Voltage-to-Time Converter for High-Speed Time-Based Analog-to-Digital Converters

In modern complementary metal oxide semiconductor (CMOS) technologies, the supply voltage scales faster than the threshold voltage (Vth) of the transistors in successive smaller nodes. Moreover, the intrinsic gain of the transistors diminishes as well. Consequently, these issues increase the difficulty of designing higher speed and larger resolution analog-to-digital converters (ADCs) employing voltage-domain ADC architectures. Nevertheless, smaller transistor dimensions in state-of-the-art CMOS technologies leads to reduced capacitance, resulting in lower gate delays. Therefore, it becomes beneficial to first convert an input voltage to a 'time signal' using a voltage-to-time converter (VTC), instead of directly converting it into a digital output. This 'time-signal' could then be converted to a digital output through a time-to-digital converter (TDC) for complete analog-to-digital conversion. However, the overall performance of such an ADC will still be limited to the performance level of the voltage-to-time conversion process. Hence, this thesis presents the design of a linear VTC for a high-speed time-based ADC in 28 nm CMOS process. The proposed VTC consists of a sample-and-hold (S/H) circuit, a ramp generator and a comparator to perform the conversion of the input signal from the voltage to the time domain. Larger linearity is attained by integrating a constant current (with high output impedance) over a capacitor, generating a linear ramp. The VTC operates at 256 MSPS consuming 1.3 mW from 1 V supply with a full-scale 1 V pk-pk differential input signal, while achieving a time-domain output signal with a spurious-free-dynamic-range (SFDR) of 77 dB and a signal-to-noise-and-distortion ratio (SNDR) of 56 dB at close to Nyquist frequency (f = 126.5 MHz). The proposed VTC attains an output range of 2.7 ns, which is the highest linear output range for a VTC at this speed, published to date

Diffusion tensor imaging for ruptured cerebral arteriovenous malformation

Non-ruptured arteriovenous malformations (AVMs) rarely cause tract disruption. Few studies have described how ruptured AVMs influence white matter (WM) tract morphology. We reviewed consecutive AVM cases treated at a tertiary care hospital where diffusion tensor imaging (DTI) tractography was obtained preoperatively. DTI was performed using the Synaptive Plan (Synaptive Medical Inc., Toronto, Canada). Quality control was performed by clinical application specialist. Perinidal fractional anisotropy (FA) value of corticospinal tracts (CST) was obtained. A reference FA value was obtained from the corresponding area on the contralateral side. Images were evaluated by a consultant neuroradiologist. Radiological findings were correlated with clinical findings. White matter morphology was described by a consultant neuroradiologist. All three cases included in the study had a history of haemorrhage in the past. Two patients had disruption of CST and presented with a significant neurological deficit. In one patient FA value of CST around the nidus was comparable to the contralateral side and did not show any neurological deficit. DTI integrated neuronavigation was used to plan the trajectory and complete resection of the AVM with excellent postoperative recovery

A study protocol for an mHealth, multi-centre randomized control trial to promote use of postpartum contraception amongst rural women in Punjab, Pakistan

