Ultra-sensitive quasi-distributed temperature sensor based on an apodized fiber Bragg grating.

This work targets a remarkable quasi-distributed temperature sensor based on an apodized fiber Bragg grating. To achieve this, the mathematical formula for a proposed apodization function is carried out and tested. Then, an optimization parametric process required to achieve the remarkable accuracy that is based on coupled mode theory (CMT) is done. A detailed investigation for the side lobe analysis, which is a primary judgment factor, especially in quasi-distributed configuration, is investigated. A comparison between elite selection of apodization profiles (extracted from related literatures) and the proposed modified-Nuttal profile is carried out covering reflectivity peak, full width half maximum (FWHM), and side lobe analysis. The optimization process concludes that the proposed modified-Nuttal profile with a length (L) of 15 mm and refractive index modulation amplitude (Δn) of 1.4×10-4 is the optimum choice for single-stage and quasi-distributed temperature sensor networks. At previous values, the proposed profile achieves an acceptable reflectivity peak of 10-0.426 dB, acceptable FWHM of 0.0808 nm, lowest side lobe maximum (SL max) of 7.037×10-12 dB, lowest side lobe average (SL avg) of 3.883×10-12 dB, and lowest side lobe suppression ratio (SLSR) of 1.875×10-11 dB. These optimized characteristics lead to an accurate single-stage sensor with a temperature sensitivity of 0.0136 nm/°C. For the quasi-distributed scenario, a noteworthy total isolation of 91 dB is achieved without temperature, and an isolation of 4.83 dB is achieved while applying temperature of 110°C for a five-stage temperature-sensing network. Further investigation is made proving that consistency in choosing the apodization profile in the quasi-distributed network is mandatory. If the consistency condition is violated, the proposed profile still survives with a casualty of side lobe level rise of -73.2070 dB when adding uniform apodization and -46.4823 dB when adding Gaussian apodization to the five-stage modified-Nuttall temperature-sensing network.

Diatoms and diatomaceous earth as novel poultry vaccine adjuvants.

Diatoms are single cell eukaryotic microalgae; their surface possesses a porous nanostructured silica cell wall or frustule. Diatomaceous earth (DE) or diatomite is a natural siliceous sediment of diatoms. Since silica has been proved to have adjuvant capabilities, we propose that diatoms and DE may provide an inexpensive and abundant source of adjuvant readily available to use in livestock vaccines.In a first experiment, the safety of diatoms used as an adjuvant for in-ovo vaccination was investigated. In a second experiment, we assessed the humoral immune response after one in-ovo vaccination with inactivated Newcastle Disease Virus (NDV) and DE as adjuvant followed by 2 subcutaneous boosters on d 21 and 29 of age. In both experiments, results were compared to Freund's incomplete adjuvant and aluminum hydroxide.No detrimental effects on hatchability and chick quality were detected after in-ovo inoculation of diatoms and DE in experiments 1 and 2 respectively. In experiment 2 no humoral responses were detected after the in-ovo vaccination until 29 d of age. Seven d after the second subcutaneous booster an antibody response against NDV was detected in chickens that had received vaccines adjuvanted with Freund's incomplete adjuvant, aluminum hydroxide, and DE. These responses became significantly higher 10 d after the second booster. Finally, 15 d after the second booster, the humoral responses induced by the vaccine with Freund's incomplete adjuvant were statistically higher, followed by comparable responses induced by vaccines containing DE or aluminum hydroxide that were significantly higher than DE+PBS, PBS+INDV and PBS alone. From an applied perspective, we can propose that DE can serve as a potential adjuvant for vaccines against poultry diseases.

Free space optical communications system performance under atmospheric scattering and turbulence for 850 and 1550 nm operation.

