Optical phase extractions based on reassigned continuous wavelet transform with application to simultaneous displacement and velocity measurement.

Instantaneous frequency extraction of a highly nonstationary optical interferometric fringe signal using continuous wavelet transform with Morlet wavelet often fails in the neighborhood of the null phase gradient. The present work reports that the optimal selection of the central frequency and time variance of the Morlet wavelet reduces the spread of wavelet energy to its adjacent bins, and the reassignment technique further sharpens the energy density and enhances accuracy of the extracted instantaneous frequency of the fringe signal. The developed algorithm is applied to a sinusoidal frequency-modulated fringe signal for which the mean square error percentage in normalized instantaneous frequency is determined to be 0.0032 Hz, which is significantly less than 0.0507 Hz obtained with a conventional continuous wavelet transform. Results are also compared with the existing phase stepping technique and found to be more accurate and free from any ripple like nonlinear error for sinusoidal fringe signals. The proposed technique is applied to a fringe signal obtained with a Michelson interferometer, generating displacement profiles that show advantages over those produced by the phase stepping technique. The applicability of the proposed technique is further extended to an arbitrary phase signal.

VISAR signal analysis with an emphasis on ellipse fitting.

A method based on ellipse fitting for analysis of VISAR (Velocity Interferometer System for Any Reflector) signals has been described. The errors introduced on the free surface velocity history due to common measurement imperfections in the amplitude and phase angle of the VISAR signal has been investigated and a remedy to mitigate this using a proper ellipse fitting technique has been presented. Performance comparison among various ellipse fitting techniques based on empirical evidence is carried out, and the geometric fitting technique of the Gauss Newton algorithm with initial conditions from the Bookstein algebraic fitting method is proposed. The new method provides better result in terms of accuracy than existing techniques. The method is especially useful when a fractional fringe signal is present which is quite common in VISAR based measurements. The applicability of the ellipse fitting technique is first theoretically justified, and then numerical simulation of ellipse fitting is carried out. Finally, the proposed method is validated by applying it for the analysis of VISAR signals recorded in the shock wave experiment conducted on the Al-2024T4 target material. The results of present analysis display a good agreement with the data available from other sources.

Chemical ablation of stellate ganglion for head and neck cancer pain.

We present a case of patient with orofacial cancer having pain on one side of face affecting her ability to speak, chew, swallow and sleep leading to emotional and behavioral deterioration. A diagnostic stellate ganglion block was performed followed by chemical neurolysis using phenol under ultrasound guidance, to prevent complications due to inadvertent spread of drug. Her pain scores decreased drastically, she was able to chew and swallow. Weighing the risk of permanent Horner's syndrome or motor paralysis with benefit of improvement in basic functioning of debilitated patients chemical neurolysis of stellate ganglion can be performed with advanced imaging modalities.

Stellate ganglion blockade-techniques and modalities.

Stellate ganglion block (SGB) is utilized in the diagnosis and management of various vascular disorders and sympathetically mediated pain in upper extremity, head and neck. The stellate ganglion lies medial to the scalene muscles, lateral to longus coli muscle, esophagus, trachea and recurrent laryngeal nerve, anterior to C7 transverse process and prevertebral fascia, superior to the subclavian artery and posterior to vertebral vessels. Consequently, inadvertent placement of the needle tip into these soft tissues and vessels occur with blind technique. Henceforth, various interventional modalities are being used for SGB, these have been reviewed in this paper. Various techniques of SGB have been described, and vary from the use of standard blind technique to the use of fluoroscopy, computerized tomography, magnetic resonance imaging, and radio nucleotide tracers. However, these techniques may not be practical in a clinical setting, insofar as they are time consuming, costly, and may involve radiation exposure. The use of fluoroscopy does not visualize the blood vessels close to the stellate ganglion. Ultrasounds are the alternative. They help in visualization of soft tissues to prevent complications and help in deposition of drug subfascially, under direct visual control.

A 10(9) neutrons/pulse transportable pulsed D-D neutron source based on flexible head plasma focus unit.