Background: Provision of family planning services during the immediate post-partum phase is considered effective and cost-efficient for promoting healthy timing and spacing of pregnancies. This research aims to test the effectiveness of mobile phone-based interventions in promoting use of postpartum contraception. Moreover, it will also test the non-inferiority of text and voice messages compared to interactive phone-based counselling.Methods: A three-arm, 10-month, multicentre, randomized controlled trial will be conducted at 15 social franchise (SF) health facilities in Punjab province of Pakistan. Pregnant women aged 15-44 years who are in their first or second trimester and have a mobile phone for their own use will be eligible to participate in this study. The participants will be randomly allocated to one of three study arms: a) voice and text messages; b) interactive telephone-based counselling; or c) control arm (no additional phone-based support). The intervention counselling module will be developed based on the Integrated Behaviour Model which was recently adapted, and tested for the family planning context in Pakistan. It will broadly cover birth-preparedness, importance of birth spacing, and postnatal care. The phone-based intervention aims to improve women\u27s ability to use contraception by providing them with information about a range of methods, access to family planning methods through outlets such as Suraj SF providers, connecting them with MSS field health educators to help them reach the centres, motivation by re-enforcing the benefits of contraceptive use on women\u27s quality of life, and dispelling myths and misconceptions about modern contraceptive methods. Risk differences will be used as the measure of effect of the intervention on the outcomes.Discussion: The study findings will highlight effectiveness of mobile phone in raising awareness of maternal health and contraception, which in turn, is expected to be translated into increased proportion of: at least four antenatal visits, skilled birth or institutional delivery, postpartum contraceptive use, postnatal check-up, child immunization, and breastfeeding. Moreover, if the text and voice messages approach is proven to be non-inferior to interactive calls, it will provide evidence to making promotion of healthcare less resource intensive, and thereby contribute in improving the efficiency of the healthcare system.Trial registration: This trial was prospectively registered with the Clinical Trials registry ( NCT03612518 ) on August 2nd, 2018

Resolution of symptomatic secondary empty sella syndrome following lumbar-peritoneal shunt.

Background: Post‑surgical empty sella is related to the removal of pituitary tumors either from the transcranial or transphenoidal route, rendering diaphragma sellae incompetent at the end of the procedure. This subsequently leads to herniation of the third ventricle and optic apparatus into the empty sella. Studies have shown that in 50% of the cases, individuals with primary and secondary empty sella syndrome have developed defects in the visual fields. Benign increased intracranial pressure, cerebrospinal rhinorrhea, papilledema, and abnormalities affecting visual acuity may also occur as a result of empty sella. Case Description: This case report discusses a rare treatment option for the symptomatic secondary empty sella syndrome. Patient underwent lumbar drain placement and that resulted in astonishingly significant improvement in vision. Keeping in view the beneficial effect of lumbar drain, lumbar–peritoneal (LP) shunt was inserted which showed drastic improvement in vision. Conclusion: The surgical outcome of symptomatic cases of ESS is favorable. Various common surgical options were reported in literature; however, we have discussed an unconventional surgical option with an impressive outcome

Does lipocalin-2 affect metabolic syndrome in hepatic infections?

Background and objective: Lipocalin-2 (LCN-2) is an adipokine that plays a protective role in various inflammatory disorders and regulates innate immune response to acute and chronic infections. However, scant information is available regarding the relationship between serum LCN-2 levels and type 2 diabetes mellitus (T2DM) occurring concurrently with chronic hepatic infections. The present study sought to investigate the association of LCN-2 with T2DM patients with hepatic infections.Methods: The association of LCN-2 with T2DM, hepatic steatosis, and inflammation was tested in 37 non-T2DM noninfectious individuals (group A, control group) and 55 age-matched patients with T2DM and chronic infection (group B). Anthropometric data were measured and the body-fat percentage was calculated using bioelectrical impedance analysis (BIA). Hemoglobin (Hb), fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), liver function enzymes (LFEs), lipid profile, and total leukocyte count (TLC) were measured. Serum LCN-2 levels were measured using a commercially available sandwich enzyme-linked immunosorbent assay method.Results: Levels of LCN-2 were significantly elevated in group B (1896.90 ± 73.13 ng/ml) versus control group A (263.58 ± 15.66 ng/mL; p\u3c0.001). LCN-2 correlated moderately with alanine aminotransferase (ALT) (r=0.369), alkaline phosphatase ALP (r=0.419), and HbA1c (r=0.341) (p\u3c0.01). All correlations were lost when adjusted for the presence of hepatitis, indicating that liver infection exacerbates insulin resistance.Conclusion: Based on our findings, circulating LCN-2 is elevated in T2DM subjects with hepatitis B co-infection and may contribute towards deranged inflammatory response

