120 research outputs found
Partial Oxidation of Propylene over as Prepared and Acid Enriched Bi2Mo1-xWxO6 System
The compounds Bi2Mo1-xWxO6Â (x = 0.0, 0.2, and 0.4) were obtained through a Citrate sol-gel process. Thermogravimetric differential thermal analysis (TG-DTA), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) techniques were used for characterization. Reitveld refinement of the XRD data confirmed the crystal structure of all the compositions to be orthorhombic, having Pca21 space group. XPS studies indicated the presence of +6 as well as +4 oxidation state for Mo. Surface acid enrichment of all the catalysts was done and monitored by NH3-TPD studies. Partial oxidation of propylene was studied over all the compounds. The W doping was found to increase the catalytic activity. Moreover, as-prepared catalysts and acid enriched catalysts were compared for their catalytic activity wherein, acid-enriched catalysts showed the improved conversion of propylene without hampering the product selectivity profile.
AUTOMATIC TUNING THE EXPIRY TIME BASED ON ACCURACY AT LBS
Location-based services (LBS) empower portable clients to question purposes of-interest (e.g., eateries, bistros) on different elements (e.g., value, quality, and assortment). What's more, clients require exact inquiry results with a la mode travel times. Without the observing foundation for street activity, the LBS may get live travel times of courses from online course APIs keeping in mind the end goal to offer exact results. Our objective is to decrease the quantity of solicitations issued by the LBS essentially while saving precise inquiry results. To start with, we propose to misuse late courses asked for from course APIs to answer inquiries precisely. At that point, we outline viable lower/upper bounding methods and requesting strategies to process questions effectively. Additionally, we consider parallel course demands to facilitate lessen the question reaction time. Our exploratory assessment demonstrates that our answer is three times more effective than a contender, but then accomplishes high result accuracy (above 98 percent).
Analyzing the genetic relatedness of pigeonpea varieties released over last 58 years in India
The genetic base of 150 pigeonpea varieties released in India during1960 to 2018 was examined. Of these, 89, 57, three, and one variety were developed by pedigree selection, pureline selection, mutation and population improvement, respectively. Examination of pedigree records of 89 pigeonpea varieties developed through pedigree breeding method between 1971 and 2018 traced back to 113 ancestors. The highest mean genetic contribution was recorded for the genotype T 190 (0.051) accompanied by UPAS 120 (0.049) and ICP 8863 (0.043). The ancestor T 190 appeared with highest frequency of 21, directly as one of the parent (male/female) in four varieties and indirectly in the development of 17 varieties. Similarly, the ancestors UPAS 120 and ICP 8863 were more frequently used (in nine varieties) as direct parents followed by T 21 and C 11 (in five varieties). The variety PRG 176 involved the highest number (9) of ancestors during the course of its development followed by the variety VBN (Rg) 3 with eight ancestors. Results indicated that 51.69% (46 of the 89 varieties) of released varieties were developed through bi-parental crossing whereas 48.31% involved multiple parents. The frequent use of a limited number of ancestors has caused the narrow genetic base of released pigeonpea varieties. We recommend large-scale deployment of novel germplasm resources for generating broad-base breeding populations. This will help to obtain improved pigeonpea cultivars with high grain yield, biotic tolerance and climate adaptation
A New Strategy of Quantum-State Estimation for Achieving the Cramer-Rao Bound
We experimentally analyzed the statistical errors in quantum-state estimation
and examined whether their lower bound, which is derived from the Cramer-Rao
inequality, can be truly attained or not. In the experiments, polarization
states of bi-photons produced via spontaneous parametric down-conversion were
estimated employing tomographic measurements. Using a new estimation strategy
based on Akaike's information criterion, we demonstrated that the errors
actually approach the lower bound, while they fail to approach it using the
conventional estimation strategy.Comment: 4 pages, 2 figure
Interferometric Bell-state preparation using femtosecond-pulse-pumped Spontaneous Parametric Down-Conversion
We present theoretical and experimental study of preparing maximally
entangled two-photon polarization states, or Bell states, using femtosecond
pulse pumped spontaneous parametric down-conversion (SPDC). First, we show how
the inherent distinguishability in femtosecond pulse pumped type-II SPDC can be
removed by using an interferometric technique without spectral and amplitude
post-selection. We then analyze the recently introduced Bell state preparation
scheme using type-I SPDC. Theoretically, both methods offer the same results,
however, type-I SPDC provides experimentally superior methods of preparing Bell
states in femtosecond pulse pumped SPDC. Such a pulsed source of highly
entangled photon pairs is useful in quantum communications, quantum
cryptography, quantum teleportation, etc.Comment: 11 pages, two-column format, to appear in PR
Wave functions and decay constants of and mesons in the relativistic potential model
With the decay constants of and mesons measured in experiment
recently, we revisit the study of the bound states of quark and antiquark in
and mesons in the relativistic potential model. The relativistic bound
state wave equation is solved numerically. The masses, decay constants and wave
functions of and mesons are obtained. Both the masses and decay
constants obtained here can be consistent with the experimental data. The wave
functions can be used in the study of and meson decays.Comment: more discussion added, to appear in EPJ
Heavy quarkonium: progress, puzzles, and opportunities
A golden age for heavy quarkonium physics dawned a decade ago, initiated by
the confluence of exciting advances in quantum chromodynamics (QCD) and an
explosion of related experimental activity. The early years of this period were
chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in
2004, which presented a comprehensive review of the status of the field at that
time and provided specific recommendations for further progress. However, the
broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles
could only be partially anticipated. Since the release of the YR, the BESII
program concluded only to give birth to BESIII; the -factories and CLEO-c
flourished; quarkonium production and polarization measurements at HERA and the
Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the
deconfinement regime. All these experiments leave legacies of quality,
precision, and unsolved mysteries for quarkonium physics, and therefore beg for
continuing investigations. The plethora of newly-found quarkonium-like states
unleashed a flood of theoretical investigations into new forms of matter such
as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the
spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b},
and b\bar{c} bound states have been shown to validate some theoretical
approaches to QCD and highlight lack of quantitative success for others. The
intriguing details of quarkonium suppression in heavy-ion collisions that have
emerged from RHIC have elevated the importance of separating hot- and
cold-nuclear-matter effects in quark-gluon plasma studies. This review
systematically addresses all these matters and concludes by prioritizing
directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K.
Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D.
Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A.
Petrov, P. Robbe, A. Vair
The Emissions Model Intercomparison Project (Emissions-MIP): quantifying model sensitivity to emission characteristics
Anthropogenic emissions of aerosols and precursor compounds are known to significantly affect the energy balance of the Earthâatmosphere system, alter the formation of clouds and precipitation, and have a substantial impact on human health and the environment. Global models are an essential tool for examining the impacts of these emissions. In this study, we examine the sensitivity of model results to the assumed height of SO2 injection, seasonality of SO2 and black carbon (BC) particulate emissions, and the assumed fraction of SO2 emissions that is injected into the atmosphere as particulate phase sulfate (SO4) in 11 climate and chemistry models, including both chemical transport models and the atmospheric component of Earth system models. We find large variation in atmospheric lifetime across models for SO2, SO4, and BC, with a particularly large relative variation for SO2, which indicates that fundamental aspects of atmospheric sulfur chemistry remain uncertain. Of the perturbations examined in this study, the assumed height of SO2 injection had the largest overall impacts, particularly on global mean net radiative flux (maximum difference of â0.35âWâmâ2), SO2 lifetime over Northern Hemisphere land (maximum difference of 0.8âd), surface SO2 concentration (up to 59â% decrease), and surface sulfate concentration (up to 23â% increase). Emitting SO2 at height consistently increased SO2 and SO4 column burdens and shortwave cooling, with varying magnitudes, but had inconsistent effects across models on the sign of the change in implied cloud forcing. The assumed SO4 emission fraction also had a significant impact on net radiative flux and surface sulfate concentration. Because these properties are not standardized across models this is a source of inter-model diversity typically neglected in model intercomparisons. These results imply a need to ensure that anthropogenic emission injection height and SO4 emission fraction are accurately and consistently represented in global models
Observational cohort study to determine the degree and causes of variation in the rate of surgery or primary endocrine therapy in older women with operable breast cancer
Background
In the UK there is variation in the treatment of older women with breast cancer, with up to 40% receiving primary endocrine therapy (PET), which is associated with inferior survival. Case mix and patient choice may explain some variation in practice but clinician preference may also be important.
Methods
A multicentre prospective cohort study of women aged >70 with operable breast cancer. Patient characteristics (health status, age, tumour characteristics, treatment allocation and decision-making preference) were analysed to identify whether treatment variation persisted following case-mix adjustment. Expected case-mix adjusted surgery rates were derived by logistic regression using the variables age, co-morbidity, tumour stage and grade. Concordance between patientsâ preferred and actual decision-making style was assessed and associations between age, treatment and decision-making style calculated.
Results
Women (median age 77, range 70â102) were recruited from 56 UK breast units between 2013 and 2018. Of 2854/3369 eligible women with oestrogen receptor positive breast cancer, 2354 were treated with surgery and 500 with PET. Unadjusted surgery rates varied between hospitals, with 23/56 units falling outside the 95% confidence intervals on funnel plots. Adjusting for case mix reduced, but did not eliminate, this variation between hospitals (10/56 units had practice outside the 95% confidence intervals). Patients treated with PET had more patient-centred decisions compared to surgical patients (42.2% vs 28.4%, pâŻ<âŻ0.001).
Conclusions
This study demonstrates variation in treatment selection thresholds for older women with breast cancer. Health stratified guidelines on thresholds for PET would help reduce variation, although patient preference should still be respected
Mechanical systems in the quantum regime
Mechanical systems are ideal candidates for studying quantumbehavior of
macroscopic objects. To this end, a mechanical resonator has to be cooled to
its ground state and its position has to be measured with great accuracy.
Currently, various routes to reach these goals are being explored. In this
review, we discuss different techniques for sensitive position detection and we
give an overview of the cooling techniques that are being employed. The latter
include sideband cooling and active feedback cooling. The basic concepts that
are important when measuring on mechanical systems with high accuracy and/or at
very low temperatures, such as thermal and quantum noise, linear response
theory, and backaction, are explained. From this, the quantum limit on linear
position detection is obtained and the sensitivities that have been achieved in
recent opto and nanoelectromechanical experiments are compared to this limit.
The mechanical resonators that are used in the experiments range from
meter-sized gravitational wave detectors to nanomechanical systems that can
only be read out using mesoscopic devices such as single-electron transistors
or superconducting quantum interference devices. A special class of
nanomechanical systems are bottom-up fabricated carbon-based devices, which
have very high frequencies and yet a large zero-point motion, making them ideal
for reaching the quantum regime. The mechanics of some of the different
mechanical systems at the nanoscale is studied. We conclude this review with an
outlook of how state-of-the-art mechanical resonators can be improved to study
quantum {\it mechanics}.Comment: To appear in Phys. Re
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