Enhancement of VCO Linearity and Phase Noise by Implementing Frequency Locked Loop

This paper investigates the on-chip implementation of a frequency locked loop (FLL) over a VCO that decreases the phase noise and linearizes the transfer function. Implementation of the FLL inside a PLL is also investigated and a possible application is highlighted. Design of a special kind of low noise frequency detector without a reference frequency (frequency-to-voltage converter), which is the most critical component of the FLL, is also presented in a 0.25 ¿m BiCMOS process. Linearization and approximately 15 dBc/Hz phase noise suppression is demonstrated over a moderate phase noise LC VCO with a center frequency of 10 GHz

45% power saving in a 0.25μm BiCMOS 10Gb/s 50Ω-terminated packaged active-load laser driver

A 0.25mum BiCMOS laser driver based on active loads allows operation at 10Gb/s while drawing 5mA from a 1.8V supply. The design guarantees the correct matching of the driver outputs without the use of physical 50Omega load resistors. This enables a theoretical current consumption reduction of 50% (45% in the actual prototype) compared to the traditional laser-driver design

Evaluation of choroidal thickness in cases with age-related macular degeneration

AIM: To compare subfoveal choroidal thickness(SFCT)between cases with non-neovascular age-related macular degeneration(AMD)and neovascular AMD by optical coherence tomography(OCT)and to evaluate the contribution of choroidal thickness(CT)measurements to the understanding of pathogenesis of neovascularization in AMD.<p>METHODS: Fourty-eigth eyes of 24 patients who had neovascular AMD in one eye and non-neovascular AMD in the other eye were included in this retrospective, cross- sectional study as study group. Forty eyes of healthy,age and axial length matched individuals were selected as the control group. Eyes with drusen and/or pigmentary changes were included in the non-neovascular AMD subgroup. Eyes with subretinal or intraretinal fluid and/orlipid exudation due to the choroidal neovascularization were included in the neovascular AMD subgroup. OCT measurements were performed with RTVue 100-2(V 5.1, Optovue, Fremont, CA, USA)perpendicularly from the outer part of the hyperreflective line(retinal pigment epithelial layer)to the line corresponding to the choroido- scleral junction. Choroidal thickness was measured at 7 different points, 500μm intervals up to 1500μm temporal and nasal to the fovea in the study group and compared statistically between subgroups.<p>RESULTS: The mean age of patients was 72.4±8.97(60- 82)y. The mean age of healthy individuals was 71.2±8.8(58-81)y. Mean SFCT of neovascular AMD group were significantly thicker than non-neovascular AMD group(<i>P</i><0.05). In non-neovascular AMD group, there was no statistically significant difference between the mean SFCT and the mean temporal-nasal choroid thickness(<i>P</i>>0.05). In neovascular AMD group, there was a statistically significant difference between the mean SFCT and the mean temporal-nasal choroid thickness(<i>P</i><0.05).<p>CONCLUSION: Choroidal thickness measurements with OCT device can make a contribution to the understanding the phatophysiology of AMD and large prospective studies should be conducted to understand why SFCT was thicker in neovascular AMD

Menopausal symptoms assessment among middle age women in Kushtia, Bangladesh

<p>Abstract</p> <p>Background</p> <p>There are few menopausal study data available in South East Asia especially in Bangladesh. This study was conducted in a well populated town named Kushtia, which is located in the western part of Bangladesh.</p> <p>Objectives</p> <p>This study was aimed to document the menopausal-related symptoms among middle age women of Kushtia region of Bangladesh.</p> <p>Methods</p> <p>By using modified MRS (Menopause Rating Scale) questionnaire, 509 women aged 40-70 years were interviewed to document symptoms commonly associated with menopause.</p> <p>Findings</p> <p>The mean age of menopause was 51.14 years. The most prevalent symptoms reported include, feeling tired (92.90%); headache (88.80%); joint and muscular discomfort (76.20%); physical and mental exhaustion (60.90%) and sleeplessness (54.40%) which are followed by depressive mood (37.30%); irritability (36%); dryness of vagina (36%); hot flushes and sweating (35.80%); anxiety (34.20%). However, noted less frequent symptoms were sexual problem (31.20%); cardiac discomfort (19.10%) and bladder problem (12.80%).</p> <p>Conclusions</p> <p>The prevalence of menopausal symptoms found in this study correspond to other studies on Asian women however the prevalence of classical menopausal symptoms of hot flushes and sweating were lower compared to studies on Caucasian women.</p

