Search

A comparative study is done on Si, 4H-SiC, Wz-GaN and InP based impact avalanche transit time (IMPATT) diodes operating at 94 GHz. A double-iterative simulation procedure is utilized to investigate the DC and small-signal features of the diodes from which corresponding avalanche response times and transit times are obtained. The studies exhibit that SiC and GaN diodes are potential sources for radiating high power at 94 GHz. It is also observed that SiC and GaN diodes are highly appropriate for mm-wave frequency bands due to shorter values of their avalanche response time. The power output for SiC IMPATT source is noticed as 47.61Wand for GaN IMPATT, the same is seen as 1.96 W; corresponding avalanche response times are found to be 2.42×10-15 and 3.45×10-16 s respectively. [ABSTRACT FROM AUTHOR]

In this paper, the effect of position shifting of charge bump on different microwave parameters, such as the negative resistance, noise measure, quality factor, and series resistance of one-dimensional different compound semiconductor-based DDR IMPATT structures, has been studied using the advanced computer iterative method. A comparison of a crucial parameter, negative resistance, of these devices is obtained for different charge bump positions at different frequencies of a Ka band. The noise measure has been carried out also varying with these different charge bump positions at the depletion layer as noise measure strongly depends on the negative resistance value. Quality factor also varies for these changes of the charge bump position. The noise measurement plays an important role in the choice of structures and operating frequency of the IMPATT device. So, throughout the Ka band, the parameters of these different compound semiconductor-based IMPATT diodes for different charge bump positions are measured and compared and will be well suited for the optimum design in the Ka band. [ABSTRACT FROM AUTHOR]

This paper examines the generation of elastic SH-waves in a medium of two-quarter spaces in welded contact with a layer of uniform thickness overlying one of the quarter spaces. Impulsive surface tractions on the surface generate the waves. Transform methods are employed to obtain the functional integral equation in the general case. Approximations are made when a layer overlies a halfspace to obtain the solution. The displacement at the surface of the layer is obtained as a series of definite integrals representing the different pulses reflected at the interface between the layer and the halfspace. [ABSTRACT FROM AUTHOR]

In this study, a computerized diagnosis system is developed using Rough set classifier from multi-lead ECG signal for detection as well as the classification of five different types of myocardial infarction (MI) disease. The pathological features of ECG such as Inverted T-wave, ST segment deviation, or pathological Q wave, which are seen during MI, are extracted. An Information table and the knowledgebase are expanded from these pathological features after getting feedback from the cardiologist as well as consulting different medical books. The Information table contains 36 features and 341objects which include normal and five types of MI such as Anterior (AN), Inferior (IN), Antero lateral (ANLA), Inferior lateral (INLA), and Antero septal (ANSE) are used for assessment. The proposed system determines the degree of attributes dependency and their significance to find a smaller set of attributes, called reduct, alike the original set to predict the appropriate decision rules for MI classification. The robustness is justified by the "five-fold cross" validation technique using RSES tools. Finally, the proposed classifier illustrates its outperformance over the existing approaches in terms of sensitivity (99.75%), and accuracy (99.8%) for MI detection and 99.8% accuracy for MI classification. [ABSTRACT FROM AUTHOR]

Objective: To estimate the disease and economic burden of pertussis amongst hospitalised infants in India. Design: Multicentric hospital-based surveillance study. Participants: Hospitalised infants with clinical suspicion of pertussis based on predefined criteria. Outcome measures: Proportion of infants with laboratory-confirmed pertussis, economic burden of pertussis amongst hospitalised infants. Results: 693 clinically suspected infants were recruited of which 32 (4.62%) infants had laboratory-confirmed pertussis. Progressive cough with post-tussive emesis (50%) and pneumonia (34%) were the common clinical presentations; apnea in young infants was significantly associated with pertussis. Infants with pertussis were more likely to be younger (median age 102.5 days vs. 157 days) and born preterm (42.9% vs 24.5%). Almost 30% infants with pertussis had not received vaccine for pertussis with 50% of these infants aged less than 2 months. Pertussis was associated with higher costs of hospitalisation, pharmacy and loss of working days by caregivers as compared to non-pertussis cases. Conclusion: Younger infants, those born preterm and those inadequately immunised against pertussis are at higher risk of pertussis infection. Timely childhood immunisation and introduction of maternal immunisation for pertussis can help in reducing the disease burden. [ABSTRACT FROM AUTHOR]