In this work, a free space optical communication (FSO) link is proposed and utilized to explore and evaluate the FSO link performance under the joint occurrence of the atmospheric scattering and turbulence phenomena for 850 and 1550 nm operation. Diffraction and nondiffraction-limited systems are presented and evaluated for both wavelengths' operation, considering far-field conditions under different link distances. Bit error rate, pointing error angles, beam divergence angles, and link distance are the main performance indicators that are used to evaluate and compare the link performance under different system configurations and atmospheric phenomena combinations. A detailed study is performed to provide the merits of this work. For both far-field diffraction-limited and nondiffraction-limited systems, it is concluded that 1550 nm system operation is better than 850 nm for the whole presented joint occurrences of atmospheric scattering and turbulence.

Exploring the effect of diffuse reflection on indoor localization systems based on RSSI-VLC.

This work explores and evaluates the effect of diffuse light reflection on the accuracy of indoor localization systems based on visible light communication (VLC) in a high reflectivity environment using a received signal strength indication (RSSI) technique. The effect of the essential receiver (Rx) and transmitter (Tx) parameters on the localization error with different transmitted LED power and wall reflectivity factors is investigated at the worst Rx coordinates for a directed/overall link. Since this work assumes harsh operating conditions (i.e., a multipath model, high reflectivity surfaces, worst Rx position), an error of ≥ 1.46 m is found. To achieve a localization error in the range of 30 cm under these conditions with moderate LED power (i.e., P = 0.45 W), low reflectivity walls (i.e., ρ = 0.1) should be used, which would enable a localization error of approximately 7 mm at the room's center.

Design and performance investigation of a highly accurate apodized fiber Bragg grating-based strain sensor in single and quasi-distributed systems.

In this work, fiber Bragg grating (FBG) strain sensors in single and quasi-distributed systems are investigated, seeking high-accuracy measurement. Since FBG-based strain sensors of small lengths are preferred in medical applications, and that causes the full width at half-maximum (FWHM) to be larger, a new apodization profile is introduced for the first time, to the best of our knowledge, with a remarkable FWHM at small sensor lengths compared to the Gaussian and Nuttall profiles, in addition to a higher mainlobe slope at these lengths. A careful selection of apodization profiles with detailed investigation is performed-using sidelobe analysis and the FWHM, which are primary judgment factors especially in a quasi-distributed configuration. A comparison between the elite selection of apodization profiles (extracted from related literature) and the proposed new profile is carried out covering the reflectivity peak, FWHM, and sidelobe analysis. The optimization process concludes that the proposed new profile with a chosen small length (L) of 10 mm and Δnac of 1.4×10-4 is the optimum choice for single stage and quasi-distributed strain-sensor networks, even better than the Gaussian profile at small sensor lengths. The proposed profile achieves the smallest FWHM of 15 GHz (suitable for UDWDM), and the highest mainlobe slope of 130 dB/nm. For the quasi-distributed scenario, a noteworthy high isolation of 6.953 dB is achieved while applying a high strain value of 1500 µstrain (µÎµ) for a five-stage strain-sensing network. Further investigation was undertaken, proving that consistency in choosing the apodization profile in the quasi-distributed network is mandatory. A test was made of the inclusion of a uniform apodized sensor among other apodized sensors with the proposed profile in an FBG strain-sensor network.

Design and performance evaluation of a dispersion compensation unit using several chirping functions in a tanh apodized FBG and comparison with dispersion compensation fiber.

In this work, various dispersion compensation methods are designed and evaluated to search for a cost-effective technique with remarkable dispersion compensation and a good pulse shape. The techniques consist of different chirp functions applied to a tanh fiber Bragg grating (FBG), a dispersion compensation fiber (DCF), and a DCF merged with an optimized linearly chirped tanh FBG (joint technique). The techniques are evaluated using a standard 10 Gb/s optical link over a 100 km long haul. The linear chirp function is the most appropriate choice of chirping function, with a pulse width reduction percentage (PWRP) of 75.15%, lower price, and poor pulse shape. The DCF yields an enhanced PWRP of 93.34% with a better pulse quality; however, it is the most costly of the evaluated techniques. Finally, the joint technique achieved the optimum PWRP (96.36%) among all the evaluated techniques and exhibited a remarkable pulse shape; it is less costly than the DCF, but more expensive than the chirped tanh FBG.

