Ultra-low-power SRAM design in high variability advanced CMOS

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 163-181).Embedded SRAMs are a critical component in modern digital systems, and their role is preferentially increasing. As a result, SRAMs strongly impact the overall power, performance, and area, and, in order to manage these severely constrained trade-offs, they must be specially designed for target applications. Highly energy-constrained systems (e.g. implantable biomedical devices, multimedia handsets, etc.) are an important class of applications driving ultra-low-power SRAMs. This thesis analyzes the energy of an SRAM sub-array. Since supply- and threshold-voltage have a strong effect, targets for these are established in order to optimize energy. Despite the heavy emphasis on leakage-energy, analysis of a high-density 256x256 sub-array in 45nm LP CMOS points to two necessary optimizations: (1) aggressive supply-voltage reduction (in addition to Vt elevation), and (2) performance enhancement. Important SRAM metrics, including read/write/hold-margin and read-current, are also investigated to identify trade-offs of these optimizations. Based on the need to lower supply-voltage, a 0.35V 256kb SRAM is demonstrated in 65nm LP CMOS. It uses an 8T bit-cell with peripheral circuit-assists to improve write-margin and bit-line leakage. Additionally, redundancy, to manage the increasing impact of variability in the periphery, is proposed to improve the area-offset trade-off of sense-amplifiers, demonstrating promise for highly advanced technology nodes. Based on the need to improve performance, which is limited by density constraints, a 64kb SRAM, using an offset-compensating sense-amplifier, is demonstrated in 45nm LP CMOS with high-density 0.25[mu]m2 bit-cells.(cont.) The sense-amplifier is regenerative, but non -strobed, overcoming timing uncertainties limiting performance, and it is single-ended, for compatibility with 8T cells. Compared to a conventional strobed sense-amplifier, it achieves 34% improvement in worst-case access-time and 4x improvement in the standard deviation of the access-time.by Naveen Verma.Ph.D

An Online KAP Study to Access Contraceptive Use Among Reproductive Females in North-Western India

INTRODUCTION: The use of contraceptives has been practiced since thousand of years and if used correctly can lead to birth control. AIM: To assess the knowledge, attitude and practices of contraceptive of reproductive females aged 18 years and above.MATERIALS AND METHOD: The present study was cross-sectional in nature and included married females above 18 years of age were asked to fill up an online questionnaire, divided into 4 sections and containing 17 questions. After application of descriptive statistics, the multivariate logistic regression and Pearson’s correlation was applied. p value was significant when it was ≤0.05RESULTS: Most respondents has poor knowledge (54.5%) of contraceptives with the most preferred method of contraception being OCP (36.3%) closely followed by condoms (36.1%). Awareness regarding emergency use on contraceptives was mostly seen to be poor (43.9%). The most common method used for contraception was condoms (49.7%%), followed by IUDs (15.6%),Injectables (14.3%) and OCPs(12.7%). Only a few (5.3%) did not practice any method for contraception and 2.4% underwent sterilization. the multivariate logistic regression revealed a significant relation (p=0.03) while and Pearson’s correlation (p=0.76) revealed a strong association. CONCLUSION: There is a need to educate females more about the various methods of contraception to promote their reproductive healt

INFLUENCE OF MEDIA GELLING AGENTS ON ROOT BIOMASS AND IN VITRO VA-MYCORRfflZAL SYMBIOSIS OF CARROT WITH GIGASPORA MARGARITA

An in vitro study with Ri-TDNA transformed roots of carrot  (Daucus carota) was carried out  to evaluate  the role of macro-elements contributed as impurities in  the gelling agent (phytagel) over and above  those present  in the minimal (M) medium. Production of root biomass was taken as a measure to quantify the influence of macro-elements added to the minimal medium. The levels of phosphorus when adjusted to 1.19 mg/1 and 1.09 mg/l, lead to dry root biomass production at par with the control. Attempts made to lower the amount of impurities in phytagel by de-ionization using different alkalies, proved NaOH to give the best results in terms of relatively high amount of root biomass. In an in vitro dual culture system with carrot as host and Gigaspora margarita as the vesicular-arbuscular mycorrhizal fungus, phytagel impurities helped to produce maximum number of infection units and auxiliary cells when phytagel was added to the minimal medium.Key words:    Agrobacterium    rhiiogenesfDaucus    caro/a/Gelling    agents/diaspora    margarita/Macro- elements/Vesicular-arbuscular mycorrhiza/Transformed roots

Analysis of different temporal graph neural network configurations on dynamic graphs