This paper is scrutinised elaborately to traverse the probability and potency of type-IIb diamond as a semiconducting substance of double-drift region (DDR) impact ionisation avalanche transit time (IMPATT) diode working at terahertz (THz) frequencies. Initially, a simulation review exposes that the upward cut-off frequency of type-IIb diamond IMPATT is 1.5 THz, whereas that for Si IMPATT is 0.5 THz. Drift-diffusion technique has been employed to review the DC and high-frequency parameter of type-IIb diamond and Si DDR IMPATTs at THz. Simulation experiment exhibits that diamond IMPATT device provides maximum RF power output of 929 mW with 17.71% conversion efficiency, whereas Si IMPATT provides a maximum RF power output of 483 mW with 6.26% conversion efficiency. Therefore, a correlative research has been built on IMPATT devices made of type-IIb diamond and Si at THz frequencies. [ABSTRACT FROM AUTHOR]

A circularly polarized (CP) CPW-fed (CoPlanar Waveguide) with two asymmetric U-shaped strips, patch antenna is described in this paper. The antenna consists of a radiating patch composed of a hexagonal-ring connected with two annular rings on the two corners, which provide wide CP. The CPW-fed antenna was constructed by etching out two L-shaped slots and adding two asymmetric U-shaped strips to the ground, which greatly enhanced both the impedance bandwidth (IBW) and axial ratio bandwidth (ARBW). The proposed antenna design yields a measured wide IBW = 5.637 GHz (4.484–10.121 GHz), which is about 80.53% with respect to the center frequency fc = 7.3 GHz. The simulated 3-dB axial ratio (AR) bandwidth for tri bands includes 95 MHz (1.37%), 186 MHz (2.35%) and 149 MHz (1.67%) resonating at 6.95, 7.93, and 8.91 GHz, respectively. The radiation characteristics of the implemented antenna have been analyzed and discussed in this paper. The maximum simulated peak gain is 5.968 dBi at 6.063 GHz. The proposed antenna can be suitable for C- and X-band wireless communication applications. [ABSTRACT FROM AUTHOR]

A field experiment was conducted to evaluate the effect of FeS04, MnS04 and their combination on growth and flowering of Tagetes erecta cv. Siracole. Highest linear growth (68.88cm) of marigold was recorded in plants treated with 0.25%MnS04+ 0.25%FeS04. Plant spread (63.79cm), number of branches (19.10), leaf area (5.36cm.sq.), fresh and dry matter accumulation (431.69g & 105.59g), crop growth rate (7.98 g/m.sq./days), biomass duration (2783.03 g.days), number of flowers per plant (78.66), yield of flowers (35.99 t/ha) and petal meal per kilogram of fresh flowers (390.3 g/kg) and carotene content (2.26mg/g) were recorded highest in plants treated with 0.5 % FeS04+ 0.25 %MnS04 at all stages of crop growth. Plant chlorophyll and iron content were recorded highest with 0.5%FeS04 while manganese content was significantly increased with the application of MnS04@0.5%. [ABSTRACT FROM AUTHOR]

Background: While people with intellectual disability (ID) face disparities relating to sexual and reproductive health (SRH) services, little is known about the role of family caregivers who assist women and girls with ID access SRH services. This scoping review examined the findings of studies to elucidate the role of family caregivers with regard to SRH for women and girls with ID. Method: We used Arksey and O'Malley's six‐stage scoping framework, with Levac, Colquhoun and O'Brien's revisions, to evaluate identified sources. We searched three electronic databases, six ID journals and reference lists in full‐text articles. Inclusion criteria included (1) primary and secondary source research studies in peer‐reviewed journals; (2) published in English; (3) all research methodologies (i.e. qualitative, quantitative, mixed methods and systematic reviews or commentaries); (4) published between 2000 and 2016; and (5) studies from any country. Results: The search yielded 2062 studies; 57 articles met inclusion criteria. Most studies employed purposive, convenience or criterion sampling. Participants included people with ID, family caregivers, paid caregivers and health‐care professionals. Findings were summarised thematically: (1) menstruation and menopause; (2) vaccinations and preventive screenings; (3) supporting sexuality and healthy relationships; (4) coordinating with health‐care providers and (5) contraception and sterilisation. Conclusions: Findings from this scoping review underscore the need for more and better‐quality research, including how family caregivers assist women and girls with ID access perinatal and preventive SRH services and sexual abuse education. Family caregivers, women and girls with ID and health‐care providers need increased access to information about SRH. [ABSTRACT FROM AUTHOR]

