50 research outputs found
On-chip Voltage Regulator– Circuit Design and Automation
Title from PDF of title page viewed May 24, 2021Dissertation advisors: Masud H Chowdhury and Yugyung LeeVitaIncludes bibliographical references (page 106-121)Thesis (Ph.D.)--School of Computing and Engineering. University of Missouri--Kansas City, 2021With the increase of density and complexity of high-performance integrated circuits and systems, including many-core chips and system-on-chip (SoC), it is becoming difficult to meet the power delivery and regulation requirements with off-chip regulators. The off-chip regulators become a less attractive choice because of the higher overheads and complexity imposed by the additional wires, pins, and pads. The increased I2R loss makes it challenging to maintain the integrity of different voltage domains under a lower supply voltage environment in the smaller technology nodes. Fully integrated on-chip voltage regulators have proven to be an effective solution to mitigate power delivery and integrity issues. Two types of regulators are considered as most promising for on-chip implementation: (i) the low-drop-out (LDO) regulator and (ii) the switched-capacitor (SC)regulator. The first part of our research mainly focused on the LDO regulator. Inspired by the recent surge of interest for cap-less voltage regulators, we presented two fully on-chip external capacitor-less low-dropout voltage regulator design.
The second part of this proposal explores the complexity of designing each block of the regulator/analog circuit and proposed a design methodology for analog circuit synthesis using simulation and learning-based approach. As the complexity is increasing day-by-day in an analog circuit, hierarchical flow mostly uses for design automation. In this work, we focused mainly on Circuit-level, one of the significant steps in the flow. We presented a novel, efficient circuit synthesis flow based on simulation and learning-based optimization methods. The proposed methodology has two phases: the learning phase and the evaluation phase. Random forest, a supervised learning is used to reduce the sample points in the design space and iteration number during the learning phase. Additionally, symmetric constraints are used further to reduce the iteration number during the sizing process. We introduced a three-step circuit synthesis flow to automate the analog circuit design. We used H-spice as a simulation tool during the evaluation phase of the proposed methodology. The three most common analog circuits are chosen: single-stage differential amplifier, operational transconductance amplifier, and two-stage differential amplifier to verify the algorithm. The tool is developed in Python, and the technology we used is0.6um. We also verified the optimized result in Cadence Virtuoso.Introduction -- On-chip power delivery system -- Fundamentals of on-chip voltage regulator -- LDO design in 45NM technology -- LDO design in technology -- Analog design automation -- Proposed analog design methodology -- Energy efficient FDSOI and FINFET based power gating circuit using data retention transistor -- Conclusion and future wor
Design of Ternary Logic and Arithmetic Circuits Using GNRFET
Multiple valued logic (MVL) can represent an exponentially higher number of data/information compared to the binary logic for the same number of logic bits. Compared to the conventional and other
emerging device technologies, Graphene Nano Ribbon Field Effect Transistor (GNRFET) appears to be very promising for designing MVL logic gates and arithmetic circuits due to some exceptional electrical properties of the GNRFET, e.g., the ability to control the threshold voltage by changing the width of the GNR. Variation of the threshold voltage is one of the prescribed techniques to achieve multiple voltage levels to implement the MVL circuit. This paper introduces a design approach for ternary logic gates and circuits using MOS-type GNRFET. The designs of basic ternary logic gates like inverters, NAND, NOR, and ternary arithmetic circuits like the ternary decoder, 3:1 multiplexer, and ternary half-adder are demonstrated using GNRFET. A comparative analysis of the GNRFET based ternary logic gates and circuits and those based on the conventional CMOS and CNTFET technologies is performed using delay, total power, and power-delay-product (PDP) as the metrics. The simulation and analysis are performed using the H-SPICE tool with a GNRFET model available on the Nanohub website
Pregnancy with COVID-19: feto-maternal outcome from a tertiary care hospital, Bangladesh