In recent years, there has been an increasing interest in the use of graph neural networks (GNNs) for analyzing dynamic graphs, which are graphs that evolve over time. However, there is still a lack of understanding of how different temporal graph neural network (TGNs) configurations can impact the accuracy of predictions on dynamic graphs. Moreover, the hunt for benchmark datasets for these TGNs models is still ongoing. Up until recently, Pytorch Geometric Temporal came up with a few benchmark datasets but most of these datasets have not been analyzed with different TGN models to establish the state-of-the-art. Therefore, this project aims to address this gap in the literature by performing a qualitative analysis of spatial-temporal dependence structure learning on dynamic graphs, as well as a comparative study of the effectiveness of selected TGNs on node and edge prediction tasks. Additionally, an extensive ablation study will be conducted on different variants of the best-performing TGN to identify the key factors contributing to its performance. By achieving these objectives, this project will provide valuable insights into the design and optimization of TGNs for dynamic graph analysis, with potential applications in areas such as disease spread prediction, social network analysis, traffic prediction, and more. Moreover, an attempt is made to convert snapshot-based data to the event-based dataset and make it compatible with the SOTA model namely TGN to perform node regression task

Optical properties of Yb3+ doped ZnO/MgO nanocomposites

[EN] Yb3þ doped ZnO/MgO nanocomposite were prepared by combustion synthesis method. The samples were further heated to 1000 °C to improve their crystallinity and photoluminescent efficiency. The concentrations of Yb3þ and Mg2þ were varied between 1–2% and 5–70% respectively in prepared samples. The nano-powders were characterized by Scanning Electron Microscopy and X-ray Diffraction for morphology and structural determination. XRD studies have revealed the wurtzite structure for MgxZn1"xO for Mg concentrations below 30%. Higher concentrations of Mg results in Yb3þ doped ZnO/ MgO nanocomposite containing three phases; the wurzite hexagonal phase typical of ZnO, the cubic phase of MgO and a small amount of cubic Yb2O3 phase. As expected, the amount of cubic phase in nanopowders increased with the increase of Mg concentration in ZnO. The crystallite size of ZnO/MgO composites decreased from 55 nm to 30 nm with increase of Mg content. SEM images of Yb3þ doped ZnO/MgO nanocomposite with higher Mg content (450%) showed clearly distinct hexagonal and cubical shaped nano-particles. Photoluminescent emission showed a broad band in the range (435 nm to 700 nm). Pure ZnO nano-phosphor showed an emission peak around 545 nm, which is blue shifted with Mg content. The photoluminescence intensity increased with increase of Mg content in ZnO and it became maximum with 30% Mg concentration. Time resolved decay curves of photoluminescence indicated decay time in microsecond time scaleThis work was supported by Ministerio de Economia y Competitividad (ENE2013-46624-C4-4-R), Generalitat Valenciana (PROMETEUS-II/2014/044) and the European Commission through NanoCIS project (FP7-PEOPLE-2010-IRSES ref. 269279).Marí, B.; Singh, KC.; Verma, N.; Jindal, J. (2016). Optical properties of Yb3+ doped ZnO/MgO nanocomposites. Ceramics International. 42(11):13018-13023. https://doi.org/10.1016/j.ceramint.2016.05.079S1301813023421

Sleep Deprivation Enhances False Memory on the Deese-Roediger-McDermott (DRM) Task

False memories are memories that people report to be true with high confidence, even though they had never encountered the fact behind the memory in reality. Such memories possess strong semantic association with already existing encoded memories which hence appear to be familiar. Sleep is known to provide optimal conditions for the consolidation of long-term memories whereas the deprivation of sleep is known to hinder memory’s consolidation process. The role of sleep in the formation and enhancement of false memories was tested. The Deese-Roediger-McDermott (DRM) task was used to induce false memory in thirty-nine male volunteers who either slept or remained awake following learning. Following a night of recovery sleep both groups returned for retrieval of memory. It was found that sleep deprivation in comparison to sleep led to higher false memory

Influence of Media Gelling Agents on Root Biomass and in Vitro Va-mycorrfflzal Symbiosis of Carrot with Gigaspora Margarita

An in vitro study with Ri-TDNA transformed roots of carrot (Daucus carota) was carried out to evaluate the role of macro-elements contributed as impurities in the gelling agent (phytagel) over and above those present in the minimal (M) medium. Production of root biomass was taken as a measure to quantify the influence of macro-elements added to the minimal medium. The levels of phosphorus when adjusted to 1.19 mg/1 and 1.09 mg/l, lead to dry root biomass production at par with the control. Attempts made to lower the amount of impurities in phytagel by de-ionization using different alkalies, proved NaOH to give the best results in terms of relatively high amount of root biomass. In an in vitro dual culture system with carrot as host and Gigaspora margarita as the vesicular-arbuscular mycorrhizal fungus, phytagel impurities helped to produce maximum number of infection units and auxiliary cells when phytagel was added to the minimal medium