This paper highlights the effect of temperature on the high-frequency performance of the double avalanche region avalanche transit time (ATT) source capable of operating in multiple numbers of frequency bands. The variance of static (DC) and large-signal properties on temperature are accounted by utilizing a well-established authors' developed simulation method. The large-signal admittance characteristics of the source show the presence of discrete and far separated negative conductance bands which can yield a wide tuning capability of it. Here in this paper, linear changes of DC parameters as well as non-linear changes of large-signal parameters with junction temperature have been studied; with the help of utilizing linear and quadratic polynomial curve fitting method, analytical expressions are obtained which represent the DC and high-frequency parameters of the source as functions of junction temperature. These will be very much beneficial for optimization of thermal design-related issues of the ATT sources. [ABSTRACT FROM AUTHOR]

We propose a theory of field induced crystal nucleation in disordered glass structure applicable to chalcogenide phase change memory. In the region of symmetry breaking strong electric fields, the nucleation is dominated by cylinder shaped particles with bias dependent nucleation barriers. Statistical fluctuations in microscopic structure of a glass translate into probabilistic distributions of induction times and threshold voltages having respectively log-normal and normal shape. These distributions are exponentially sensitive to the applied voltage, temperature, and material parameters. [ABSTRACT FROM AUTHOR]

We present the data on temporal (t) drift of parameters in chalcogenide phase change memory that significantly complement the earlier published results. The threshold voltage Vth and the amorphous state resistance R are shown to drift as ΔVth∝v ln t and R∝tα in broad intervals spanning up to nine decades in time; the drift coefficient v depends on glass parameters and temperature, but does not depend on device thickness. We have demonstrated that drift saturates at long enough times that can be shorten with temperature increase. All available data on drift dynamics are fully consistent with the classical double-well-potential model, which gives simple analytical expressions for the observed temporal dependencies including numerical parameters. [ABSTRACT FROM AUTHOR]

We report a summary of our recent study of piezo- and pyroelectricity in CdS-based photovoltaics including CdTe and CuIn(Ga)Se2 absorber devices. The strong pyro- and piezo-effects in CdS significantly affect the electric field distribution and the physics of device operations. We introduce the concept of pyro-photovoltaic coupling where the photovoltaic effect and the CdS polarization strongly depend on each other. Our quantitative modeling shows that the CdS polarization turns out to be beneficial for photovoltaic technology, making it more forgiving. Three experimental setups utilized in our work were aimed at exerting mechanical stresses corresponding to the device squeezing, bending, and flexing; we used the substrate, superstrate, and flexible substrate structures. Our understanding points at previously unexplored venues in thin-film photovoltaic technology. [ABSTRACT FROM AUTHOR]

Co doped ZnO nanoparticles were synthesized by a simple rheological phase reaction-precursors method using zinc acetate, cobalt acetate, and oxalic acid for different atomic percentages of Co doping. X-ray diffraction studies confirmed the correct phase formation, and the composition were obtained from the x-ray photoelectron spectroscopic studies. Particle size was obtained from the small angle x-ray scattering studies. It was observed that the static dielectric constant, calculated from the shift of band gap energy, shows a gradual decrease with Co doping. A simple theoretical model was developed to explain the observed change of dielectric constant on the doping concentration. The model could successfully describe the dependence of the static dielectric constant on the doping concentration. [ABSTRACT FROM AUTHOR]

