N—H⋯N hydrogen bonding in 4,6-diphenyl-2-pyrimidinylamine isolated from the plant Justicia secunda (Acanthaceae)

The title compound, C₁₆H₁₃N₃, isolated from Justicia secunda (Acanthaceae), comprises two molecules (which differ slightly in conformation) in the asymmetric unit of space group P\overline 1. Intermolecular Namino-H...Npyrm interactions (Npyrm is a pyrimidine ring N atom) involve only one of the two donor amino H atoms and pyrimidine N atoms per molecule, forming dimeric units via R²₂(8) rings, with N...N distances of 3.058 (2) and 3.106 (3) Å, and N-H...N angles of 172.7 (18) and 175.8 (17)°. The dimers are linked by C-H...π(arene) contacts, with an H...centroid distance of 2.77 Å and a C-H...centroid angle of 141°

Graphical image persistence and code generation for object oriented databases

Attached is the detailed description of the design and implementation of graphical image persistence and code generation for object oriented databases. Graphical image persistent is incorporated into a graphics editor called OODINI. OODINI creates and manipulates graphical schemas for object-oriented databases. This graphical image on secondary storage is then translated into an abstract, generic code for dual model databases. This abstract code, DAL can then be converted into different dual model database languages. We provide an example by generating code for the VODAK Data Modeling language. It is also possible to generate a different abstract language code, OODAL from a graphical schema. This language does not have any dual model database architectural dependencies

Enhancement of post harvest fruit quality and leaf curl disease tolerance in tomato through hybrid breeding

Development of hybrids tolerant to leaf curl virus disease along with good post harvest/processing traits is the major thrust areas in tomato breeding now-a-days. A study was undertaken following 7 × 7 half diallel mating design utilizing four exotic and three indigenous lines to identify potential donors and crosses, to study the extent of heterobeltiosis and dominance behaviour, and to assess the genetic control of post harvest quality traits along with disease tolerance in tomato. Breeding strategies to improve characters governed by different types of gene action are discussed. Two parental lines, CLN 2777F and CLN 2777E could be utilized further in tomato breeding programme as they were identified as the most promising general combiners for fruit yield, processing quality and ToLCV tolerance. The maximum extent of heterobeltiosis (104.17%) was found in pericarp thickness followed by fruit yield plant-1 (63.57 %) and PDI of ToLCV disease (-60.00 %). The hybrids also exhibited various degrees of dominance effects. The study could also able to identify a promising cross ‘CLN 2777E × CLN 2777F’ which could be recommended for commercial exploitation after critical study in leaf curl disease prone areas of the tropics and sub-tropics

Optimal methylation noise for best chemotactic performance of {\sl E. coli}

In response to a concentration gradient of nutrient, E. coli bacterium modulates the rotational bias of flagellar motors which control its run-and-tumble motion, to migrate towards regions of high nutrient concentration. Presence of stochastic noise in the biochemical pathway of the cell has important consequence on the switching mechanism of motor bias, which in turn affects the runs and tumbles of the cell. We model the intra-cellular reaction network in terms of coupled time-evolution of three stochastic variables, kinase activity, methylation level and CheY-P protein level, and study the effect of methylation noise on the chemotactic performance of the cell. In presence of a spatially varying nutrient concentration profile, a good chemotactic performance allows the cell to climb up the concentration gradient fast and localize in the nutrient-rich regions in the long time limit. Our simulations show that the best performance is obtained at an optimal noise strength. While it is expected that chemotaxis will be weaker for very large noise, it is counter-intuitive that the performance worsens even when noise level falls below a certain value. We explain this striking result by detailed analysis of CheY-P protein level statistics for different noise strengths. We show that when the CheY-P level falls below a certain (noise-dependent) threshold, the cell tends to move down the concentration gradient of the nutrient, which has a detrimental effect on its chemotactic response. This threshold value decreases as noise is increased, and this effect is responsible for noise-induced enhancement of chemotactic performance. In a harsh chemical environment, when the nutrient degrades with time, the amount of nutrient intercepted by the cell trajectory, is an effective performance criterion. In this case also, we find an optimum noise strength, depending on the nutrient lifetime

Q-Pandora Unboxed: Characterizing Noise Resilience of Quantum Error Correction Codes

Quantum error correction codes (QECCs) are critical for realizing reliable quantum computing by protecting fragile quantum states against noise and errors. However, limited research has analyzed the noise resilience of QECCs to help select optimal codes. This paper conducts a comprehensive study analyzing two QECCs - rotated and unrotated surface codes - under different error types and noise models using simulations. Among them, rotated surface codes perform best with higher thresholds attributed to simplicity and lower qubit overhead. The noise threshold, or the point at which QECCs become ineffective, surpasses the error rate found in contemporary quantum processors. When confronting quantum hardware where a specific error or noise model is dominant, a discernible hierarchy emerges for surface code implementation in terms of resource demand. This ordering is consistently observed across unrotated, and rotated surface codes. Our noise model analysis ranks the code-capacity model as the most pessimistic and circuit-level model as the most realistic. The study maps error thresholds, revealing surface code's advantage over modern quantum processors. It also shows higher code distances and rounds consistently improve performance. However, excessive distances needlessly increase qubit overhead. By matching target logical error rates and feasible number of qubits to optimal surface code parameters, our study demonstrates the necessity of tailoring these codes to balance reliability and qubit resources. Conclusively, we underscore the significance of addressing the notable challenges associated with surface code overheads and qubit improvements.Comment: 15 pages; 9 figures; 3 table

Investigating impact of bit-flip errors in control electronics on quantum computation

In this paper, we investigate the impact of bit flip errors in FPGA memories in control electronics on quantum computing systems. FPGA memories are integral in storing the amplitude and phase information pulse envelopes, which are essential for generating quantum gate pulses. However, these memories can incur faults due to physical and environmental stressors such as electromagnetic interference, power fluctuations, and temperature variations and adversarial fault injections, potentially leading to errors in quantum gate operations. To understand how these faults affect quantum computations, we conducted a series of experiments to introduce bit flips into the amplitude (both real and imaginary components) and phase values of quantum pulses using IBM's simulated quantum environments, FakeValencia, FakeManila, and FakeLima. Our findings reveal that bit flips in the exponent and initial mantissa bits of the real amplitude cause substantial deviations in quantum gate operations, with TVD increases as high as ~200%. Interestingly, the remaining bits exhibited natural tolerance to errors. We proposed a 3-bit repetition error correction code, which effectively reduced the TVD increases to below 40% without incurring any memory overhead. Due to reuse of less significant bits for error correction, the proposed approach introduces maximum of 5-7% extra TVD in nominal cases. However, this can be avoided by sacrificing memory area for implementing the repetition code.Comment: 9 pages, 9 figures, conferenc

Lattice Surgery for Dummies

Quantum error correction (QEC) plays a crucial role in correcting noise and paving the way for fault-tolerant quantum computing. This field has seen significant advancements, with new quantum error correction codes emerging regularly to address errors effectively. Among these, topological codes, particularly surface codes, stand out for their low error thresholds and feasibility for implementation in large-scale quantum computers. However, these codes are restricted to encoding a single qubit. Lattice surgery is crucial for enabling interactions among multiple encoded qubits or between the lattices of a surface code, ensuring that its sophisticated error-correcting features are maintained without significantly increasing the operational overhead. Lattice surgery is pivotal for scaling QECCs across more extensive quantum systems. Despite its critical importance, comprehending lattice surgery is challenging due to its inherent complexity, demanding a deep understanding of intricate quantum physics and mathematical concepts. This paper endeavors to demystify lattice surgery, making it accessible to those without a profound background in quantum physics or mathematics. This work explores surface codes, introduces the basics of lattice surgery, and demonstrates its application in building quantum gates and emulating multi-qubit circuits.Comment: 10 pages, 13 figures, 1 tabl

A New strategy for on-line Droop adjustment for Microgrid connected DGs

This paper proposes a simple and effective control technique for interconnection of DG resources to the power grid via interfacing converters based on Phase locked loop (PLL) and Droop control. The behaviour of a Microgrid (MG) system during the transition from islanded mode to grid-connected mode of operation has been studied. A dynamic phase shifted PLL technique is locally designed for generating phase reference of each inverter. The phase angle between filter capacitor voltage vector and d-axis is dynamically adjusted with the change in q-axis inverter current to generate the phase reference of each inverter. During fluctuations in load capacity, the grid-connected system must be able to supply balanced power from the utility grid side and micro-grid side. Therefore, droop control is implemented to maintain a balanced power sharing. The inverter operates in voltage control mode in order to control the filter capacitor voltage. An adjusted droop control method for equivalent load sharing of parallel connected Inverters, without any communication between individual inverters, has been presented. The control loops are tested with aid of MATLAB Simulink tool during several operating conditions