Luminescence Properties of CaAl2O4:Eu3+, Gd3+ Phosphors Synthesized by Combustion Synthesis Method

[EN] CaAl2O4:Eu3+ (1 mol.%) co-doped with varying concentration of Gd3+ (1, 2, 5, and 10 mol.%) were prepared by combustion synthesis method at 600 C and further annealed at 1000 ºC. All the compositions were investigated for their structural and photoluminescence properties. It was observed that both states of europium i.e. Eu3+ and Eu2+ were present and ratio of these states changes on heating at 1000 ºC. The materials synthesized at 600 ºC showed high intense peak around 440 nm due to presence of Eu2+ and less intense peaks in the red region which were due to presence of Eu3+. On annealing the compounds at 1000 ºC, intensity of peak around 440 nm decreases and intensity of peaks in the red region increases significantly. The 5D0 !7 F3 transition due to Eu3+ at 657 nm appears as the highest intensity peak. All co-doped samples annealed at 1000 ºC showed the higher intensity than the mono doped sample which is due to energy transfer from the Gd3+ to Eu3+. The second rare-earth ion (Gd3+) acts as sensitizer and enhances the photoluminescence intensity. The X-ray diffraction spectra reveal the monoclinic phase of CaAl2O4 in all the samples which showed that Eu3+ and Gd3+ do not change the crystalline structure of calcium aluminate.This work was supported by the Generalitat Valenciana through grant PROMETEUS 2009/2013 and the European Commission through Nano CIS project (FP7-PEOPLE-2010-IRSES ref. 269279).This work was supported by the Generalitat Valenciana through grant PROMETEUS 2009/2013 and the European Commission through Nano CIS project (FP7- PEOPLE-2010-IRSES ref. 269279).Verma, N.; Singh, K.; Marí, B.; Mollar García, MA.; Jindal, J. (2017). Luminescence Properties of CaAl2O4:Eu3+, Gd3+ Phosphors Synthesized by Combustion Synthesis Method. Acta Physica Polonica A. 132(4):1261-1264. https://doi.org/10.12693/APhysPolA.132.1261S12611264132

Luminescence properties of the Eu2+ /Eu3 + activated Barium aluminate phosphors with varies Gd3+ concentration

This is an Accepted Manuscript of an article published by Taylor & Francis in Transactions of the Indian Ceramic Society on 2015, available online: http://www.tandfonline.com/10.1080/0371750X.2015.1082932[EN] BaAl2O4:Eu2(+)/Eu3(+) (1mol %) co-doped with varying concentrations of Gd3(+) (1, 2, 5 and 10mol%) were prepared by combustion synthesis method at 600 degrees C. All the compositions were investigated for their structural and photoluminescence properties. Samples prepared in open atmosphere showed the presence of both Eu3(+) and Eu2(+) states which indicates the reduction of Eu3(+) to Eu2(+) during the preparation of these compounds. The prepared materials at 600 degrees C showed high intense broad peaks around 498nm corresponding to Eu2(+) and small peaks in the red region which are attributed to the presence of Eu3(+). In the 1000 degrees C annealed compounds, the intensity of the peak at 498nm got increased. The intensity of this broad band for BaAl2O4:Eu2(+)/Eu3(+)(1mol%):Gd3(+)(1mol%) was three times than that of BaAl2O4:Eu2(+)/Eu3(+)(1mol%). Thus second rare earth ion (Gd3(+)) acted as a good sensitizer and enhanced the photoluminescence intensity. The XRD spectra revealed the presence of hexagonal phase of BaAl2O4 as main phase and a small amount of a mixed phase Ba O! 6.6 Al2O3. Doping of Eu3(+), Gd3(+) did not change the crystalline structure of barium aluminate (BaAl2O4).This work was supported by the Generalitat Valenciana through grant PROMETEUS 2009/2013 and the European Commission through Nano CIS project (FP7-PEOPLE2010-IRSES ref. 269279).Marí, B.; Singh, K.; Verma, N.; Mollar García, MA.; Jindal, J. (2015). Luminescence properties of the Eu2+ /Eu3 + activated Barium aluminate phosphors with varies Gd3+ concentration. Transactions of the Indian Ceramic Society. 74(3):157-161. https://doi.org/10.1080/0371750X.2015.1082932S15716174