Observations of the redshifted 21-cm hyperfine line of neutral hydrogen from early phases of the Universe such as Cosmic Dawn and the Epoch of Reionization promise to open a new window onto the early formation of stars and galaxies. We present the first upper limits on the power spectrum of redshifted 21-cm brightness temperature fluctuations in the redshift range z  = 19.8–25.2 (54–68 MHz frequency range) using 14 h of data obtained with the LOFAR-Low Band Antenna (LBA) array. We also demonstrate the application of a multiple pointing calibration technique to calibrate the LOFAR-LBA dual-pointing observations centred on the North Celestial Pole and the radio galaxy 3C220.3. We observe an unexplained excess of |$\sim 30\!-\!50{{\ \rm per\ cent}}$| in Stokes / noise compared to Stokes V for the two observed fields, which decorrelates on ≳12 s and might have a physical origin. We show that enforcing smoothness of gain errors along frequency direction during calibration reduces the additional variance in Stokes I compared Stokes V introduced by the calibration on sub-band level. After subtraction of smooth foregrounds, we achieve a 2σ upper limit on the 21-cm power spectrum of |$\Delta _{21}^2 \lt (14561\, \text{mK})^2$| at |$k\sim 0.038\, h\, \text{cMpc}^{-1}$| and |$\Delta _{21}^2 \lt (14886\, \text{mK})^2$| at |$k\sim 0.038 \, h\, \text{cMpc}^{-1}$| for the 3C220 and NCP fields respectively and both upper limits are consistent with each other. The upper limits for the two fields are still dominated by systematics on most k modes. [ABSTRACT FROM AUTHOR]

Background: Women with intellectual and developmental disabilities (IDD) in the USA are bearing children at increasing rates. However, very little is known whether racial and ethnic disparities in birth outcomes and labour and delivery‐related charges exist in this population. This study investigated racial and ethnic disparities in birth outcomes and labour and delivery‐related charges among women with IDD. Methods: The study employed secondary analysis of the 2004–2011 Healthcare Cost and Utilization Project National Inpatient Sample, the largest all‐payer, publicly available US inpatient healthcare database. Hierarchical mixed‐effect logistic and linear regression models were used to compare the study outcomes. Results: We identified 2110 delivery‐associated hospitalisations among women with IDD including 1275 among non‐Hispanic White women, 527 among non‐Hispanic Black women and 308 among Hispanic women. We found significant disparities in stillbirth among non‐Hispanic Black and Hispanic women with IDD compared with their non‐Hispanic White peers [odds ratio = 2.50, 95% confidence interval (CI): 1.16–5.28, P < 0.01 and odds ratio = 2.53, 95% CI: 1.08–5.92, P < 0.01, respectively]. There were no racial and ethnic disparities in caesarean delivery, preterm birth and small‐for‐gestational‐age neonates among women with IDD. The average labour and delivery‐related charges for non‐Hispanic Black and Hispanic Women with IDD ($18 889 and $22 481, respectively) exceeded those for non‐Hispanic White women with IDD ($14 886) by $4003 and $7595 or by 27% and 51%, respectively. The significant racial and ethnic differences in charges persisted even after controlling for a range of individual‐level and institutional‐level characteristics and were 6% (ln(β) = 0.06, 95% CI: 0.01–0.11, P < 0.05) and 9% (ln(β) = 0.09, 95% CI: 0.03–0.14, P < 0.01) higher for non‐Hispanic Black and Hispanic Women with IDD compared with non‐Hispanic White women with IDD. Conclusions: Our findings highlight the need for an integrated approach to the delivery of comprehensive perinatal services for racial and ethnic minority women with IDD to reduce their risk of having a stillbirth. Additionally, further research is needed to examine the causes of racial and ethnic disparities in hospital charges for labour and delivery admission among women with IDD and ascertain whether price discrimination exists based on patients' racial or ethnic identities. [ABSTRACT FROM AUTHOR]

In this paper a comparative study has been made on IMPATT diodes based on group IVIV materials such as Si, SiC(4H) and group III-V materials such as GaN(Wz), InP for different bias current densities operating at W-band frequency. A double iterative computer method based on drift-diffusion model has been used to study the DC and small signal admittance properties of the device and corresponding avalanche response times as well as transit times are calculated. The simulation studies show that 4H-SiC from group IV-IV and Wz-GaN from group III-V based devices are potential source for generating high RF power at W-band. It is also observed that SiC(4H) based IMPATTs from group IV-IV and GaN(Wz) based IMPATTs from group III-V are highly suitable for operation at higher mm-wave frequencies due to smaller value of avalanche response time. The maximum RF power output for 4H-SiC is found to be 47.61 Watt and for Wz-GaN, it is found to be 1.96 Watt. The Minimum Avalanche response time of 2.35×10-15s and 3.43×10-16s is obtained for 4H-SiC and Wz-GaN based IMPATTs respectively. [ABSTRACT FROM AUTHOR]

Cotton fabric was coated with aqueous dispersion containing blend of natural rubber latex (NRL), polyvinyl alcohol (PVA) and starch following a knife-over-roll technique to produce moisture vapour permeable waterproof coating. Coating of cotton with a formulation containing NRL, 15% aqueous PVA and tamarind kernel seed powder as starch, in the ratio of 1:3: 0.3 in presence of a typical sulphur curing system, followed by drying of the coated fabric at 95 °C for 5 min and subsequent vulcanization at 120 °C for 2 h produced most balanced improvements in the properties of the coated fabric such as, waterproofness, breathability as revealed by moisture vapour transmission rate, coating adhesion, tensile properties, abrasion resistance and flex endurance. Incorporation of PVA makes the coating permeable to moisture vapour and such property is promoted further in presence of starch in the coating formulation. Examination of surface morphology of vulcanized coating by scanning electron microscopy revealed that poly vinyl alcohol crystals formed clusters of dimensions of only few microns in the rubber matrix. Such clusters of PVA served as conduits for transportation of moisture vapour through the film of NRL while acting as an effective barrier to liquid water droplets. [ABSTRACT FROM AUTHOR]

Objective Hypopituitarism diagnosed in childhood, adolescence and young adulthood has the potential to affect growth and somatic development. Less is known about the impact of such a diagnosis on other aspects of development. Design An analysis of the KIMS database (Pfizer International Metabolic Database) was performed to explore social, educational and vocational outcomes of adult patients diagnosed in childhood, adolescence and young adulthood compared with adult-onset controls. Patients A total of 2952 adult patients diagnosed with hypothalamic pituitary conditions before the age of 25 were divided into two groups: childhood-onset [<16 years ( CO)] ( n = 1782) and young-adult-onset [16 to <25 years ( YAO)] ( n = 1170). A total of 1617 adult patients diagnosed with a nonfunctioning pituitary adenoma at the age of 25 or older formed the adult-onset control group ( AO). Measurements KIMS Patient Life Situation Form which provided information on social, educational and vocational outcomes. Results Compared with the AO control group, CO and YAO patients were between 4·5 and 8·0 times more likely to live with their parents in adulthood; CO and YAO patients were also less likely to live in partnership and to have children. The impact on educational and vocational outcomes was less marked than on social outcomes with no significant differences compared with the AO control group. Educational and vocational outcomes showed the lowest level in male and female CO and YAO patients who had been previously diagnosed with a brain tumour. Conclusions Social outcomes were more affected than educational and vocational outcomes. Although CO patients are more adversely affected, YAO patients were also failing to achieve social milestones. This has consequences for the delivery of endocrine care in both paediatric and adult services. [ABSTRACT FROM AUTHOR]

The influence of optical illumination on DC and high frequency performance of Ka-band DDR IMPATT diode with different semiconductor materials like 4H-SiC, GaAs, InP, Si are investigated in this paper. A double iterative computer simulation method is formulated based on drift and diffusion model under dark condition as well as under illumination. The associated effect of the DC and small signal parameters under optical illumination through optical windows on both Top Mounted (TM) and Flip Chip (FC) structures were studied. The simulation results are compared and the result shows that the optical control have parallel effect in both FC and TM counterpart concerning the reduction of output power and shifting of operating frequency. Finally 4HSiC evolve as a most useful material for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Nanostructures of bismuth (Bi) are obtained by employing solvothermal process. Two different shapes, nanorods and nanospheres, are produced by changing the ratio of solvents (1) ethylene glycol (EG) and (2) EG and absolute ethanol (AE) in the ratio of 1:1, respectively. Prepared samples are characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy and transmission electron microscopy. Transport properties measured on the pressed pellets of bismuth nanostructures exhibit metallic behavior. The room temperature conductivity varies from 64 to 18 S/cm depending on morphology of the nanostructure. The thermal conductivity is found to be ~50 times lower in nanostructures than that of single crystal bismuth. Thermoelectric performances like power factor and figure of merit are correlated with the porosities of the samples, which show higher value for sphere-like than that of rod-like Bi nanostructures. [ABSTRACT FROM AUTHOR]