A 17 kJ transportable plasma focus (PF) device with flexible transmission lines is developed and is characterized. Six custom made capacitors are used for the capacitor bank (CB). The common high voltage plate of the CB is fixed to a centrally triggered spark gap switch. The output of the switch is coupled to the PF head through forty-eight 5 m long RG213 cables. The CB has a quarter time-period of 4 µs and an estimated current of 506 kA is delivered to the PF device at 17 kJ (60 µF, 24 kV) energy. The average neutron yield measured using silver activation detector in the radial direction is (7.1 ± 1.4) × 10(8) neutrons/shot over 4π sr at 5 mbar optimum D2 pressure. The average neutron yield is more in the axial direction with an anisotropy factor of 1.33 ± 0.18. The average neutron energies estimated in the axial as well as in the radial directions are (2.90 ± 0.20) MeV and (2.58 ± 0.20) MeV, respectively. The flexibility of the PF head makes it useful for many applications where the source orientation and the location are important factors. The influence of electromagnetic interferences from the CB as well as from the spark gap on applications area can be avoided by putting a suitable barrier between the bank and the PF head.

Palm top plasma focus device as a portable pulsed neutron source.

Development of a palm top plasma focus device generating (5.2 ± 0.8) × 10(4) neutrons∕pulse into 4π steradians with a pulse width of 15 ± 3 ns is reported for the first time. The weight of the system is less than 1.5 kg. The system comprises a compact capacitor bank, a triggered open air spark gap switch, and a sealed type miniature plasma focus tube. The setup is around 14 cm in diameter and 12.5 cm in length. The energy driver for the unit is a capacitor bank of four cylindrical commercially available electrolytic capacitors. Each capacitor is of 2 µF capacity, 4.5 cm in diameter, and 9.8 cm in length. The cost of each capacitor is less than US$ 10. The internal diameter and the effective length of the plasma focus unit are 2.9 cm and 5 cm, respectively. A DC to DC converter power supply powered by two rechargeable batteries charges the capacitor bank to the desired voltage and also provides a trigger pulse of -15 kV to the spark gap. The maximum energy of operation of the device is 100 J (8 µF, 5 kV, 59 kA) with deuterium gas filling pressure of 3 mbar. The neutrons have also been produced at energy as low as 36 J (3 kV) of operation. The neutron diagnostics are carried out with a bank of (3)He detectors and with a plastic scintillator detector. The device is portable, reusable, and can be operated for multiple shots with a single gas filling.

Note: A portable pulsed neutron source based on the smallest sealed-type plasma focus device.

Development and operation of a portable and compact pulsed neutron source based on sealed-type plasma focus (PF) device are reported. The unit is the smallest sealed-type neutron producing PF device. The effective volume of the PF unit is 33 cm(3) only. A compact size single capacitor (4 µF) is used as the energy driver. A battery based power supply unit is used for charging the capacitor and triggering the spark gap. The PF unit is operated at 10 kV (200 J) and at a deuterium gas filling pressure of 8 mb. The device is operated over a time span of 200 days and the neutron emissions have been observed for 200 shots without changing the gas in between the shots. The maximum yield of this device is 7.8 × 10(4) neutrons/pulse. Beyond 200 shots the yield is below the threshold (1050 neutrons/pulse) of our (3)He detector. The neutron energy is evaluated using time of flight technique and the value is (2.49 ± 0.27) MeV. The measured neutron pulse width is (24 ± 5) ns. Multishot and long duration operations envisage the potentiality of such portable device for repetitive mode of operation.

Note: Printed circuit board based electrically triggered compact rail gap switch.

An electrically triggered rail gap switch has been designed over a commercially available copper clad fiberglass sheet commonly used in making printed circuit boards for applications requiring compact design and direct integration to parallel plate transmission lines. Switch performance has been investigated in terms of its inductance, jitter, and gap closing time. With an electrode separation of 9.0 mm, it has been found to have an inductance of 6 nH, gap closing time of 5 ns, and jitter of about 4-10 ns measured at 95% of self-breakdown voltage. An application of this switch has been demonstrated as an electrically exploding foil accelerator developed over the same board and velocities up to 1.6 km/s have been achieved on Kapton flyers with diameter of 3.0 mm and thickness of 125 microm using a compact 1 microF capacitor bank.

Shock experiments and numerical simulations on low energy portable electrically exploding foil accelerators.

Two low energy (1.6 and 8 kJ) portable electrically exploding foil accelerators are developed for moderately high pressure shock studies at small laboratory scale. Projectile velocities up to 4.0 km/s have been measured on Kapton flyers of thickness 125 microm and diameter 8 mm, using an in-house developed Fabry-Perot velocimeter. An asymmetric tilt of typically few milliradians has been measured in flyers using fiber optic technique. High pressure impact experiments have been carried out on tantalum, and aluminum targets up to pressures of 27 and 18 GPa, respectively. Peak particle velocities at the target-glass interface as measured by Fabry-Perot velocimeter have been found in good agreement with the reported equation of state data. A one-dimensional hydrodynamic code based on realistic models of equation of state and electrical resistivity has been developed to numerically simulate the flyer velocity profiles. The developed numerical scheme is validated against experimental and simulation data reported in literature on such systems. Numerically computed flyer velocity profiles and final flyer velocities have been found in close agreement with the previously reported experimental results with a significant improvement over reported magnetohydrodynamic simulations. Numerical modeling of low energy systems reported here predicts flyer velocity profiles higher than experimental values, indicating possibility of further improvement to achieve higher shock pressures.

