Tensors Mesons in AdS/QCD

We explore tensor mesons in AdS/QCD focusing on f2 (1270), the lightest spin-two resonance in QCD. We find that the f2 mass and the partial width for f2 -> gamma gamma are in very good agreement with data. In fact, the dimensionless ratio of these two quantities comes out within the current experimental bound. The result for this ratio depends only on Nc and Nf, and the quark and glueball content of the operator responsible for the f2; more importantly, it does not depend on chiral symmetry breaking and so is both independent of much of the arbitrariness of AdS/QCD and completely out of reach of chiral perturbation theory. For comparison, we also explore f2 -> pi pi, which because of its sensitivity to the UV corrections has much more uncertainty. We also calculate the masses of the higher spin resonances on the Regge trajectory of the f2, and find they compare favorably with experiment.Comment: 21 pages, 1 figure; Li's correcte

New derivation for the equations of motion for particles in electromagnetism

We present equations of motion for charged particles using balanced equations, and without introducing explicitly divergent quantities. This derivation contains as particular cases some well known equations of motion, as the Lorentz-Dirac equations. An study of our main equations in terms of order of the interaction with the external field conduces us to the Landau-Lifshitz equations. We find that the analysis in second order show a special behavior. We give an explicit presentation up to third order of our main equations, and expressions for the calculation of general orders.Comment: 11 pages, 2 figures. Minor changes. Closer to published versio

Optimal Quantum Measurements of Expectation Values of Observables

Experimental characterizations of a quantum system involve the measurement of expectation values of observables for a preparable state |psi> of the quantum system. Such expectation values can be measured by repeatedly preparing |psi> and coupling the system to an apparatus. For this method, the precision of the measured value scales as 1/sqrt(N) for N repetitions of the experiment. For the problem of estimating the parameter phi in an evolution exp(-i phi H), it is possible to achieve precision 1/N (the quantum metrology limit) provided that sufficient information about H and its spectrum is available. We consider the more general problem of estimating expectations of operators A with minimal prior knowledge of A. We give explicit algorithms that approach precision 1/N given a bound on the eigenvalues of A or on their tail distribution. These algorithms are particularly useful for simulating quantum systems on quantum computers because they enable efficient measurement of observables and correlation functions. Our algorithms are based on a method for efficiently measuring the complex overlap of |psi> and U|psi>, where U is an implementable unitary operator. We explicitly consider the issue of confidence levels in measuring observables and overlaps and show that, as expected, confidence levels can be improved exponentially with linear overhead. We further show that the algorithms given here can typically be parallelized with minimal increase in resource usage.Comment: 22 page

The Forgotten Tribe in ODL Systems: Challenges Faced by Visually Impaired Students in Institutions of Higher Learning

This study sought to evaluate the challenges faced by visually impaired students in Open and Distance Learning (ODL) Institutions of Higher Learning. This was a case study of the Zimbabwe Open University. Twenty purposefully selected lecturers in the Faculty of Applied Social Sciences and ten blind and visually impaired students participated in the research. Data was collected through student interviews and questionnaires for lecturers and thematically analysed. The results indicated that whilst ODL offers flexible learning opportunities to all, there remains a forgotten tribe in the form of blind and visually impaired students. Consequently, visually impaired students face numerous challenges in their effort to become successful college students. These include lack of qualified lectures to teach them, equipment and services to adequately serve their needs. Both lecturers and visually impaired students felt there was need to have qualified professionals designated to the various needs of these students, appropriate resources for their learning environment should be provided, encourage faculty, academic advisors, staff and other students to proactively respond to the needs of students with visual impairment. The greater awareness that exists regarding visual impairment, the more likely it is that ODL institutions will meet the students’ needs. Further studies need to be done on facilitating the smooth inclusion of visually impaired students in ODL institutions of higher learning.Key words: visually impaired students, Braille, special needs students, academic advisors, IT systems, ODL institutions of higher learnin

Quantitative characterization of random partitioning in the evolution of plasmid-encoded traits

Plasmids are found across bacteria, archaea, and eukaryotes and play an important role in evolution. Plasmids exist at different copy numbers, the number of copies of the plasmid per cell, ranging from a single plasmid per cell to hundreds of plasmids per cell. This feature of a copy number greater than one can lead to a population of plasmids within a single cell that are not identical clones of one another, but rather have individual mutations that make a given plasmid unique. During cell division, this population of plasmids is partitioned into the two daughter cells, resulting in a random distribution of different plasmid variants in each daughter. In this study, we use stochastic simulations to investigate how random plasmid partitioning compares to a perfect partitioning model. Our simulation results demonstrate that random plasmid partitioning accelerates mutant allele fixation when the allele is beneficial and the selection is in an additive or recessive regime where increasing the copy number of the beneficial allele results in additional benefit for the host. This effect does not depend on the size of the benefit conferred or the mutation rate, but is magnified by increasing plasmid copy number

