The characteristics of plutonic rocks in various climatic zones as shown on multiband satellite imagery

Imperial Users onl

Experimental implementation of a four-player quantum game

Game theory is central to the understanding of competitive interactions arising in many fields, from the social and physical sciences to economics. Recently, as the definition of information is generalized to include entangled quantum systems, quantum game theory has emerged as a framework for understanding the competitive flow of quantum information. Up till now only two-player quantum games have been demonstrated. Here we report the first experiment that implements a four-player quantum Minority game over tunable four-partite entangled states encoded in the polarization of single photons. Experimental application of appropriate quantum player strategies give equilibrium payoff values well above those achievable in the classical game. These results are in excellent quantitative agreement with our theoretical analysis of the symmetric Pareto optimal strategies. Our result demonstrate for the first time how non-trivial equilibria can arise in a competitive situation involving quantum agents and pave the way for a range of quantum transaction applications.Comment: 9 pages, 5 figure

Phage display-derived inhibitor of the essential cell wall biosynthesis enzyme MurF

Background To develop antibacterial agents having novel modes of action against bacterial cell wall biosynthesis, we targeted the essential MurF enzyme of the antibiotic resistant pathogen Pseudomonas aeruginosa. MurF catalyzes the formation of a peptide bond between D-Alanyl-D-Alanine (D-Ala-D-Ala) and the cell wall precursor uridine 5'-diphosphoryl N-acetylmuramoyl-L-alanyl-D-glutamyl-meso-diaminopimelic acid (UDP-MurNAc-Ala-Glu-meso-A2pm) with the concomitant hydrolysis of ATP to ADP and inorganic phosphate, yielding UDP-N-acetylmuramyl-pentapeptide. As MurF acts on a dipeptide, we exploited a phage display approach to identify peptide ligands having high binding affinities for the enzyme. Results Screening of a phage display 12-mer library using purified P. aeruginosa MurF yielded to the identification of the MurFp1 peptide. The MurF substrate UDP-MurNAc-Ala-Glumeso-A2pm was synthesized and used to develop a sensitive spectrophotometric assay to quantify MurF kinetics and inhibition. MurFp1 acted as a weak, time-dependent inhibitor of MurF activity but was a potent inhibitor when MurF was pre-incubated with UDP-MurNAc-Ala-Glu-meso-A2pm or ATP. In contrast, adding the substrate D-Ala-D-Ala during the pre-incubation nullified the inhibition. The IC50 value of MurFp1 was evaluated at 250 μM, and the Ki was established at 420 μM with respect to the mixed type of inhibition against D-Ala-D-Ala. Conclusion MurFp1 exerts its inhibitory action by interfering with the utilization of D-Ala-D-Ala by the MurF amide ligase enzyme. We propose that MurFp1 exploits UDP-MurNAc-Ala-Glu-meso-A2pm-induced structural changes for better interaction with the enzyme. We present the first peptide inhibitor of MurF, an enzyme that should be exploited as a target for antimicrobial drug development

Quantum singular-value decomposition of nonsparse low-rank matrices

We present a method to exponentiate nonsparse indefinite low-rank matrices on a quantum computer. Given access to the elements of the matrix, our method allows one to determine the singular values and their associated singular vectors in time exponentially faster in the dimension of the matrix than known classical algorithms. The method extends to non-Hermitian and nonsquare matrices via matrix embedding. Moreover, our method preserves the phase relations between the singular spaces allowing for efficient algorithms that require operating on the entire singular-value decomposition of a matrix. As an example of such an algorithm, we discuss the Procrustes problem of finding a closest isometry to a given matrix

