A two-dimensional (2D) potential distribution model for the short gate-length ion-implanted GaAs mesfets under dark and illuminated conditions

An analytical 2D model to predict the potential distribution of short-channel ionimplanted GaAs MESFETs has been presented. The 2D potential distribution in the channel of the short-channel device has been obtained by solving the 2D Poisson’s equation in conjunction with suitable boundary conditions using superposition method. The remarkable feature of the proposed model is that the implanted doping profile has been treated in completely analytical manner. A double-integrable Gaussian-like function has been assumed as the doping distribution profile in the vertical direction of the channel. The effects of excess carrier generation due to the incident optical radiation in channel region have been included in the Poisson’s equation to study the optical effects on the device. The photovoltage developed across the gate metal has also been modeled. The proposed model has been verified by comparing the theoretically predicted results with simulated data obtained by using the commercially available ATLASTM2D device simulator. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2785

A doping dependent threshold voltage model of uniformly doped short-channel symmetric double-gate (DG) MOSFET’s

The paper presents a doping dependent threshold voltage model for the short-channel double-gate (DG) MOSFETs. The channel potential has been determined by solving the two-dimensional (2D) Poisson’s equation using the parabolic potential approximation in the vertical direction of channel. Threshold voltage sensitivity on acceptor doping and device parameters is discussed in detail. The threshold voltage expression has been modified by incorporating the effects of band gap narrowing for highly doped DG MOSFETs. Quantum mechanical corrections have also been employed in the threshold voltage model. The theoretical results have been compared with the ATLASTM simulation results. The present model is found to be valid for acceptor doping variation from 1014 cm–3 to 5 × 1018cm–3. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2789

Oral human papillomavirus (HPV) infection in men who have sex with men: prevalence and lack of anogenital concordance.

To estimate the prevalence of oral detectable human papillomavirus (HPV) DNA in HIV-negative men who have sex with men (MSM) attending a sexual health clinic in London and concordance with anogenital HPV infection. Such data are important to improve our understanding of the epidemiology of oral HPV and the potential use of vaccines to prevent oropharyngeal cancers

The Stress of COVID-19: Playing Havoc with the Hormones-A Review

Severe acute respiratory syndrome coronavirus- 2 (SARS-CoV-2) has affected millions of people across the world engendering an unprecedented pandemic. Coronavirus disease (COVID)-19 can present asymptomatic or in the form of the acute respiratory syndrome, viral pneumonia,or sepsis. Due to the novelty of the disease, the endocrine manifestations are not fully understood. It becomes indispensable to address the underlying endocrine disruptions contributing to the severe form of illness and thereby increasing the mortality.We discuss here the SARS-CoV-2 virus and endocrine reverberations based on the research with structurally similar SARS-COV-1. SARS-CoV-2 enters the body via its attachment to the angiotensin-converting enzyme 2 (ACE2) receptors. Apart from lungs,ACE2 expression on various organs can lead to endocrine perturbations.In COVID-19 infection, pre-existing endocrine disorders warrant cautious management and may require replacement therapy. COVID-19 and its repercussions on hormones are discussed extensively in this review

Mathematical investigations of gas flare constituents in oil producing regions of Malaysia

Air pollution due to gas–flaring is a major concern in most region of the world. The short and long term effect of the massive air pollution on the life form within the area requires urgent attention because of the health implication. This research examines the impact of air pollutants in oil producing region of Malaysia using remotely sensed satellite data. The satellite data set was obtained from CALIPSO, MODIS and AIRS. A mathematical software (MATLAB) was used to analyse the results. For Sulphur dioxide (SO2), Kemaman had the highest rate of pollution (0.075DU), then Petronas (0.074DU), Kertih (0.067 DU), Port (0.065DU), Rapids (0.052DU), Melaka 1 (0.032DU) respectively. For Carbon dioxide (CO2), Kertih and Petronas was the most polluted with (382.33ppmv), Melaka 1 and Port had (382.27ppmv), Rapid had (382.04ppmv) and Kemaman (381.53ppmv) respectively. For Nitrogen dioxide (NO2), Petronas had the highest mean value with (311.18mol/cm2), Melaka 1 (243.4mol/cm2), Port (201.5mol/cm2), Rapids (183.3mol/cm2), Kertih (117.73mol/cm2), Kemaman (95.7mol/cm2) respectively. For Ozone (O3), the stations with the highest rate of concentration were Rapids, Melaka 1, Petronas, Kertih and Kemaman with (252.43E+2mol/cm2). Mathematical projections were made to capture the dilemma- people in this region might encounter in the nearest future