Growth from birth to adulthood and abdominal obesity in a Brazilian birth cohort.

BACKGROUND: Rapid weight gain in childhood may increase the risk of chronic adult diseases. Few studies have examined the effects of lifecourse weight gain on waist circumference (WC), hip circumference (HC), or waist-to-hip ratio (WHR). OBJECTIVE: To evaluate the effects of birthweight and weight gain from birth to age 23 years on WC, HC, and WHR in young adults. DESIGN: Population-based birth cohort study started in 1982. A sample of 856 individuals was examined in 2006. Conditional growth analyses were carried out with adjustment for confounders. WC and HC were also mutually adjusted. RESULTS: Weight gains during all age ranges studied (birthweight, 0-2, 2-4, 4-15, 15-18/19, and 18/19-23 years) were positively associated with WC and HC in both sexes. These effects were strongest from 4 to 15 years range (beta = 5.0 cm for both circumferences). Proxies for visceral adipose tissue (WHR and WC adjusted for HC) were associated with weight gain after 2 years in females and after 4 years in males. Subcutaneous adipose and muscular tissues, assessed by HC adjusted for WC, were associated with birthweight and weight gain from 0 to 2 years in both sexes, and again with weight gains from 4 to 18 years in males and 4 to 15 years in females. CONCLUSIONS: Weight gains in utero and in the first 2 years had long-term effects on HC, but weight gain after age 4 years was strongly associated with WC. Weight gains up to age 2 years may reduce cardiovascular risk associated with adult fat patterns in a middle-income setting.

Epidemiology of early and late growth in height, leg and trunk length: findings from a birth cohort of Brazilian males.

BACKGROUND/OBJECTIVE: To investigate socioeconomic, gestational and early life exposures as potential determinants of total height, leg and trunk length. SUBJECTS/METHODS: Male subjects from the 1982 Pelotas Birth Cohort Study were examined in 1986 at home, and in 2000 when registering at the local army base. The follow-up rate was 79%. Standing and sitting heights were measured on both occasions. Leg length was calculated as the difference between standing and sitting heights. Outcome measures were height, leg and trunk length at 4 and 18 years and growth in this period. Complete data were obtained for 2012 participants, representing 71% of all eligible male subjects. RESULTS: Mean (s.d.) height, trunk length and leg length at 18 years were 173.4 (6.8), 96.0 (3.5) and 77.5 cm (4.5), respectively. The mean (s.d.) change in height from 1986 to 2000 was 75.4 cm (5.2) and for leg and trunk length 35.4 (3.9) and 40.0 cm (2.9), respectively. Of 11 independent variables analyzed, only maternal height and birthweight were associated with all three variables of growth. Gestational age showed no associations with growth or attained size. CONCLUSIONS: Early growth plays a pivotal role in determining attained height and its components. Both biological and socioeconomic variables strongly influence determinants of height, though socioeconomic factors appear to be more important in early growth. Leg and trunk length contribute almost equally to differences in overall height, regardless of the independent variable influencing the difference. Public health strategies designed to improve chronic disease profiles should focus on the early growth period.

Correlates of C-reactive protein levels in young adults: a population-based cohort study of 3827 subjects in Brazil.