Miniaturized magneto-optic sensor for pulsed magnetic field measurements.

The design and performance of a miniaturized magneto-optic probe using a terbium doped paramagnetic glass are described. The compactness and simplicity of the device are achieved by using the polarizer sheets obtained from a commonly available liquid crystal display. Plastic optical fibers are used to transport the light. A pulsed magnetic field up to 48 T has been generated and measured using high-voltage capacitor discharge in single-turn coils. A rise time and magnetic field-dependent anomalous behavior is observed in the terbium glass characteristics at room temperature.

P53, COX-2, iNOS protein expression changes and their relationship with anti-oxidant enzymes in surgically and multi-modality treated esophageal carcinoma patients.

Esophageal carcinoma has a high incidence in India but its etiology remains unknown. In the present study the correlation between apoptosis regulatory proteins and anti-oxidant enzymes in 40 esophageal carcinoma patients was examined. Patients in one group were operated by transhiatal esophagectomy and in the second group were administered cisplatin (30 mg/m2/day) and 5-fluorouracil (5-FU) (750 mg/m2/day) daily for three days followed by surgery after four weeks of neo-adjuvant therapy (NAT). Complete pathological response was achieved in 15% of patients. Results obtained by Western blot analysis showed over-expressed p53 and COX-2 protein levels in the tumor tissues as compared to the adjoining tissue and its paired normal mucosa in both groups of patients. Immunohistochemical studies showed heterogenous p53 staining pattern with sections showing both nuclear and cytoplasmic staining with 36.8% mild, 10.5% moderate and 52.6% intense p53 immunoreactivity. Both COX-2 and iNOS immunostaining revealed 25% negative and 75% mild to strongly positive immunoreactivity. Correlation studies demonstrated a positive relationship between p53 and COX-2 (P=0.030; r = +0.70) in surgically treated patients. The association of COX-2 and p53 with various anti-oxidant enzymes showed a significantly positive correlation between COX-2 expression and catalase activity and an inverse correlation between p53 expression and superoxide dismutase and catalase activity in the tumor tissue of patients given NAT. In addition, we observed a negative trend between p53 expression levels and GPx enzyme levels in both the adjoining and tumor tissue of patients having undergone surgery as main mode of treatment.

Low dose gamma-irradiation differentially modulates antioxidant defense in liver and lungs of Balb/c mice.

PURPOSE: To evaluate the effect of low-dose (<50 cGy) whole body ?-irradiation on the antioxidant defense system in the liver and the lungs of mice at various post-irradiation intervals. MATERIALS AND METHODS: Male Balb/c mice, 5 - 6 weeks of age, were divided into irradiated and non-irradiated groups. Whole body irradiation was done with gamma-rays from a (60)Co source at doses of 10, 25 and 50 cGy (48.78 cGy/min). Lipid peroxidation and antioxidant status were measured in the liver and the lungs at 4, 12 and 24 h after irradiation. RESULTS: Lipid peroxidation increased by 1.38 and 2.0 fold in lung and liver respectively at 12 h after exposure to 25 cGy. Whole body exposure to 25 and 50 cGy significantly (p < 0.05) increased the hepatic reduced glutathione at 4 h. Reduced glutathione continued to rise until 12 h and returned to the basal level at 24 h, whereas in the lungs it remained elevated until 24 h at 10 and 25 cGy. Antioxidant enzymes activities for superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase increased by 1.22, 1.13, 1.22 and 1.11 fold respectively (p < 0.05) in the liver at 4 h after exposure to 50 cGy and remained elevated at almost the same level up to 12 h after exposure. Surprisingly these antioxidant defense enzymes remained unaltered in the lung at the above radiation doses. CONCLUSIONS: Low-dose whole body gamma-irradiation differentially modulates the antioxidant defense system in the liver and lungs of mice. The induction of endogenous glutathione, immediately after exposure to low-dose -irradiation, may be beneficial in protecting the cells from reactive oxygen species (ROS) induced oxidative stress.