20,177 research outputs found

    The role of spinning electrons in paramagnetic phenomena

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    An attempt is made to explain paramagnetic phenomena without assuming the orientation of a molecule or ion in a magnetic field. Only the spin angular momentum is assumed to be responsible. A derivative of the Gurie-Langevin law and the magnetic moments of ions are given as a function of the number of electrons in an inner, incomplete shell. An explanation of Gerlach's experiments with iron and nickel vapors is attempted. An explanation of magnetomechanical experiments with ferromagne elements is given

    Analysis of somatic mutations across the kinome reveals loss-of-function mutations in multiple cancer types

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    AbstractIn this study we use somatic cancer mutations to identify important functional residues within sets of related genes. We focus on protein kinases, a superfamily of phosphotransferases that share homologous sequences and structural motifs and have many connections to cancer. We develop several statistical tests for identifying Significantly Mutated Positions (SMPs), which are positions in an alignment with mutations that show signs of selection. We apply our methods to 21,917 mutations that map to the alignment of human kinases and identify 23 SMPs. SMPs occur throughout the alignment, with many in the important A-loop region, and others spread between the N and C lobes of the kinase domain. Since mutations are pooled across the superfamily, these positions may be important to many protein kinases. We select eleven mutations from these positions for functional validation. All eleven mutations cause a reduction or loss of function in the affected kinase. The tested mutations are from four genes, including two tumor suppressors (TGFBR1 and CHEK2) and two oncogenes (KDR and ERBB2). They also represent multiple cancer types, and include both recurrent and non-recurrent events. Many of these mutations warrant further investigation as potential cancer drivers.</jats:p

    Quasilocal energy for rotating charged black hole solutions in general relativity and string theory

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    We explore the (non)-universality of Martinez's conjecture, originally proposed for Kerr black holes, within and beyond general relativity. The conjecture states that the Brown-York quasilocal energy at the outer horizon of such a black hole reduces to twice its irreducible mass, or equivalently, to \sqrt{A} /(2\sqrt{pi}), where `A' is its area. We first consider the charged Kerr black hole. For such a spacetime, we calculate the quasilocal energy within a two-surface of constant Boyer-Lindquist radius embedded in a constant stationary-time slice. Keeping with Martinez's conjecture, at the outer horizon this energy equals the irreducible mass. The energy is positive and monotonically decreases to the ADM mass as the boundary-surface radius diverges. Next we perform an analogous calculation for the quasilocal energy for the Kerr-Sen spacetime, which corresponds to four-dimensional rotating charged black hole solutions in heterotic string theory. The behavior of this energy as a function of the boundary-surface radius is similar to the charged Kerr case. However, we show that in this case it does not approach the expression conjectured by Martinez at the horizon.Comment: 15 page

    Double burden of malnutrition among urban Bengalee adolescent boys in Midnapore, West Bengal, India

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    Malnutrition is an important public health problem worldwide. Therefore a study was undertaken to assess the prevalence of adolescent thinness, overweight and obesity in Midnapore town, West Bengal, India. A total of 974 adolescent boys aged 10-18 years were selected following multistage cluster sampling method from three higher secondary schools. Data was collected using pretested questionnaire following standard technique. Presence of thinness was evaluated using the cut-off values of international survey as suggested by Cole et al (2007). While overweight and obesity was determine by using international cut-off values develop by Cole et al (2000) based on international surveys as recommended by IOTF. Overall the prevalence of thinness, overweight and obesity were 20.8%, 14.9% and 3.8%, respectively. This study developed age specific smooth BMI percentile values using LMS method. Moreover, the study also developed BMI cut-off values to define thinness, overweight and obesity. In conclusion, the present analyses indicated that the prevalence of adolescent undernutrition is still a major problem. In addition, there was also an emerging trend for overweight/obesity, thereby indicating a double burden of malnutrition as observed in other developing countries

    Reproducing spin lattice models in strongly coupled atom-cavity systems

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    In an array of coupled cavities where the cavities are doped with an atomic V-system, and the two excited levels couple to cavity photons of different polarizations, we show how to construct various spin models employed in characterizing phenomena in condensed matter physics, such as the spin-1/2 Ising, XX, Heisenberg, and XXZ models. The ability to construct networks of arbitrary geometry also allows for the simulation of topological effects. By tuning the number of excitations present, the dimension of the spin to be simulated can be controlled, and mixtures of different spin types produced. The facility of single-site addressing, the use of only the natural hopping photon dynamics without external fields, and the recent experimental advances towards strong coupling, makes the prospect of using these arrays as efficient quantum simulators promising.Comment: 4 pages, 3 figures. v3: References adde

    Bayesian Approach for Counting Experiment Statistics applied to a Neutrino Point Source Analysis

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    In this paper we present a model independent analysis method following Bayesian statistics to analyse data from a generic counting experiment and apply it to the search for neutrinos from point sources. We discuss a test statistic defined following a Bayesian framework that will be used in the search for a signal. In case no signal is found, we derive an upper limit without the introduction of approximations. The Bayesian approach allows us to obtain the full probability density function for both the background and the signal rate. As such, we have direct access to any signal upper limit. The upper limit derivation directly compares with a frequentist approach and is robust in the case of low-counting observations. Furthermore, it allows also to account for previous upper limits obtained by other analyses via the concept of prior information without the need of the ad hoc application of trial factors. To investigate the validity of the presented Bayesian approach, we have applied this method to the public IceCube 40-string configuration data for 10 nearby blazars and we have obtained a flux upper limit, which is in agreement with the upper limits determined via a frequentist approach. Furthermore, the upper limit obtained compares well with the previously published result of IceCube, using the same data set.Comment: 15 pages, 7 figures, 1 tabl
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