Background: The objective was to determine the maternal and fetal outcomes of pregnant women with COVID-19 infection in the southeast part of Bangladesh.Methods: A prospective observational study was conducted at Chittagong Medical College Hospital (CMCH), Bangladesh, for one year. Pregnant women were divided into suspected and confirmed groups based on the clinical features of COVID-19 and the results of RT-PCR (SARS-CoV2). Outcome measures were maternal death, ICU admission, mechanical ventilation, and stillbirth/neonatal death. The Mann-Whitney U test was applied for between-group comparisons. Binary logistic regression analysis was done for factors affecting feto-maternal outcomes. Results were presented as odds ratios (OR) and 95% confidence intervals (CI).Results: A total of 144 pregnant women (n=144) were included in the study, divided into confirmed (n=71) and suspected (n=73). Complications were more in the confirmed group (p=0.315). Caesarean section was 69% and 64.4% in the confirmed and suspected groups, respectively (p=0.556). Eight women (5.55%) needed ICU admission, five (3.5%) required mechanical ventilation, and five (3.5%) women expired. Fetal distress was seen in 15 (10.41%) pregnancies. Stillbirth or neonatal death and the need for NICU admission were higher for suspected than in confirmed cases. Pregnancies with suspected COVID-19 had 3.91 times (OR: 3.913, 95% CI: 1.398-10.954) higher poor feto-maternal outcome. Unbooked status, COVID-19 test negativity, and use of antivirals were associated with poor feto-maternal outcomes.Conclusions: Pregnancies with COVID-19 were prone to poor feto-maternal outcomes. The study pointed to an improvement in the ANC of pregnant women with COVID-19 in a public hospital like Bangladesh
Reducing unsafe menstrual regulation through medication in Bangladesh
The Population Council and Marie Stopes Bangladesh, in collaboration with the Directorate General of Family Planning and with funding from the World Health Organization, tested the feasibility of introducing menstrual regulation with medication (MRM) in Bangladesh and assessed the acceptability of providing MRM using the combination drug regimen mifepristone and misoprostol in urban and rural public health facilities. As reported in this policy brief, the study demonstrates that it is feasible and safe to introduce MRM in rural and urban public health facilities. Given the choice, almost two-thirds of women preferred MRM to manual vacuum aspiration and women receiving MRM reported being satisfied or very satisfied with their quality of care. The report recommends that the Ministry of Health and Family Welfare and its partners work together to train providers and to procure the medical commodities to introduce MRM as an option for menstrual regulation in health facilities nationwide
Investigation of Multiple-valued Logic Technologies for Beyond-binary Era
Computing technologies are currently based on the binary logic/number system, which is dependent on the
simple on and off switching mechanism of the prevailing transistors. With the exponential increase of data
processing and storage needs, there is a strong push to move to a higher radix logic/number system that
can eradicate or lessen many limitations of the binary system. Anticipated saturation of Moore’s law and
the necessity to increase information density and processing speed in the future micro and nanoelectronic
circuits and systems provide a strong background and motivation for the beyond-binary logic system. In this
review article, different technologies for Multiple-valued-Logic (MVL) devices and the associated prospects
and constraints are discussed. The feasibility of the MVL system in real-world applications rests on resolving
two major challenges: (i) development of an efficient mathematical approach to implement the MVL logic
using available technologies, and (ii) availability of effective synthesis techniques. This review of different
technologies for the MVL system is intended to perform a comprehensive investigation of various MVL technologies and a comparative analysis of the feasible approaches to implement MVL devices, especially ternary
logic
Anticancer activity of grassy Hystrix brachyura bezoar and its mechanisms of action: An in vitro and in vivo based study
Porcupine bezoar (PB) is a calcified undigested material generally found in porcupine’s (Hystrix brachyura)
gastrointestinal tract. The bezoar is traditionally used in South East Asia and Europe for the treatment of cancer,
poisoning, dengue, typhoid, etc. However, limited scientific studies have been performed to verify its anticancer
potential to substantiate its traditional claims in the treatment of cancers. Hence, this study was aimed at investigating the in vitro and in vivo anticancer properties of two grassy PB aqueous extract (PB-A and PB-B) using
A375 cancer cell line and zebrafish model, respectively. This paper presents the first report on in vitro A375 cell
viability assay, apoptosis assay, cell cycle arrest assay, migration assay, invasion assay, qPCR experimental assay
and in vivo anti-angiogenesis assay using the grassy PBs. Experimental findings revealed IC50 value are
26.59 ± 1.37 μg/mL and 30.12 ± 3.25 μg/mL for PB-A and PB-B respectively. PBs showed anti-proliferative
activity with no significant cytotoxic effect on normal human dermal fibroblast (NHDF). PBs were also found to
induce apoptosis via intrinsic pathway and arrest cell cycle at G2/M phase. Additionally, the findings indicated
its ability to debilitate migration and invasion of A375 cells. Further evaluation using embryo zebrafish model
revealed LC50 = 450.0 ± 2.50 μg/mL and 58.7 ± 5.0 μg/mL for PB-A and PB-B which also exerted anti-angiogenesis effect in zebrafish. Moreover, stearic acid, ursodeoxycholic acid and pregnenolone were identified as
possible metabolites that might contribute to the anticancer effect of the both PBs. Overall, this study demonstrated that PB-A and PB-B possess potential in vitro and in vivo anticancer effects which are elicited through
selective cytotoxic effect, induction of apoptosis, inhibition of migration and invasion and anti-angiogenesis.
