726 research outputs found

    Resource-Efficient Quantum Circuits for Molecular Simulations: A Case Study of Umbrella Inversion in Ammonia

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    We conducted a thorough evaluation of various state-of-the-art strategies to prepare the ground state wavefunction of a system on a quantum computer, specifically within the framework of variational quantum eigensolver (VQE). Despite the advantages of VQE and its variants, the current quantum computational chemistry calculations often provide inaccurate results for larger molecules, mainly due to the polynomial growth in the depth of quantum circuits and the number of two-qubit gates, such as CNOT gates. To alleviate this problem, we aim to design efficient quantum circuits that would outperform the existing ones on the current noisy quantum devices. In this study, we designed a novel quantum circuit that reduces the required circuit depth and number of two-qubit entangling gates by about 60%, while retaining the accuracy of the ground state energies close to the chemical accuracy. Moreover, even in the presence of device noise, these novel shallower circuits yielded substantially low error rates than the existing approaches for predicting the ground state energies of molecules. By considering the umbrella inversion process in ammonia molecule as an example, we demonstrated the advantages of this new approach and estimated the energy barrier for the inversion process.Comment: 7 pages, 8 figure

    Deconvolution of dynamic mechanical networks

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    Time-resolved single-molecule biophysical experiments yield data that contain a wealth of dynamic information, in addition to the equilibrium distributions derived from histograms of the time series. In typical force spectroscopic setups the molecule is connected via linkers to a read-out device, forming a mechanically coupled dynamic network. Deconvolution of equilibrium distributions, filtering out the influence of the linkers, is a straightforward and common practice. We have developed an analogous dynamic deconvolution theory for the more challenging task of extracting kinetic properties of individual components in networks of arbitrary complexity and topology. Our method determines the intrinsic linear response functions of a given molecule in the network, describing the power spectrum of conformational fluctuations. The practicality of our approach is demonstrated for the particular case of a protein linked via DNA handles to two optically trapped beads at constant stretching force, which we mimic through Brownian dynamics simulations. Each well in the protein free energy landscape (corresponding to folded, unfolded, or possibly intermediate states) will have its own characteristic equilibrium fluctuations. The associated linear response function is rich in physical content, since it depends both on the shape of the well and its diffusivity---a measure of the internal friction arising from such processes like the transient breaking and reformation of bonds in the protein structure. Starting from the autocorrelation functions of the equilibrium bead fluctuations measured in this force clamp setup, we show how an experimentalist can accurately extract the state-dependent protein diffusivity using a straightforward two-step procedure.Comment: 9 pages, 3 figures + supplementary material 14 pages, 4 figure

    APOE-ε4 synergizes with sleep disruption to accelerate Aβ deposition and Aβ-associated tau seeding and spreading

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    Alzheimer\u27s disease (AD) is the most common cause of dementia. The APOE-ε4 allele of the apolipoprotein E (APOE) gene is the strongest genetic risk factor for late-onset AD. The APOE genotype modulates the effect of sleep disruption on AD risk, suggesting a possible link between apoE and sleep in AD pathogenesis, which is relatively unexplored. We hypothesized that apoE modifies Aβ deposition and Aβ plaque-associated tau seeding and spreading in the form of neuritic plaque-tau (NP-tau) pathology in response to chronic sleep deprivation (SD) in an apoE isoform-dependent fashion. To test this hypothesis, we used APPPS1 mice expressing human APOE-ε3 or -ε4 with or without AD-tau injection. We found that SD in APPPS1 mice significantly increased Aβ deposition and peri-plaque NP-tau pathology in the presence of APOE4 but not APOE3. SD in APPPS1 mice significantly decreased microglial clustering around plaques and aquaporin-4 (AQP4) polarization around blood vessels in the presence of APOE4 but not APOE3. We also found that sleep-deprived APPPS1:E4 mice injected with AD-tau had significantly altered sleep behaviors compared with APPPS1:E3 mice. These findings suggest that the APOE-ε4 genotype is a critical modifier in the development of AD pathology in response to SD

    Nitrogen Fixation By Groundnut (Arachis Hypogaea) In Intercropped And Rotational Systems

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    This paper examines the nodulation and nitrogen furation of groundnut when grown in pure culture or in associatbn with pearl millet, maize or sorghum. In all cases, association of groundnut with a cereal resulted in reduced nodulation and nitrogen fixation. This was ascribed to shading of the groundnut, leading to reduced photosynthesis. When grain milkt was planted in rotation wish groundnut or maize supplied 21) kg N/ha, yield following .groundnut were 524 kg/ha greater than obtained in the millet] maize rotation

    Nitrogen Fixation By Groundnut (Arachis Hypoga Ea) In Intercropped And Rotational Systems

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    This paper examines the nodulation and nitrogen furation of groundnut when grown in pure culture or in associatbn with pearl millet, maize or sorghum. In all cases, association of groundnut with a cereal resulted in reduced nodulation and nitrogen fixation. This was ascribed to shading of the groundnut, leading to reduced photosynthesis. When grain milkt was planted in rotation wish groundnut or maize supplied 21) kg N/ha, yield following .groundnut were 524 kg/ha greater than obtained in the millet] maize rotation

    A multi-centre cohort study evaluating the role of Inflammatory Markers In patient’s presenting with acute ureteric Colic (MIMIC)