Frequency of symptoms, determinants of severe symptoms, validity of and cut-off score for Menopause Rating Scale (MRS) as a screening tool: A cross-sectional survey among midlife Nepalese women

<p>Abstract</p> <p>Background</p> <p>Majority of Nepalese women live in remote rural areas, where health services are not easily accessible. We determined the validity of Menopause Rating Scale (MRS) as a screening tool for identification of women with severe menopausal symptoms and cut-off MRS score for referral.</p> <p>Methods</p> <p>A cross-sectional survey was carried out between February and August, 2008. Trained health workers administered MRS and a questionnaire to 729 women (40 to 65 years) attending health screening camps in Kaski district of Western Development Region of Nepal. Information about demographics, menopausal status, and use of hormone replacement therapy (HRT), chronic disease, self-perceived general health and reproductive history was also collected. Menopausal status was classified according to the Staging of Reproductive Ageing Workshop (STRAW). We calculated rates of menopausal symptoms, sensitivity, and specificity and likelihood ratios of MRS scores for referral to a gynaecologist. We also carried out multivariate analyses to identify the predictors for referral to a gynaecologist for severe symptoms.</p> <p>Results</p> <p>A total 729 women were interviewed. Mean age at menopause was 49.9 years (SD 5.6). Most frequently reported symptoms were, sleeping problems (574, 78.7%), physical and mental exhaustion (73.5%), hot flushes (508, 69.7%), joint and muscular discomfort (500, 68.6%) and dryness of vagina (449, 61.6%). Postmenopausal women (247, 33.9%) and perimenopausal (215, 29.5%) women together experienced significantly higher prevalence of all symptoms than the premenopausal (267, 36.6%) women. MRS score of ≥16 had highest ratio for (sensitivity + specificity)/2. Women who reported urogenital symptoms [OR 5.29, 95% CI 2.59, 10.78], and self perceived general health as poor [OR 1.29, 95% CI 1.11, 1.53] were more likely to be referred to a gynaecologist for severe menopausal symptoms. While women reporting somatic [OR 0.72, 95% CI 0.63, 0.82] and psychological [OR 0.86, 95% CI 0.74, 0.99] symptoms were less likely to be referred.</p> <p>Conclusion</p> <p>MRS may be used as a screening tool at a cut-off score of ≥16 with least misclassification rate. However, its utility may be limited by woman's general health status and occurrence of urogenital symptoms.</p

Amyloid and tau pathology associations with personality traits, neuropsychiatric symptoms, and cognitive lifestyle in the preclinical phases of sporadic and autosomal dominant Alzheimer’s disease

Background Major prevention trials for Alzheimer’s disease (AD) are now focusing on multidomain lifestyle interventions. However, the exact combination of behavioral factors related to AD pathology remains unclear. In 2 cohorts of cognitively unimpaired individuals at risk of AD, we examined which combinations of personality traits, neuropsychiatric symptoms, and cognitive lifestyle (years of education or lifetime cognitive activity) related to the pathological hallmarks of AD, amyloid-β, and tau deposits. Methods A total of 115 older adults with a parental or multiple-sibling family history of sporadic AD (PREVENT-AD [PRe-symptomatic EValuation of Experimental or Novel Treatments for AD] cohort) underwent amyloid and tau positron emission tomography and answered several questionnaires related to behavioral attributes. Separately, we studied 117 mutation carriers from the DIAN (Dominant Inherited Alzheimer Network) study group cohort with amyloid positron emission tomography and behavioral data. Using partial least squares analysis, we identified latent variables relating amyloid or tau pathology with combinations of personality traits, neuropsychiatric symptoms, and cognitive lifestyle. Results In PREVENT-AD, lower neuroticism, neuropsychiatric burden, and higher education were associated with less amyloid deposition (p = .014). Lower neuroticism and neuropsychiatric features, along with higher measures of openness and extraversion, were related to less tau deposition (p = .006). In DIAN, lower neuropsychiatric burden and higher education were also associated with less amyloid (p = .005). The combination of these factors accounted for up to 14% of AD pathology. Conclusions In the preclinical phase of both sporadic and autosomal dominant AD, multiple behavioral features were associated with AD pathology. These results may suggest potential pathways by which multidomain interventions might help delay AD onset or progression