Outcomes of post-neurosurgical ventriculostomy-associated infections

Background: Ventriculostomy-associated infection (VAI) is a major concern to physicians. Limited studies have looked at the outcomes of external ventricular drain (EVD) infection and predictors of unfavorable outcomes. In this study, we assessed the outcomes of EVD infection and predictors of unfavorable outcomes.Methods: This was a retrospective medical chart review, conducted at the Aga Khan University Hospital. All the patients irrespective of age and gender, fulfilling the diagnostic criteria of VAI were included. Patients with preexisting bacterial meningitis or ventriculitis were excluded from the study. Outcome assessment was based on Glasgow outcome scale (GOS) at 1 and 3 months after procedure. Other outcomes included 30-day mortality and total length of hospital stay.Results: We included 256 patients in the study. 66 patients (25.8%) developed VAI. EVD was the primary procedure in 21 (31.8%) cases. Most patients, 24 (36.4%), had EVD as a secondary procedure for tumor surgery. Median interval between EVD placement and diagnosis of infection was 3 days. Mean length of stay in VAI patients was 31.85 ± 20.53 days. Seven patients required ICU care. Ten patients (15.2%) expired during hospital stay or within 30 days of discharge and further four had GOS of 2 or 3. A total of 52 patients had a favorable outcome after 6 months.Conclusions: Rate of VAI in this cohort was high. VAI is associated with increased morbidity, mortality, and prolonged hospital stay

Knowledge, attitudes and practices towards COVID-19 among Pakistani residents: Information access and low literacy vulnerabilities

Background: Coronavirus disease (COVID-19) has accentuated the need for speedy access to information. Digital divide and socio-demographic disparity create an information hiatus and therefore unhealthy practices with regard to dealing with COVID-19, particularly in low- and middle-income countries.Aims: We assessed knowledge, attitudes, practices and their determinants regarding COVID-19 in Pakistan during March-April 2020.Methods: 905 adults ≥18 years (males and females) participated: 403 from a web-based survey; 365 from an urban survey; and 137 from a rural survey. Frequency of adequate knowledge, attitudes and practices for the three populations was determined based on available global guidelines. Multivariable logistic regression analysis determined factors of adequacy of knowledge, attitudes, practices, and association of knowledge with attitudes and practices.Results: Mean age of the participants was 33.5 (+ SD 11.1) years, 51% were females. More females and young adults (18-30 years) participated in the web-based survey. The urban survey and web-based survey participants had significantly higher adequate knowledge (2-7 times) and practices (4-5 times) towards COVID-19. Adequate knowledge had a significant influence on healthy attitudes and practices for COVID-19, after adjustment for covariates. Overall, two-thirds of the population had high levels of fear about COVID-19, which was highest among the rural survey population.Conclusion: Substantial gaps exist in adequate knowledge, attitudes and practices, particularly among rural populations, and underscores the variation in access to information according to level of education and access to the internet. Thus, a comprehensive, contextually congruent awareness raising strategy is urgently needed to confront COVID-19 among these populations

Does courtesy bias affect how clients report on objective and subjective measures of family planning service quality? A comparison between facility- and home-based interviews

Purpose: Despite a general understanding that exit interviews being conducted at service providers\u27 facilities may influence clients\u27 responses favorably to health professionals, there is very little evidence available that demonstrates the extent to which this problem exists. This study aimed at assessing and comparing clients\u27 perceptions of the quality of family planning services and their satisfaction levels between facility- and home-based interviews.Methods: A cross-sectional survey was conducted among clients receiving family planning services across three service delivery channels - nongovernmental organization (NGO) clinics, social franchise (SF) centers, and outreach camps. The survey took place from December 2015 to January 2016 in 70 districts across all four provinces of Pakistan. A total of 2,807 clients were interviewed, of whom 1,404 clients were interviewed at health facilities after receiving services and 1,403 were interviewed at their homes within 3 days of method uptake.Results: Overall, we found no significant differences between the characteristics of study participants interviewed at health facilities or at home. The findings suggested that experiences reported in exit surveys at facilities were strongly biased positively. This was true for both experiential (service quality) and perception-based (satisfaction) questions in the context of SF centers, while at NGO clinics the interview location only affected clients\u27 responses regarding service quality. However, in outreach settings, clients are more likely to share bad experiences in exit interviews than in home-based interviews on objectively asked questions (service quality).Conclusion: Our study indicates signs of courtesy bias and possibly the Hawthorne effect in exit interviews. Program implementers could opt for home-based interviews for women receiving services at NGO clinics or SF center, whereas exit interviews could be used in outreach settings