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    BACKGROUND: Spontaneous Stone Passage (SSP) rates in acute ureteric colic range from 47–75%. There is conflicting evidence on the role of raised inflammatory markers in acute ureteric colic. The use of an easily applicable biomarker that could predict SSP or need for intervention would improve the management of obstructing ureteric stones. Thus, there is a need to determine in an appropriately powered study, in patients who are initially managed conservatively, which factors at the time of acute admission can predict subsequent patient outcome such as SSP and the need for intervention. Particularly, establishing whether levels of white cell count (WBC) at presentation are associated with likelihood of SSP or intervention may guide clinicians on the management of these patients’ stones. DESIGN: Multi-center cohort study disseminated via the UK British Urology Researchers in Surgical Training (BURST) and Australian Young Urology Researchers Organisation (YURO). PRIMARY RESEARCH QUESTION: What is the association between WBC and SSP in patients discharged from emergency department after initial conservative management? PATIENT POPULATION: Patients who have presented with acute renal colic with CT KUB evidence of a solitary ureteric stone. A minimum sample size of 720 patients across 15 centres will be needed. HYPOTHESIS: A raised WBC is associated with decreased odds of spontaneous stone passage. PRIMARY OUTCOME: The occurrence of SSP within six months of presentation with acute ureteric colic (YES/NO). SSP was defined as absence of need for intervention to assist stone passage STATISTICAL ANALYSIS PLAN: A multivariable logistic regression model will be constructed, where the outcome of interest is SSP using data from patients who do not undergo intervention at presentation. A random effect will be used to account for clustering of patients within hospitals/institutions. The model will include adjustments for gender, age as control variables

    Efficient coupler between silicon photonic and metal-insulator-silicon-metal plasmonic waveguides

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    We report the experimental realization of a compact, efficient coupler between silicon waveguides and vertical metal-insulator-silicon-metal (MISM) plasmonic waveguides. Devices were fabricated using complementary metal-oxide-silicon technology processes, with copper layers that support low-loss plasmonic modes in the MISM structures at a wavelength of 1550 nm. By implementing a short (0.5 μm) optimized metal-insulator-silicon-insulator structure inserted between the photonic and plasmonic waveguide sections, we demonstrate experimental coupling loss of 2.5 dB, despite the high optical confinement of the MISM mode and mismatch with the silicon waveguide mode

    Intercropping studies with annual crops

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    This paper tries to illustrate how beneficial interactions between crops can be exploited to increase the overall output of a cropping system. Growth studies with sorghum/pigeonpea and millet/groundnut are described to show how intercropping systems can achieve much larger yields than sole crops by using environmental resources more fully over time or more efficiently in space. Data from moisture stress studies are presented to illustrate that these advantages of intercropping can be even greater under stress conditions. Possible nitrogen benefits from legumes in intercropping systems are discussed with particular reference to a study on maize/groundnut. Weed, pest and disease control are considered and some effects of a sorghum intercrop on the incidence of pod borer and wilt disease in pigeonpea are described. Evidence for improved yield stability in intercropping systems is provided from a review of 94 experiments on sorghum/pigeonpea. It is emphasized that intercropping is especially beneficial to the small farmer in the low-input/high-risk environment of the developing areas of the world but some brief comments are made on its applicability in more developed conditions

    Effect of intercropping on nodulation and N2-fixation by groundnut

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    Nodulation and N2-fixation of groundnuts were studied in pure stands and intercropping systems. Intercropping with maize, sorghum or Pennisetum americanum reduced nodulation and N2-fixation. This is ascribed to shading of groundnuts by cereals and the consequent decrease in photosynthesis of the legume canopy

    Effects of quality improvement in health facilities and community mobilization through women's groups on maternal, neonatal and perinatal mortality in three districts of Malawi: MaiKhanda, a cluster randomized controlled effectiveness trial

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    BACKGROUND: Maternal, perinatal and neonatal mortality remains high in low-income countries. We evaluated community and facility-based interventions to reduce deaths in three districts of Malawi. METHODS: We evaluated a rural participatory women's group community intervention (CI) and a quality improvement intervention at health centres (FI) via a two-by-two factorial cluster randomized controlled trial. Consenting pregnant women were followed-up to 2 months after birth using key informants. Primary outcomes were maternal, perinatal and neonatal mortality. Clusters were health centre catchment areas assigned using stratified computer-generated randomization. Following exclusions, including non-birthing facilities, 61 clusters were analysed: control (17 clusters, 4912 births), FI (15, 5335), CI (15, 5080) and FI + CI (14, 5249). This trial was registered as International Standard Randomised Controlled Trial [ISRCTN18073903]. Outcomes for 14 576 and 20 576 births were recorded during baseline (June 2007–September 2008) and intervention (October 2008–December 2010) periods. RESULTS: For control, FI, CI and FI + CI clusters neonatal mortality rates were 34.0, 28.3, 29.9 and 27.0 neonatal deaths per 1000 live births and perinatal mortality rates were 56.2, 55.1, 48.0 and 48.4 per 1000 births, during the intervention period. Adjusting for clustering and stratification, the neonatal mortality rate was 22% lower in FI + CI than control clusters (OR = 0.78, 95% CI 0.60–1.01), and the perinatal mortality rate was 16% lower in CI clusters (OR = 0.84, 95% CI 0.72–0.97). We did not observe any intervention effects on maternal mortality. CONCLUSIONS: Despite implementation problems, a combined community and facility approach using participatory women's groups and quality improvement at health centres reduced newborn mortality in rural Malawi
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