Genetic programming assisted stochastic optimization strategies for optimization of glucose to gluconic acid fermentation

This article presents two hybrid strategies for the modeling and optimization of the glucose to gluconic acid batch bioprocess. In the hybrid approaches, first a novel artificial intelligence formalism, namely, genetic programming (GP), is used to develop a process model solely from the historic process input-output data. In the next step, the input space of the GP-based model, representing process operating conditions, is optimized using two stochastic optimization (SO) formalisms, viz., genetic algorithms (GAs) and simultaneous perturbation stochastic approximation (SPSA). These SO formalisms possess certain unique advantages over the commonly used gradient-based optimization techniques. The principal advantage of the GP-GA and GP-SPSA hybrid techniques is that process modeling and optimization can be performed exclusively from the process input-output data without invoking the detailed knowledge of the process phenomenology. The GP-GA and GP-SPSA techniques have been employed for modeling and optimization of the glucose to gluconic acid bioprocess, and the optimized process operating conditions obtained thereby have been compared with those obtained using two other hybrid modeling-optimization paradigms integrating artificial neural networks (ANNs) and GA/SPSA formalisms. Finally, the overall optimized operating conditions given by the GP-GA method, when verified experimentally resulted in a significant improvement in the gluconic acid yield. The hybrid strategies presented here are generic in nature and can be employed for modeling and optimization of a wide variety of batch and continuous bioprocesses

Preliminary investigation of the antioxidant, anti-diabetic, and anti-inflammatory activity of Enteromorpha intestinalis extracts

Marine algae are a promising source of potent bioactive agents against oxidative stress, diabetes, and inflammation. However, the possible therapeutic effects of many algal metabolites have not been exploited yet. In this regard, we explored the therapeutic potential of Enteromorpha intestinalis extracts obtained from methanol, ethanol, and hexane, in contrasting oxidative stress. The total phenolic (TPC) and flavonoids (TFC) content were quantified in all extracts, with ethanol yielding the best values (about 60 and 625 mg of gallic acid and rutin equivalents per gram of extract, respectively). Their antioxidant potential was also assessed through DPPH•, hydroxyl radical, hydrogen peroxide, and superoxide anion scavenging assays, showing a concentration-dependent activity which was greater in the extracts from protic and more polar solvents. The α-amylase and α-glucosidase activities were estimated for checking the antidiabetic capacity, with IC50 values of about 3.8 μg/mL for the methanolic extract, almost as low as those obtained with acarbose (about 2.8 and 3.3 μg/mL, respectively). The same extract also showed remarkable anti-inflammatory effect, as determined by hemolysis, protein denaturation, proteinase and lipoxygenase activity assays, with respectable IC50 values (about 11, 4, 6, and 5 μg/mL, respectively), also in comparison to commercially used drugs, such as acetylsalicylic acid

Mathematical modelling long-term effects of replacing Prevnar7 with Prevnar13 on invasive pneumococcal diseases in England and Wales

England and Wales recently replaced the 7-valent pneumococcal conjugate vaccine (PCV7) with its 13-valent equivalent (PCV13), partly based on projections from mathematical models of the long-term impact of such a switch compared to ceasing pneumococcal conjugate vaccination altogether. A compartmental deterministic model was used to estimate parameters governing transmission of infection and competition between different groups of pneumococcal serotypes prior to the introduction of PCV13. The best-fitting parameters were used in an individual based model to describe pneumococcal transmission dynamics and effects of various options for the vaccination programme change in England and Wales. A number of scenarios were conducted using (i) different assumptions about the number of invasive pneumococcal disease cases adjusted for the increasing trend in disease incidence prior to PCV7 introduction in England and Wales, and (ii) a range of values representing serotype replacement induced by vaccination of the additional six serotypes in PCV13. Most of the scenarios considered suggest that ceasing pneumococcal conjugate vaccine use would cause an increase in invasive pneumococcal disease incidence, while replacing PCV7 with PCV13 would cause an overall decrease. However, the size of this reduction largely depends on the level of competition induced by the additional serotypes in PCV13. The model estimates that over 20 years of PCV13 vaccination, around 5000–62000 IPD cases could be prevented compared to stopping pneumococcal conjugate vaccination altogether. Despite inevitable uncertainty around serotype replacement effects following introduction of PCV13, the model suggests a reduction in overall invasive pneumococcal disease incidence in all cases. Our results provide useful evidence on the benefits of PCV13 to countries replacing or considering replacing PCV7 with PCV13, as well as data that can be used to evaluate the cost-effectiveness of such a switch

Reduction in HPV 16/18 prevalence in sexually active young women following the introduction of HPV immunisation in England.

BACKGROUND: Reduction in the prevalence of vaccine type HPV infection in young women is an early indication of the impact of the HPV immunisation programme and a necessary outcome if the subsequent impact on cervical cancer is to be realised. METHODS: Residual vulva-vaginal swab (VVS) specimens from young women aged 16-24 years undergoing chlamydia screening in community sexual health services (formerly known as family planning clinics), general practice (GP), and youth clinics in 2010-2012 were submitted from 10 laboratories in seven regions around England. These specimens were linked to demographic and sexual behaviour data reported with the chlamydia test, anonymised, and tested for type-specific HPV DNA using a multiplex PCR and Luminex-based genotyping test. Estimated immunisation coverage was calculated and findings were compared to a baseline survey conducted prior to the introduction of HPV immunisation in 2008. RESULTS: A total of 4664 eligible specimens were collected and 4178 had a valid test result. The post-immunisation prevalence of HPV 16/18 infection was lowest in this youngest age group (16-18 years) and increased with age. This increase with age was a reversal of the pattern seen prior to immunisation and was inversely associated with estimates of age-specific immunisation coverage (65% for 16-18 year olds). The prevalence of HPV 16/18 infection in the post-immunisation survey was 6.5% amongst 16-18 year olds, compared to 19.1% in the similar survey conducted prior to the introduction of HPV immunisation. CONCLUSIONS: These findings are the first indication that the national HPV immunisation programme is successfully preventing HPV 16/18 infection in sexually active young women in England. The reductions seen suggest, for the estimated coverage, high vaccine effectiveness and some herd-protection benefits. Continued surveillance is needed to determine the effects of immunisation on non-vaccine HPV types

Human papillomavirus DNA in men who have sex with men: type-specific prevalence, risk factors and implications for vaccination strategies.

BACKGROUND: Human papillomavirus (HPV) vaccination of girls will have relatively little effect on HPV-related disease in men who have sex with men (MSM). We determined HPV prevalence and risk factors in MSM to inform the potential effectiveness of vaccinating MSM. METHODS: Cross-sectional study of 522 MSM aged 18-40 attending a London sexual health clinic who completed a computer-assisted self-interview. Urine and two swabs (anal and penile/scrotal/perianal) were collected and tested using an in-house Luminex-based HPV genotyping system. RESULTS: Prevalence of DNA of the vaccine-preventable HPV types in ano-genital specimens of men was 87/511 (17.0%), 166/511 (32.5%) and 232/511 (45.4%) for the bivalent (HPV16/18), quadrivalent (HPV6/11/16/18) and nonavalent (HPV6/11/16/18/31/33/45/52/58) vaccine types, respectively. A total of 25.1% had one of the quadrivalent types, and 7.4% had 2+ types. Median age at first anal sex was 19 (IQR 17-23) and at first clinic attendance was 24 (IQR 20-27). The increase in the odds of any HPV infection per year of age was 4.7% (95% CI 1.2-8.4). CONCLUSIONS: On the basis of the current infection status, most MSM, even among a high-risk population attending a sexual health clinic, are not currently infected with the vaccine-type HPV. A targeted vaccination strategy for MSM in the UK could have substantial benefits