The socio-demographic, behavioral and anthropometric correlates of C-reactive protein levels were examined in a representative young adult Brazilian population. The 1982 Pelotas Birth Cohort Study (Brazil) recruited over 99% of births in the city of Pelotas that year (N = 5914). Individuals belonging to the cohort have been prospectively followed up. In 2004-2005, 77.4% of the cohort was traced, members were interviewed and 3827 individuals donated blood. Analyses of the outcome were based on a conceptual model that differentiated confounders from potential mediators. The following independent variables were studied in relation to levels of C-reactive protein in sex-stratified analyses: skin color, age, family income, education, parity, body mass index, waist circumference, smoking, fat/fiber/alcohol intake, physical activity, and minor psychiatric disorder. Geometric mean (95% confidence interval) C-reactive protein levels for the 1919 males and 1908 females were 0.89 (0.84-0.94) and 1.96 mg/L (1.85-2.09), respectively. Pregnant women and those using oral contraceptive therapies presented the highest C-reactive protein levels and all sub-groups of women had higher levels than men (P < 0.001). Significant associations between C-reactive protein levels were observed with age, socioeconomic indicators, obesity status, smoking, fat and alcohol intake, and minor psychiatric disorder. Associations were stronger at higher levels of C-reactive protein and some associations were sex-specific. We conclude that both distal (socio-demographic) and proximal (anthropometric and behavioral) factors exert strong effects on C-reactive protein levels and that the former are mediated to some degree by the latter.

Correlates of C-reactive protein levels in young adults: a population-based cohort study of 3827 subjects in Brazil

The socio-demographic, behavioral and anthropometric correlates of C-reactive protein levels were examined in a representative young adult Brazilian population. The 1982 Pelotas Birth Cohort Study (Brazil) recruited over 99 percent of births in the city of Pelotas that year (N = 5914). Individuals belonging to the cohort have been prospectively followed up. In 2004-2005, 77.4 percent of the cohort was traced, members were interviewed and 3827 individuals donated blood. Analyses of the outcome were based on a conceptual model that differentiated confounders from potential mediators. The following independent variables were studied in relation to levels of C-reactive protein in sex-stratified analyses: skin color, age, family income, education, parity, body mass index, waist circumference, smoking, fat/fiber/alcohol intake, physical activity, and minor psychiatric disorder. Geometric mean (95 percent confidence interval) C-reactive protein levels for the 1919 males and 1908 females were 0.89 (0.84-0.94) and 1.96 mg/L (1.85-2.09), respectively. Pregnant women and those using oral contraceptive therapies presented the highest C-reactive protein levels and all sub-groups of women had higher levels than men (P < 0.001). Significant associations between C-reactive protein levels were observed with age, socioeconomic indicators, obesity status, smoking, fat and alcohol intake, and minor psychiatric disorder. Associations were stronger at higher levels of C-reactive protein and some associations were sex-specific. We conclude that both distal (socio-demographic) and proximal (anthropometric and behavioral) factors exert strong effects on C-reactive protein levels and that the former are mediated to some degree by the latter.

Effect of the naked neck gene on carcase composition and immunocompetence in chicken.

1. An experiment was conducted to study the effect of naked neck gene (Na) on carcase measurements and some immunological responses of chickens. 2. The presence of naked neck gene in a single or double state increased body weight. 3. The naked neck genotypes (NaNa or Nana) exhibited higher relative weight of dressed carcase, drumstick and breast muscles compared to normally feathered individuals (nana). The proportion of abdominal fat was decreased in both naked neck genotypes compared with normally feathered ones. 4. A higher (non-specific) cell-mediated immune response was evoked in Na gene bearing birds. 5. Higher concentrations of antibodies occurred after injection of sheep red blood cells into naked neck birds, particularly at 14 d post-secondary injection. 6. The NaNa birds had a higher heterophil/lymphocyte ratio than Nana and nana siblings.

Hb A1c in relation to intrauterine growth among male adolescents in southern Brazil.

The fetal origins hypothesis states that nutritional deprivation in utero affects fetal development and contributes to the incidence of diseases associated with the metabolic syndrome in later life. This study investigated whether haemoglobin (Hb) A(1c), an indicator of blood glucose, varied among healthy male adolescents according to their fetal growth rate, in a middle-income setting. Participants were men aged 18 years, belonging to the 1982 Pelotas birth cohort. Complete data, including gestational age and Hb A(1c) at age 18 years, were available for 197 individuals. There was an inverse association between mean Hb A(1c) and birthweight for the gestational age, but not birthweight alone. The association remained significant after adjustment for family income and mother's education, as well as for body mass index at 18 years (P for trend=0.01 and 0.03, respectively).