Restrictions on Transversal Encoded Quantum Gate Sets

Transversal gates play an important role in the theory of fault-tolerant quantum computation due to their simplicity and robustness to noise. By definition, transversal operators do not couple physical subsystems within the same code block. Consequently, such operators do not spread errors within code blocks and are, therefore, fault tolerant. Nonetheless, other methods of ensuring fault tolerance are required, as it is invariably the case that some encoded gates cannot be implemented transversally. This observation has led to a long-standing conjecture that transversal encoded gate sets cannot be universal. Here we show that the ability of a quantum code to detect an arbitrary error on any single physical subsystem is incompatible with the existence of a universal, transversal encoded gate set for the code.Comment: 4 pages, v2: minor change

The COVID-19 impact on crowdfunding performance: Evidence from a peer to-peer lending platform

The COVID-19 impact on global poverty dragged another 97 million people into poverty in 2020. Nonetheless, there is scant evidence reporting on the impacts on alternative means of financing designed to enable the poor during this global health crisis. This paper addresses this gap of funding impoverished entrepreneurs by studying the changes in their successfully funded campaigns on the largest crowdfunding microfinance platform prior and during COVID-19. After collecting data from January 2018 to November 2021 for a total of 767,112 campaigns, we report that the COVID-19 pandemic positively impacts on the funding success of the crowdfunding campaigns. However, rises in the daily number of COVID-19 cases negatively associate with campaigns getting fully funded. The odds of campaigns being fully funded decrease by 4.4% for a one thousand increase in new cases.info:eu-repo/semantics/publishedVersio

Three Dimensional Printing of Tungsten Carbide-Cobalt Using a Cobalt Oxide Precursor

Tungsten Carbide 10 wt% Cobalt parts were formed by Slurry-based Three Dimensional Printing (3DPTM). The slurry contained a mixture of Tungsten Carbide and Cobalt Oxide powders, as well as dispersing and redispersing agents. The cobalt oxide is fully reduced to cobalt metal during the early stages of the sintering process. A new binder system, polyethylenimine, is described for use with powders with acidic surfaces, such as WC. Sintered densities approach the theoretical values for WC-10% Co, and the microstructures produced are similar to those of conventionally processed (press and sinter) materials. Up to four parts were produced in a single print run using a layer thickness of 25 Pm, with good dimensional agreement between them, and within the range of target dimensions after sintering.Mechanical Engineerin

Scoping the potencial for outdoor microalgae production in the Azores

Microalgae cultivation has received much attention due to some desirable characteristics such as fast growth rates, high photosynthetic efficiencies and the production of valuable biochemicals. Mass cultivation of microalgae for commercial purposes is already a reality in some locations being an activity with approximately 45 years. The Azores archipelago, located in the North Atlantic Ocean off the coast of Portugal, features a temperate climate. To evaluate the feasibility of local outdoor microalgae production, certain fundamental factors must be analysed. In this study water, light, temperature, carbon sources, nutrients, international outlook and regional context were analyzed from the perspective of a local outdoor commercial microalgae production. A SWOT analysis was applied to the analysed factors to evaluate the strengths, weaknesses, opportunities and threats. The results nominate the Azores as a promising location to implement an outdoor production of valueadded products from microalgae.Oma – Observatório do Mar dos Açores ; MARE – Centro de Ciências do Mar e do Ambiente ; IMAR – Instituto do Mar ; DOP – Departamento de Oceanografia e Pescas ; Universidade dos Açoresinfo:eu-repo/semantics/publishedVersio

Linear Confinement and AdS/QCD

In a theory with linear confinement, such as QCD, the masses squared m^2 of mesons with high spin S or high radial excitation number n are expected, from semiclassical arguments, to grow linearly with S and n. We show that this behavior can be reproduced within a putative 5-dimensional theory holographically dual to QCD (AdS/QCD). With the assumption that such a dual theory exists and describes highly excited mesons as well, we show that asymptotically linear m^2 spectrum translates into a strong constraint on the INFRARED behavior of that theory. In the simplest model which obeys such a constraint we find m^2 ~ (n+S).Comment: 14 pages, 1 figur