This study provides scientific evidence that the porcupine bezoar do possess anti-cancer efficacy and further
justifies its traditional utility. However, more experiments with higher vertebrae models are still warranted to
validate its traditional claims as an anticancer agent
Introducing medical MR in Bangladesh: MRM final report
The Population Council Bangladesh, in collaboration with the Directorate General of Family Planning and Marie Stopes Bangladesh, with funding from the World Health Organization and the DFID-supported STEP UP project, conducted an 18-month operations research study from January 2012 to June 2013. This operations research tested the feasibility of introducing menstrual regulation with medication (MRM) in Bangladesh and assessed accessibility of the combination regimen of mifepristone and misoprostol in urban and rural health facilities. Based on this study’s results, the feasibility of introducing MRM services in Bangladesh is clear, and women receiving MRM were satisfied with their overall quality of care. It is imperative that this service be incorporated into the national family planning program for the safety, health, and well-being of Bangladeshi women. The report details some considerations before introducing MRM services nationwide
Effects of a high-dose 24-h infusion of tranexamic acid on death and thromboembolic events in patients with acute gastrointestinal bleeding (HALT-IT): an international randomised, double-blind, placebo-controlled trial
Background: Tranexamic acid reduces surgical bleeding and reduces death due to bleeding in patients with trauma.
Meta-analyses of small trials show that tranexamic acid might decrease deaths from gastrointestinal bleeding. We
aimed to assess the effects of tranexamic acid in patients with gastrointestinal bleeding.
Methods: We did an international, multicentre, randomised, placebo-controlled trial in 164 hospitals in 15 countries.
Patients were enrolled if the responsible clinician was uncertain whether to use tranexamic acid, were aged above the
minimum age considered an adult in their country (either aged 16 years and older or aged 18 years and older), and
had significant (defined as at risk of bleeding to death) upper or lower gastrointestinal bleeding. Patients were
randomly assigned by selection of a numbered treatment pack from a box containing eight packs that were identical
apart from the pack number. Patients received either a loading dose of 1 g tranexamic acid, which was added to
100 mL infusion bag of 0·9% sodium chloride and infused by slow intravenous injection over 10 min, followed by a
maintenance dose of 3 g tranexamic acid added to 1 L of any isotonic intravenous solution and infused at 125 mg/h
for 24 h, or placebo (sodium chloride 0·9%). Patients, caregivers, and those assessing outcomes were masked to
allocation. The primary outcome was death due to bleeding within 5 days of randomisation; analysis excluded patients
who received neither dose of the allocated treatment and those for whom outcome data on death were unavailable.
This trial was registered with Current Controlled Trials, ISRCTN11225767, and ClinicalTrials.gov, NCT01658124.
Findings: Between July 4, 2013, and June 21, 2019, we randomly allocated 12 009 patients to receive tranexamic acid
(5994, 49·9%) or matching placebo (6015, 50·1%), of whom 11 952 (99·5%) received the first dose of the allocated
treatment. Death due to bleeding within 5 days of randomisation occurred in 222 (4%) of 5956 patients in the
tranexamic acid group and in 226 (4%) of 5981 patients in the placebo group (risk ratio [RR] 0·99, 95% CI 0·82–1·18).
Arterial thromboembolic events (myocardial infarction or stroke) were similar in the tranexamic acid group and
placebo group (42 [0·7%] of 5952 vs 46 [0·8%] of 5977; 0·92; 0·60 to 1·39). Venous thromboembolic events (deep vein
thrombosis or pulmonary embolism) were higher in tranexamic acid group than in the placebo group (48 [0·8%] of
5952 vs 26 [0·4%] of 5977; RR 1·85; 95% CI 1·15 to 2·98).
Interpretation: We found that tranexamic acid did not reduce death from gastrointestinal bleeding. On the basis of our
results, tranexamic acid should not be used for the treatment of gastrointestinal bleeding outside the context of a
randomised trial
Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017
A double burden of malnutrition occurs when individuals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4% (62.3 (55.1–70.8) million) to 6.4% (58.3 (47.6–70.7) million), but is predicted to remain above the World Health Organization’s Global Nutrition Target of <5% in over half of LMICs by 2025. Prevalence of overweight increased from 5.2% (30 (22.8–38.5) million) in 2000 to 6.0% (55.5 (44.8–67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic