Leggett-Garg inequality in Markovian quantum dynamics: role of temporal sequencing of coupling to bath

We study Leggett-Garg inequalities (LGIs) for a two level system (TLS) undergoing Markovian dynamics described by unital maps. We find analytic expression of LG parameter $K_{3}$ (simplest variant of LGIs) in terms of the parameters of two distinct unital maps representing time evolution for intervals: $t_{1}$ to $t_{2}$ and $t_{2}$ to $t_{3}$. We show that the maximum violation of LGI for these maps can never exceed well known L\"{u}ders bound of $K_{3}^{L\ddot{u}ders}=3/2$ over the full parameter space. We further show that if the map for the time interval $t_{1}$ to $t_{2}$ is non-unitary unital then irrespective of the choice of the map for interval $t_{2}$ to $t_{3}$ we can never reach L\"{u}ders bound. On the other hand, if the measurement operator eigenstates remain pure upon evolution from $t_{1}$ to $t_{2}$, then depending on the degree of decoherence induced by the unital map for the interval $t_{2}$ to $t_{3}$ we may or may not obtain L\"{u}ders bound. Specifically, we find that if the unital map for interval $t_{2}$ to $t_{3}$ leads to the shrinking of the Bloch vector beyond half of its unit length, then achieving the bound $K_{3}^{L\ddot{u}ders}$ is not possible. Hence our findings not only establish a threshold for decoherence which will allow for $K_{3} = K_{3}^{L\ddot{u}ders}$, but also demonstrate the importance of temporal sequencing of the exposure of a TLS to Markovian baths in obtaining L\"{u}ders bound.Comment: 9 pages, 2 figure

Many-body interaction analysis: Algorithm development and application to large molecular clusters

A completely automated algorithm for performing many-body interaction energy analysis of clusters (MBAC) [M. J. Elrodt and R. J. Saykally, Chem. Rev. 94, 1975 (1994); S. S. Xantheas, J. Chem. Phys. 104, 8821 (1996)] at restricted Hartree-Fock (RHF)/MA Plesset 2nd order perturbation theory (MP2)/density functional theory (DFT) level of theory is reported. Use of superior guess density matrices (DM's) for smaller fragments generated from DM of the parent system and elimination of energetically insignificant higher-body combinations, leads to a more efficient performance (speed-up up to 2) compared to the conventional procedure. MBAC approach has been tested out on several large-sized weakly bound molecular clusters such as (H(2)O)(n), n=8, 12, 16, 20 and hydrated clusters of amides and aldehydes. The MBAC results indicate that the amides interact more strongly with water than aldehydes in these clusters. It also reconfirms minimization of the basis set superposition error for large cluster on using superior quality basis set. In case of larger weakly bound clusters, the contributions higher than four body are found to be repulsive in nature and smaller in magnitude. The reason for this may be attributed to the increased random orientations of the interacting molecules separated from each other by large distances.Financial support from the Council of Scientific and Industrial Research (CSIR), New Delhi, India and the Center for Development of Advanced Computing (C-DAC), Pune, India, is gratefully acknowledged

DSPatch: Dual Spatial Pattern Prefetcher

High main memory latency continues to limit performance of modern high-performance out-of-order cores. While DRAM latency has remained nearly the same over many generations, DRAM bandwidth has grown significantly due to higher frequencies, newer architectures (DDR4, LPDDR4, GDDR5) and 3D-stacked memory packaging (HBM). Current state-of-the-art prefetchers do not do well in extracting higher performance when higher DRAM bandwidth is available. Prefetchers need the ability to dynamically adapt to available bandwidth, boosting prefetch count and prefetch coverage when headroom exists and throttling down to achieve high accuracy when the bandwidth utilization is close to peak. To this end, we present the Dual Spatial Pattern Prefetcher (DSPatch) that can be used as a standalone prefetcher or as a lightweight adjunct spatial prefetcher to the state-of-the-art delta-based Signature Pattern Prefetcher (SPP). DSPatch builds on a novel and intuitive use of modulated spatial bit-patterns. The key idea is to: (1) represent program accesses on a physical page as a bit-pattern anchored to the first "trigger" access, (2) learn two spatial access bit-patterns: one biased towards coverage and another biased towards accuracy, and (3) select one bit-pattern at run-time based on the DRAM bandwidth utilization to generate prefetches. Across a diverse set of workloads, using only 3.6KB of storage, DSPatch improves performance over an aggressive baseline with a PC-based stride prefetcher at the L1 cache and the SPP prefetcher at the L2 cache by 6% (9% in memory-intensive workloads and up to 26%). Moreover, the performance of DSPatch+SPP scales with increasing DRAM bandwidth, growing from 6% over SPP to 10% when DRAM bandwidth is doubled.Comment: This work is to appear in MICRO 201

