DROUGHT MITIGATION THROUGH HYDROGEL APPLICATION IN RICE (Oryza sativa L.) CULTIVATION

Sustainability in irrigation is an essential step towards responsible water consumption. In recent years, many studies have sketched climate-resilient agricultural practices to fight drought and uncertain rainfall patterns. Major rain-fed crops such as paddy and wheat require aid when there are abnormal dry spells. To mitigate the loss of crops from such events, superabsorbent polymers can be used. Soils amended with hydrogel or Superabsorbent polymer (SAP) retain moisture during drought to prevent loss of water through evaporation and percolation. This allows the crop to grow with less shock from drought. This study compares rice (Oryza sativa L.) growth rate under application (treatment groups) and non-application (control groups) of hydrogel, considering their high-water requirement. NDLR07 (recently developed) and BPT5204 (local variety) rice varieties were chosen for the current study. Randomized controlled trials were performed for each variety on a control group (NC & BC) and 3 treatment groups with 20% (NT20 & BT20), 40% (NT40 & BT40), and 60% (NT60 & BT60) deficit water supplies respectively. N, T, C refers to seed type, treatment group, control group respectively. Intermittent drought condition was imposed for 14 days to assess the resilience of crops. The water retention capacity of the sandy loam soil was better for treatment groups by 20% than control groups even at an average temperature of 40 ℃. Treatment groups continued growing through the drought phase and after, while control groups showed stagnation. Among the tested treatment groups, NT20 had the highest growth among all trials. The results of the study suggested that hydrogel application can help to combat droughts and thereby contribute to sustainable agricultural production by restricting the involvement of climate changes

Design of time-predictable architecture and DDR memory bank allocation for COTS multi-cores

An increasing trend in the chip manufacturing industry is the adoption of multi-core processors. This overwhelming trend of using Commercial Off-The-Shelf (COTS) multi-core processors has benefited most of the industries that require high computing performance at low power and greater efficiency. However, real-time systems are those systems where not only the correctness of execution is critical but also the time at which this execution occurs is equally critical. The multi-core processors offer a very high computing performance owing to the increased number of processing cores, but do not guarantee a predictable Worst-Case Execution Time (WCET), which is defined as the maximum time an application can take to execute on a given hardware. This uncertainty in the estimation of the WCET arises from a multitude of challenges which are inherently present in the multi-core architecture. As a first step, these challenges are identified and then further focused on exploring a representative multi-core processor. The primary challenges identified in this thesis are related to the sharing of hardware components in the multi-core architecture which includes the Double Data Rate (DDR) memory and its controller, caches and system bus. A detailed architecture analyses of a COTS multi-core is performed along with a series of experiments which help to understand and quantify the unpredictability arising due to the sharing of hardware resources. This study not only helps to understand the challenges but also the severity of each challenge. As a next step, to mitigate this primary challenge of shared memory subsystem in the multi-cores, a novel hybrid System On Chip (SoC) architecture is proposed which couples COTS multi-core with a Field Programmable Gate Array (FPGA). The proposed architecture is designed on the Xilinx Zynq 706 platform. The key feature of this proposed architecture is that the shared hardware components which causes the unpredictability inside the multi-core are disabled and are designed separately on the FPGA to aid predictable execution of applications. The thesis specifically focuses on one of the components in the shared memory subsystem, which is the DDR memory and its controller. A predictable memory controller is designed for this architecture to show that the ARM A9 multi-core can be coupled with the custom designed memory controller on the FPGA. The thesis also shows that the latency on the FPGA can be bounded theoretically and hence this architecture aids in predictable execution of applications. As a final step, the thesis focuses on the DDR memory and its controller and address one of the key challenges which is DDR memory bank allocation to the cores. Although the execution time of an application can be bounded in a predictable memory controller, it is important to allocate only the required number of banks to the cores such that the worst-case execution time requirement of the application is satisfied. This allocation determines the utilization of the DDR memory. Hence, it is important that the number of banks should not be overloaded for any application. The thesis specifically focus on two scenarios. One, where the banks of the DDR are shared by the cores and the other where the banks are private to the cores. In each of the scenario, an optimal bank allocation policy is presented. The key significance of this contribution is the fact that the algorithms presented are optimal and always return the best allocation whenever feasible. Thus, in this dissertation an outline to use the multi-cores in a predictable manner for real-time systems has been provided.Doctor of Philosoph

Charge injection in vertically stacked multi-layer black phosphorus

The efficiency of any electronic device is highly reliant on the charge-injection efficiency at the electrical contact and semiconductor interface. Black phosphorus (BP), a layered and highly anisotropic material is attractive for a variety of electronic and optoelectronic applications including vertically stacked devices with distinct top and bottom electrodes. This makes it imperative to ascertain the influence of contact materials on the charge injection in the out-of-plane configuration. Here, we explore four different contact materials (aluminium, ITO, gold and platinum) chosen based on their work functions relative to the chemical potential of BP. By monitoring the current-voltage characteristics in the out-of-plane direction, conclusions are drawn regarding the charge injection capabilities of these contact materials providing the base knowledge to design efficient BP based stacked devices

Disrupting MLV integrase:BET protein interaction biases integration into quiescent chromatin and delays but does not eliminate tumor activation in a MYC/Runx2 mouse model.

Murine leukemia virus (MLV) integrase (IN) lacking the C-terminal tail peptide (TP) loses its interaction with the host bromodomain and extraterminal (BET) proteins and displays decreased integration at promoter/enhancers and transcriptional start sites/CpG islands. MLV lacking the IN TP via an altered open reading frame was used to infect tumorigenesis mouse model (MYC/Runx2) animals to observe integration patterns and phenotypic effects, but viral passage resulted in the restoration of the IN TP through small deletions. Mice subsequently infected with an MLV IN lacking the TP coding sequence (TP-) showed an improved median survival by 15 days compared to wild type (WT) MLV infection. Recombination with polytropic endogenous retrovirus (ERV), Pmv20, was identified in seven mice displaying both fast and slow tumorigenesis, highlighting the strong selection within the mouse to maintain the full-length IN protein. Mapping the genomic locations of MLV in tumors from an infected mouse with no observed recombination with ERVs, TP-16, showed fewer integrations at TSS and CpG islands, compared to integrations observed in WT tumors. However, this mouse succumbed to the tumor in relatively rapid fashion (34 days). Analysis of the top copy number integrants in the TP-16 tumor revealed their proximity to known MLV common insertion site genes while maintaining the MLV IN TP- genotype. Furthermore, integration mapping in K562 cells revealed an insertion preference of MLV IN TP- within chromatin profile states associated with weakly transcribed heterochromatin with fewer integrations at histone marks associated with BET proteins (H3K4me1/2/3, and H3K27Ac). While MLV IN TP- showed a decreased overall rate of tumorigenesis compared to WT virus in the MYC/Runx2 model, MLV integration still occurred at regions associated with oncogenic driver genes independently from the influence of BET proteins, either stochastically or through trans-complementation by functional endogenous Gag-Pol protein