Effect of thermal expansion mismatch in grating material and host specimen on thermal sensitivity of FBG sensor

Authors have studied thermal sensitivity characteristics of FBG temperature sensor attached to the surface of targeted host specimen (Lee and Lee in J Korean Phys Soc 59(5):3188–3191, 2011; Yu-Lung and Han-Sheng in Meas Sci Technol 9:1543–1547, 1998; Reddy et al. in Opt Appl 40(3):685–692, 2010). In their mathematical analysis, the coefficient of thermal expansion of grating material is ignored due to its contribution to the shift in the wavelength is small as compared to shift because of CTE of host specimen. However, we find that the Bragg’s wavelength shift used for measuring temperature in FBG sensor is dependent on difference in thermal expansions of grating and targeted host specimen materials. We have investigated the effect of the expansion in the material of the grating as well as that of host material and have found that at low temperature the difference in the shift in wavelength is indeed very small of the order of 0.67 pm at \(26\,{^\circ }\hbox {C}\), but the difference in the shift in the wavelength at higher temperature say 350–\(400\,{^\circ }\hbox {C}\) is quite large of the order of 250 pm and cannot be neglected as it will result in error reading of the temperature for higher ranges.     

An Architecture for Exploiting Multihoming in Mobile Devices for Vertical Handovers & Bandwidth Aggregation

In recent years, mobile devices with multihoming capabilities i.e. equipped with multiple network interfaces have gained large scale popularity. This multihoming capability enables the mobile devices to connect with multiple diverse access networks simultaneously. However, networking protocol stack implemented in current devices is not capable of exploiting the availability of multiple network interfaces. Multihoming can be used to provide two important services: vertical handovers and bandwidth aggregation. Vertical handover enables a multihomed device to switch its connectivity from one access network to another access network without disrupting the communication session. Bandwidth aggregation enables multihomed device to achieve higher throughput by establishing simultaneous connections over multiple available network interfaces. A number of solutions have been proposed to exploit multihoming for vertical handovers and bandwidth aggregation. However, most of these solutions either require the support of additional network entities such as host agent, foreign agent, mobility gateway, proxy, etc. or they require changes in current widely deployed protocol stack in operating system kernels. Dependence on either network operator, administrator or operating system vendors hinders the large scale deployment of these solutions. This paper presents an end-to-end architecture that offers the vertical handover and bandwidth aggregation services to TCP applications. This architecture neither requires any additional network entity nor it requires the changes in current networking protocol stack in operating system kernels. The paper presents the design, implementation and performance analysis of the proposed architecture.     

Effect of alloys additions on the interlamellar spacing of pearlite

The spacing of pearlite was measured to investigate the effect of, alloying elements on this parameter using high purity plain carbon, 2 % Co, 2 % Si, 1 % Cr and 0.3 % Mo eutectoid steels. The investigation revealed that the addition of these alloying elements increases the spacing of pearlite at a given undercooling.     

Is there increased sympathetic activity in patients with hypertrophic cardiomyopathy?

OBJECTIVES: This study aimed to assess autonomic nervous system activity in patients with hypertrophic cardiomyopathy. BACKGROUND: Patients with hypertrophic cardiomyopathy are traditionally thought to have increased sympathetic activity. However, convincing evidence is lacking. METHODS: Heart rate variability was assessed from 24-h ambulatory electrocardiographic (Holter) recordings in 31 patients with hypertrophic cardiomyopathy and 31 age- and gender-matched normal control subjects in a drug-free state. Spectral heart rate variability was calculated as total (0.01 to 1.00 Hz), low (0.04 to 0.15 Hz) and high (0.15 to 0.40 Hz) frequency components using fast Fourier transformation analysis. RESULTS: There was a nonsignificant decrease in the total frequency component of heart rate variability in patients with hypertrophic cardiomyopathy compared with that of normal subjects (mean +/- SD 7.24 +/- 0.88 versus 7.59 +/- 0.57 ln[ms2], p = 0.072). Although there was no significant difference in the high frequency component (5.31 +/- 1.14 versus 5.40 +/- 0.91 ln[ms2], p = 0.730), the low frequency component was significantly lower in patients than in normal subjects (6.25 +/- 1.00 versus 6.72 +/- 0.61 ln[ms2], p = 0.026). After normalization (i.e., division by the total frequency component values), the low frequency component was significantly decreased (38 +/- 8% versus 43 +/- 8%, p = 0.018) and the high frequency component significantly increased (16 +/- 6% versus 12 +/- 6%, p = 0.030) in patients with hypertrophic cardiomyopathy. The low/high frequency component ratio was significantly lower in these patients (0.94 +/- 0.64 versus 1.33 +/- 0.55, p = 0.013). In patients with hypertrophic cardiomyopathy, heart rate variability was significantly related to left ventricular end-systolic dimension and left atrial dimension but not to maximal left ventricular wall thickness. No significant difference in heart rate variability was found between 14 victims of sudden cardiac death and 10 age- and gender-matched low risk patients. CONCLUSIONS: Our observations suggest that during normal daily activities, patients with hypertrophic cardiomyopathy experience a significant autonomic alteration with decreased sympathetic tone.     