Structure-Activity Relationships of the Peptide Kappa Opioid Receptor Antagonist Zyklophin

The dynorphin (Dyn) A analog zyklophin ([N-benzyl-Tyr1-cyclo(D-Asp5,Dap8)]dynorphin A(1-11)NH2) is a kappa opioid receptor (KOR) selective antagonist in vitro, is active in vivo and antagonizes KOR in the CNS after systemic administration. Hence, we synthesized zyklophin analogs to explore the structure-activity relationships of this peptide. The synthesis of selected analogs required modification to introduce the N-terminal amino acid due to poor solubility and/or to avoid epimerization of this residue. Among the N-terminal modifications the N-phenethyl and the N-cyclopropylmethyl substitutions resulted in the analogs with the highest KOR affinities. Pharmacological results for the alanine-substituted analogs indicated that Phe4 and Arg6, but interestingly not the Tyr1, phenol are important for zyklophin’s KOR affinity, and Arg7 was important for KOR antagonist activity. In the GTPγS assay while all of the cyclic analogs exhibited negligible KOR efficacy, the N-phenethyl-Tyr1, N-CPM-Tyr1 and the N-benzyl-Phe1 analogs were 8- to 24-fold more potent KOR antagonists than zyklophin

Alanine scan of the opioid peptide dynorphin B amide

To date structure-activity relationship (SAR) studies of the dynorphins (Dyn), endogenous peptides for kappa opioid receptors (KOR), have focused almost exclusively on Dyn A with minimal studies on Dyn B. While both Dyn A and Dyn B have identical N-terminal sequences, their C-terminal sequences differ which could result in differences in pharmacological activity. We performed an alanine scan of the non-glycine residues up through residue 11 of Dyn B amide to explore the role of these side chains in the activity of Dyn B. The analogs were synthesized by fluorenylmethyloxycarbonyl (Fmoc)-based solid phase peptide synthesis and evaluated for their opioid receptor affinities and opioid potency and efficacy at KOR. Similar to Dyn A the N-terminal Tyr1 and Phe4 residues of Dyn B amide are critical for opioid receptor affinity and KOR agonist potency. The basic residues Arg6 and Arg7 contribute to the KOR affinity and agonist potency of Dyn B amide, while Lys10 contributes to the opioid receptor affinity, but not KOR agonist potency, of this peptide. Comparison to the Ala analogs of Dyn A(1-13) suggests that the basic residues in the C-terminus of both peptides contribute to KOR binding, but differences in their relative positions may contribute to the different pharmacological profiles of Dyn A and Dyn B. The other unique C-terminal residues in Dyn B amide also appear to influence the relative affinity of this peptide for KOR. This SAR information may be applied in the design of new Dyn B analogs that could be useful pharmacological tool

Functional outcome of anterior cruciate ligament reconstruction using bone-patellar tendon-bone graft: a descriptive observational study from Telangana

Background: The knee joint is the most commonly injured of all joints and the anterior cruciate ligament is the most commonly injured ligament. The bone-patellar tendon-bone (BPTB) autograft is the most commonly used autograft for reconstruction. The bone-patellar tendon-bone autograft has been widely accepted as the gold standard for ACL reconstruction with a high success rate. Objectives of the study were to study the functional outcome of ACL reconstruction using BPTB graft.Methods: The present descriptive observational study was carried out at department of orthopedics, Mediciti institute of medical sciences, Hyderabad involving 30 patients of ACL tear by simple random sampling method. Patients were then evaluated by both subjectively and objectively. They were evaluated by using Lysholm and Gilquist knee scoring scale. Data was analyzed by using SPSS 24.0 version IBM USA.Results: Majority of the patients i.e., 13 (43.3%) were from 26-35 years age group with right sided involvement in 60%. The result was found to be good in 16 i.e., 53.3%, excellent in 10 i.e., 33.3% and fair in 4 i.e., 13.3% patients. Prevalence of complications was reported as 23.3% in our study.Conclusions: Our study of ACL repair using BPTP gives good to excellent results within a span of one year