Geochemistry and Petrographical Study of Langrial Iron Ore from Tethyan Hazara Area Pakistan, with Emphasis on its Economic Characterization and Depositional Setting

The Langrial iron ore of Hazara area has been studied in detail at five locations for its geochemistry, genesis and economic potential investigations. A maximum of thirty samples were collected from iron ore bodies at different localities of Bagnotar, Danna Noral, Tatti Maira, Najafpur and Jabri for detailed analysis. The thick bedded iron ore has been deposited in the form of unconformity at Cretaceous-Paleocene boundary sandwiched between Kawagarh and Hangu formations (i.e. Cretaceous-Paleocene boundary). At the base of Hangu Formation variable thickness of these lateritic beds spread throughout the Hazara and Kohat-Potwar plateau. These iron ore bodies are studied by X-Ray Diffraction technique (XRD), X-ray Fluorescence Spectrometry (XRF), Petrographic studies and Scanning Electron Microscope (SEM). This XRD analysis indicated that iron bearing minerals are hematite with intercalation of chamosite, quartz and a proportion of impurities having albite, illite-montmorillonite, kaolinite, calcite, dolomite and ankerite. The X-ray Fluorescence (XRF) results show that total Fe2O3 ranges from 30 to 50% having high silica, while alumina to silica ratio is less than 1. The petroghraphic studies revealed concentration of Langrial iron beds as oolitic hematite nodule having variable concentric to composite structure. A high energy shallow marine depositional environment was deduced for Langrial iron ore, as inferred from SEM and mineralogical data. The overall results show that Langrial iron ore is a low-grade iron ore with average Fe2O3 of 52%, and can be upgraded by applying modern mining techniques to fulfill steel requirements of the country

What influences family planning in rural Pakistan: Franchised service provider and community health worker perspective

Background: Pakistan has a low modern contraceptive prevalence rate, 26%, leading family planning (FP) programmes to explore partnerships with local private providers to improve access to quality FP services. This study aims to understand the socio-cultural and organizational factors that influence delivery of quality family planning services. Methods: This qualitative study was conducted with private service providers and community health workers (CHW) in Marie Stopes Society\u27s (MSS) social franchise network. A total of 31 providers and 28 CHWs from Sindh, Punjab, and Khyber Pakhtunkhwa provinces of Pakistan were purposively selected for in-depth interviews. The study used thematic content analysis to understand providers\u27 and health workers\u27 perspectives of family planning service provision. Results: This study found that normative environment, propagation of myths and misconceptions, and health concerns remain major barriers to service provision in rural communities. Findings showed that CHWs were instrumental in increasing awareness and positive attitudes towards family planning in the catchment areas. Moreover, social franchising was effective in increasing access to high-quality, subsidised family planning services amongst economically marginalised and low-awareness communities. Providers and health workers expressed satisfaction with the franchising approach, and revealed that being part of this network substantially increased their client volume and ability to serve poorer segments of the population. Conclusion: The study found that franchising private service providers in rural areas enhances their ability to serve clients, and when coupled with demand-generation elements, such as vouchers and community health workers, it substantially increases their client volume. Albeit effective, the franchising approach currently lacks the element of long-term service provision at the current scale, and may require further strategizing by the franchisor. Moreover, alternate strategies should be explored to ensure continued provision of FP services without vouchers and CHWs