Relationships Among Measures of Strength and Power and Health Outcomes in Youth

The interest in musculoskeletal fitness and its overall impact on health has been increasing in the last decade. The Institute of Medicine (2012) report called for the addition of several muscular fitness tests to national surveys of youth health-related physical fitness and to fitness test batteries in schools and other educational settings. Purpose: The purpose of this study was to examine the relationships among various muscular fitness tests and health outcomes in youth. Methods: Participants included 49 boys and girls aged 9 to 14 years. A series of muscular fitness tests and tests of health outcomes were completed in two test sessions. Muscular fitness tests included the standing long jump, vertical jump, upper body power throw, total body power throw, and handgrip strength. Handgrip strength was expressed in absolute terms and allometrically scaled to a power of 0.67. The health outcomes examined were aerobic capacity, body composition, systolic blood pressure (SBP), diastolic blood pressure (DBP), and physical activity. Aerobic capacity (VO₂[subscript]max) was directly measured during a maximal treadmill test. Body composition (percent fat) was assessed with the BODPOD. Blood pressure was measured via auscultation after 5 minutes of seated rest. Physical activity was quantified as minutes of moderate-to-vigorous physical activity (MVPA) from 7-day accelerometer measurement. Bivariate correlations were calculated to examine the relationships among fitness tests of strength and power and health outcomes. To control for the impact of body mass index (BMI) and age, partial correlations were calculated among fitness tests and health outcomes controlling for BMI z-score and age. To examine relationships among fitness tests and health outcomes from a criterion-referenced perspective, participants were categorized into both the aerobic capacity and body composition Healthy Fitness Zone (HFZ) and Needs Improvement Zone (NIZ) as defined by FitnessGram®. Effect size (ES) estimates were calculated with Cohen's delta to examine the size of the difference between the HFZ and NIZ groups on the fitness test variables. Results: SBP and VO₂[subscript]max were moderately correlated with several fitness tests, including total body power throw (r = .37, -.28), upper body power throw (r = .33, -.31), and dominant (r = .44, -.33) and nondominant handgrip strength (r = .37, -.34). Percent fat was moderately correlated with the standing long jump (r = -.45) and vertical jump (r = -.50). The correlation between percent fat and handgrip strength was close to zero when handgrip strength was expressed in absolute terms. Moderate correlations were found between percent fat and handgrip strength when handgrip strength was allometrically scaled for body mass (r = -.50 and -.48). When partial correlations controlling for BMI z-score and age were calculated, generally a similar pattern of correlations was found, except that the partial correlations among SBP and the throwing tests and absolute handgrip strength were lower than the bivariate correlations. When the HFZ was defined with aerobic capacity standards, the HFZ group did better on the standing long jump than the NIZ group (ES = 0.45). However, medium effect sizes demonstrated that the NIZ group did better than the HFZ group on total body power throw (ES = -0.42), upper body power throw (ES = -0.59), and absolute handgrip strength (ES = -0.48, -0.39). Differences in the vertical jump and allometrically scaled handgrip strength favored the HFZ group over the NIZ group, but these differences were generally small (range of ES = 0.16 to .32). When the HFZ was defined with body composition standards, effect size estimates revealed large differences between the HFZ and NIZ groups favoring the HFZ group for standing long jump (ES = 0.84), vertical jump (ES = 1.06), and allometrically scaled handgrip strength (ES = 1.30, 1.42). Small to medium effect sizes were found for total body power throw (ES = 0.26), upper body power throw (ES = 0.19), and absolute handgrip strength (ES = 0.36, 0.43) favoring the HFZ group over the NIZ group. Conclusion: Results demonstrated moderate levels of norm-referenced and criterion-referenced evidence that the tests of musculoskeletal fitness used in the current study are health-related. However, findings also indicated that the significant relationships between these musculoskeletal fitness tests and health outcomes are highly influenced by body composition.M.S

Citric acid cycle enzymes of Methylophilus methylotrophus

SIGLEAvailable from British Library Document Supply Centre- DSC:DX79219 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Contrasting Multicast Algorithms and XML with Afer

In recent years, much research has been devoted to the simulation of compilers; nevertheless, few have investigated the exploration of web browsers. Given the trends in distributed theory, futurists dubiously note the key unification of RPCs and spreadsheets, which embodies the technical principles of steganography. We confirm that although Web services and semaphores can collaborate to realize this ambition, suffix trees can be made distributed, wireless, and mobile

An efficient quantum algorithm for spectral estimation

We develop an efficient quantum implementation of an important signal processing algorithm for line spectral estimation: the matrix pencil method, which determines the frequencies and damping factors of signals consisting of finite sums of exponentially damped sinusoids. Our algorithm provides a quantum speedup in a natural regime where the sampling rate is much higher than the number of sinusoid components. Along the way, we develop techniques that are expected to be useful for other quantum algorithms as well—consecutive phase estimations to efficiently make products of asymmetric low rank matrices classically accessible and an alternative method to efficiently exponentiate non-Hermitian matrices. Our algorithm features an efficient quantum–classical division of labor: the time-critical steps are implemented in quantum superposition, while an interjacent step, requiring much fewer parameters, can operate classically. We show that frequencies and damping factors can be obtained in time logarithmic in the number of sampling points, exponentially faster than known classical algorithms

An analog quantum variational embedding classifier

Quantum machine learning has the potential to provide powerful algorithms for artificial intelligence. The pursuit of quantum advantage in quantum machine learning is an active area of research. For current noisy, intermediate-scale quantum (NISQ) computers, various quantum-classical hybrid algorithms have been proposed. One such previously proposed hybrid algorithm is a gate-based variational embedding classifier, which is composed of a classical neural network and a parameterized gate-based quantum circuit. We propose a quantum variational embedding classifier based on an analog quantum computer, where control signals vary continuously in time: our particular focus is implementation using quantum annealers. In our algorithm, the classical data is transformed into the parameters of the time-varying Hamiltonian of the analog quantum computer by a linear transformation. The nonlinearity needed for a nonlinear classification problem is purely provided by the analog quantum computer, through the nonlinear dependence of the final quantum state on the control parameters of the Hamiltonian. We performed numerical simulations that demonstrate the effectiveness of our algorithm for performing binary and multi-class classification on linearly inseparable datasets such as concentric circles and MNIST digits. Our algorithm performs much better than classical linear classifiers. We find that the performance of our classifier can be increased by increasing the number of qubits. Our algorithm presents the possibility to use current quantum annealers for solving practical machine-learning problems and it could also be useful to explore quantum advantage in quantum machine learning