Antigen density in ELISA; effect on avidity dependency

Two different densities of an antigen (bovine serum albumin, BSA) were used on paper disks is an enzyme-linked immunosorbent assay (ELISA) for chicken IgG anti-BSA antibodies. Disks of different antigen density but containing the same amount of the antigen showed a difference in immunoreactivity. Samples containing large amounts of low avidity antibodies gave higher absorbance when disks of lower antigen density were used. This phenomenon was not due to a competition between antibodies of various immunoglobulin classes. These findings may indicate that antigen density affects the sensitivity of ELISA to antibodies of various avidities.     

Treatment of chondrosarcoma. A retrospective study at the Norwegian Radium Hospital

The authors present a retrospective analysis of 59 chondrosarcoma patients treated at the Norwegian Radium Hospital during the period 1981 to 1993. 31 patients were admitted with untouched tumour, seven after fine needle cytology and 20 after open biopsy or partial excision. One patient had recurrent local disease. Only 20% of the tumours were of high grade malignancy. 51 patients were treated by surgery. Reconstructions were performed in 16 patients, using allografts or endoprostheses. Amputations were performed in six cases and wide excision in 12 cases. In these 18 patients local recurrence appeared in one case, and two developed lung metastases. Only one of the 18 patients operated by amputation or wide excision has since died from chondrosarcoma. Marginal excisions were performed in 26 cases. Nine of these patients developed a local recurrence, five developed metastases and three have died. Six patients had partial excisions. Postoperative radiotherapy was given to one patient only. Five of the six are alive. In one case, the quality of the margins could not be evaluated. A total of 45 of the 51 patients treated for the primary tumour by surgery are alive. The median observation time is four years. Treatment of nonmetastatic chondrosarcoma should be surgical. Chondrosarcoma patients show wider variations in age, localization of tumour and tumour growth rate than patients with other bone sarcomas. Although wide excisions provide the best local control of any grade of malignancy, the mutilation or risk involved may be so great that some patients may benefit from marginal or even partial excision.     

The action spectra of cone photoreceptors in the turtle (Mauremys caspica) retina

Cone photoreceptors in the turtle retina are involved in intricate neuronal interactions with other retinal neurons that modify the responses of the cones to photons absorbed in their outer segments. Therefore, the action spectra of cones strongly depend upon the conditions of measurements. This study describes an attempt to derive the action spectra of turtle cones which are the least distorted by neuronal interactions. To achieve this goal, the photoresponses of cones and horizontal cells were recorded from the turtle retina under different conditions of adaptation using different patterns of the stimulating test flashes. The sensitivity action spectra, derived from small-amplitude (<1 mV) photoresponses, were strongly affected by the recording conditions indicating the contributions of multiple neuronal inputs. Action spectra, constructed from large criterion photoresponses, were less distorted by neuronal interactions and better described the spectral properties of the "isolated" cones. The action spectra of the hyperpolarizing inputs to chromaticity-type horizontal cells were derived by stimulating these cells with mixtures of a saturating red light and a monochromatic light of different wavelength and intensity. The action spectra were constructed from the intensity of the addend component needed to "pull down" the depolarizing response to the red component by a fixed criterion. These spectra, measured in red/green and yellow/blue C-type horizontal cells, are suggested to best represent the "isolated" M-cones and S-cones, respectively.     

Fabrication of high quality zinc-oxide layers through electrohydrodynamic atomization

Zinc oxide (ZnO) is a useful material in the fabrication of many electronic devices because of its wide band-gap, excellent transparency and high electron mobility. Thin films of ZnO have been fabricated where an alcosol solution containing 7 wt.% ZnO nano-particles was synthesized and subjected to controlled flow through a metal capillary exposed to an electric field at the ambient temperature to generate an electrohydrodynamic jet, which subsequently disintegrated into droplets thereby depositing a uniform thin film of zinc oxide on the glass substrates with an average thickness of 115 nm at a constant substrate speed of 0.25 mm/s. Pure and perfectly uniform transparent films with an average transmittance of 88% have been deposited with wurtzite crystal structure and an electrical resistivity of approximately 64 Ω.cm.     

Porosity control in metal-assisted chemical etching of degenerately doped silicon nanowires

We report the fabrication of degenerately doped silicon (Si) nanowires of different aspect ratios using a simple, low-cost and effective technique that involves metal-assisted chemical etching (MacEtch) combined with soft lithography or thermal dewetting metal patterning. We demonstrate sub-micron diameter Si nanowire arrays with aspect ratios as high as 180:1, and present the challenges in producing solid nanowires using MacEtch as the doping level increases in both p- and n-type Si. We report a systematic reduction in the porosity of these nanowires by adjusting the etching solution composition and temperature. We found that the porosity decreases from top to bottom along the axial direction and increases with etching time. With a MacEtch solution that has a high [HF]:[H(2)O(2)] ratio and low temperature, it is possible to form completely solid nanowires with aspect ratios of less than approximately 10:1. However, further etching to produce longer wires renders the top portion of the nanowires porous.