and the required temperatures are maintained using liquid Nitrogen (LN2) and compressed Helium gas (He). The Bragg wavelength shift (ΔλB) versus induced strain (ε) is regressed with a linear polynomial function and the strain sensitivity obtained in both the cases are discussed

A Prototype for Intrusion Detection in Wireless Sensor Networks Using Data Mining Methods

The Wireless Sensor Networks (WSNs) are highly distributed networks of tiny, light-weight wireless nodes, placed in large numbers to monitor the environment or system. Monitoring the system includes the measurement of physical parameters such as pressure, temperature, relative humidity and passing their data to the main node (sink). WSN faces various security attacks which can affect the overall performance and security of the system. So, it is necessary to detect and prevent the attacks on WSN. Intrusion Detection is one of the major and efficient method against attacks. Intrusion Detection Systems can act as a second line of defence and it provides security primitives to prevent attacks against computer networks. This paper focuses on a hybrid approach for intrusion detection system (IDS) based on data mining techniques. The approach is clustering analysis with the aim to improve the detection rate and decrease the false alarm rate

A Note on the Determination of Ricochet Trace of Small arms Ammunition

A method of obtaining the relationship between various parameters governing the ricochet phenomenon of a projectile has been described. The experimental procedures for determining such parameters and their use have also been discussed

Bioluminescence assay of adenosine triphosphate in drug susceptibility testing of Mycobacterium tuberculosis

Twenty three clinical isolates of M. tuberculosis and the reference strain, M. tuberculosis H37Rv were tested for their susceptibility to trifluoperazine (TFP) by the standard broth dilution method and the bioluminescence assay. The results showed that in 15 of the 23 isolates, the minimal inhibitory concentration (MIC) was identical in both the methods and in the remaining 8 isolates the difference in the MIC values between the methods, was less than two fold and was not significant. The findings suggest that the measurement of adenosine triphosphate (ATP) by bioluminescence assay can be employed as an alternative method for the rapid screening of clinical isolates for their susceptibility to anti-mycobacterial agents

Mutual Constraints Between Reionization Models and Parameter Extraction From Cosmic Microwave Background Data

Spectroscopic studies of high-redshift objects and increasingly precise data on the cosmic microwave background (CMB) are beginning to independently place strong complementary bounds on the epoch of hydrogen reionization. Parameter estimation from current CMB data continues, however, to be subject to several degeneracies. Here, we focus on those degeneracies in CMB parameter forecasts related to the optical depth to reionization. We extend earlier work on the mutual constraints that such analyses of CMB data and a reionization model may place on each other to a more general parameter set, and to the case of data anticipated from the $MAP$ satellite. We focus in particular on a semi-analytic model of reionization by the first stars, although the methods here are easily extended to other reionization scenarios. A reionization model can provide useful complementary information for cosmological parameter (CP) extraction from the CMB, particularly for the degeneracies between the optical depth and either of the amplitude and index of the primordial scalar power spectrum, which are still present in the most recent data. Alternatively, by using a reionization model, known limits on astrophysical quantities can reduce the forecasted errors on CPs. Forthcoming CMB data also have the potential to constrain the sites of early star formation, as well as the fraction of baryons that participate in it. Finally, we examine the implications of an independent, e.g., spectroscopic, determination of the epoch of reionization for the determination of CPs from the CMB. This has the potential to significantly strengthen limits from the CMB on parameters such as the index of the power spectrum, while having the considerable advantage of being free of the choice of the reionization model (abridged).Comment: Accepted on 15 Feb. 2002 for publication in ApJ, 22 pages with 4 figures; paper's text expanded significantly, new Discussion section, results (table and figures) unchanged from version

Immune response & modulation of immune response induced in the guineapigs by Mycobacterium avium complex (MAC) & M. fortuitum complex isolates from different sources in the south Indian BCG trial area

A total of 139 guineapigs were used to study the immune response and its modulation induced by Mycobacterium avium complex (MAC) and M. fortuitum complex strains obtained from different sources in the south Indian BCG trial area. The guineapigs were divided into groups and some were directly sensitised/immunised with different MAC strains, M. fortuitum complex strain or BCG and others were sensitised with MAC or M. fortuitum complex and then immunised with BCG. The resulting delayed type hypersensitivity (DTH) response in the different groups of guineapigs was studied by skin tests using PPD-RT23 and PPD-B, and protective response was studied by challenging the guineapigs with a south Indian low virulent strain of M. tuberculosis and enumerating the bacilli in spleen at different points of time. The 3 strains of MAC induced similar low levels of DTH to PPD-RT23 but much higher and varying levels of DTH to PPD-B. MAC strains from soil and sputum induced different levels of immune modulation during subsequent immunisation with BCG on the DTH response to PPD-RT23 and PPD-B. At 2 wk after challenge, 23.8, 81 and 90.5 per cent protection was induced by the standard strain, soil isolate and sputum isolate of MAC, respectively, while 33.3 per cent protection was induced by the M. fortuitum complex strain compared to the protection induced by BCG alone. Prior exposure to MAC or M. fortuitum complex did not have any modulatory effect on the protective immunity due to BCG at this time point. However, at 6 wk after challenge, while the guineapigs immunised with BCG were protected, modulation of the protective response resulting from BCG was observed in the guineapigs sensitised with MAC and M. fortuitum from soil

Evaluation of Procedures for Isolation of Nontuberculous Mycobacteria from Soil and Water

Six methods of decontamination each for the isolation of mycobacteria from soil and water were compared. On the basis of the results obtained. three of the six methods for soil and two of the six methods for water were further evaluated. For both soil and water samples, the method using 3% sodium lauryl sulfate in combination with 1% NaOH yielded more positives than the other methods