Noise performance and output power generation of Ka-band DDR IMPATT diode has been investigated through the method of simulation. The iterative method has been used to study the effect of doping on the noise performance and power generation of this device. Effect of doping on noise parameters like noise measure, shot noise ratio and generated output power of compound semiconductor based IMPATTs (like InP, 3C SiC, 4H SiC, 6H SiC) are studied. It is interestingly found that output power can be increased and noise measure can be decreased by increasing doping concentration maintaining a proper doping level. It is obtained that 6H SiC produces minimum noise measure only 10.9072 dB at 300 Kelvin and 3C SiC has the capability of generation of maximum output power 248.6 miliwatt at Ka Band among these devices. 4H SiC shows maximum efficiency 26.3932% and maximum breakdown voltage (VB) 554.1919 volt at Ka Band. Results of the analysis presented in this paper will be useful to realize a comparative study of noise suppression technique of different semiconductor based IMPATTs at Ka band. [ABSTRACT FROM AUTHOR]

The couple stress theory developed by Eringen comprises granular materials as also composite fibrous materials. As such, micropolar materials present an inclusive model of composite materials. This article endeavors to study aspects of wave propagation in a random weakly thermal micropolar elastic medium. The smooth perturbation technique has been employed. The classical thermoelasticity has been used. Six different types of waves have been observed to propagate in the random interacting medium. Dispersion equations have been derived. The effects due to random variations of micropolar elastic and thermal parameters have been observed. Change of phase speed occurs on account of randomness. Attenuation coefficients for high-frequency waves have been computed. Second moment properties have been discussed with application to wave propagation in the random micropolar elastic medium. 36 + 1 components of the associated Green’s tensor have been computed. Integrals involving correlation functions have been transformed to radial forms. A special type of correlation function has been used to approximately measure effects of random variations of parameters. [ABSTRACT FROM AUTHOR]

Non-invasive detection of Atrial Fibrillation (AF) and Atrial Flutter (AFL) from ECG at the time of their onset can prevent forthcoming dangers for patients. In most of the previous detection algorithms, one of the steps includes filtering of the signal to remove noise and artefacts present in the signal. In this paper, a method of AF and AFL detection is proposed from ECG without the conventional filtering stage. Here Phase Rectified Signal Average (PRSA) technique is used with a novel optimized windowing method to achieve an averaged signal without quasi-periodicities. Both time domain and statistical features are extracted from a novel SQ concatenated section of the signal for non-linear Support Vector Machine (SVM) based classification. The performance of the proposed algorithm is tested with the MIT-BIH Arrhythmia database and good performance parameters are obtained, as indicated in the result section. [ABSTRACT FROM AUTHOR]

This paper presents a software-based scheme for reliable and robust Electrocardiogram (ECG) data compression and its efficient transmission using Second Generation (2G) Global System for Mobile Communication (GSM) based Short Message Service (SMS). To achieve a firm lossless compression in high standard deviating QRS complex regions and an acceptable lossy compression in the rest of the signal, two different algorithms have been used. The combined compression module is such that it outputs only American Standard Code for Information Interchange (ASCII) characters and, hence, SMS service is found to be most suitable for transmitting the compressed signal. At the receiving end, the ECG signal is reconstructed using just the reverse algorithm. The module has been tested to all the 12 leads of different types of ECG signals (healthy and abnormal) collected from the PTB Diagnostic ECG Database. The compression algorithm achieves an average compression ratio of ∼22.51, without any major alteration of clinical morphology. [ABSTRACT FROM AUTHOR]