4,220 research outputs found
Determination of the CKM Matrix Element |V_cb| from Semileptonic B Decays
We report studies of semileptonic decays, B --> X_c l nu, based on a sample
of 88 million BB events recorded with the BABAR detector. We have measured four
moments of the electron energy distribution and four moments of the hadronic
mass distribution, each as a function of the minimum electron energy. From
these moments we determine the inclusive branching fraction, the CKM matrix
element |V_cb|, and other heavy quark parameters, using Heavy Quark Expansions
(HQE) to order 1/m_b^3 in the kinetic mass scheme. In addition, we have studied
a large sample of exclusive B^0 --> D^*- l^+ nu decays. This sample is used to
extract the vector and axial form factors, the normalization and slope of the
HQET form factor to determine |V_cb|.Comment: 7 pages, 3 postscript figues, Talk presented at ICHEP04 in Beijin
Thermal-infrared spectral observations of geologic materials in emission
The thermal-infrared spectra of geologic materials in emission were studied using the prototype Thermal Emission Spectrometer (TES). A variety of of processes and surface modifications that may influence or alter the spectra of primary rock materials were studied. It was confirmed that thermal emission spectra contain the same absorption features as those observed in transmission and reflection spectra. It was confirmed that the TES instrument can be used to obtain relevant spectra for analysis of rock and mineral composition
Reflections and outlook for the New Zealand ETS: must uncertain times mean uncertain measures?
This article discusses the development and performance of New Zealand\u27s emissions trading scheme since the report of the Emissions Trading Scheme Review Panel in 2011.
Introduction
The New Zealand emissions trading scheme (ETS) was introduced by legislation in 2008. The legislated objectives as stated in section 3 of the Climate Change Response Act 2002 are to ‘support and encourage global efforts to reduce the emission of greenhouse gases by (i) assisting New Zealand to meet its international obligations under the [UNFCCC] Convention and the [Kyoto] Protocol; and (ii) reducing New Zealand’s net emissions of those gases to below business-as-usual levels’. Beyond this, the New Zealand government has confirmed three objectives for the ETS:
help New Zealand to deliver its ‘fair share’ of international action to reduce emissions, including meeting any international obligations;
deliver emission relations in the most cost-effective manner;
support efforts to maximise the long-term resilience of the New Zealand economy at least cost.
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This article discusses the development and performance of the scheme since the report of the Emissions Trading Scheme Review Panel in 2011. In particular, the article presents the results of a survey undertaken by the authors in April 2013 of stakeholders’ perception of the scheme and its performance. The survey was designed and administered by the authors using FluidSurveys software
Phase-coherent transport in InN nanowires of various sizes
We investigate phase-coherent transport in InN nanowires of various diameters
and lengths. The nanowires were grown by means of plasma-assisted molecular
beam epitaxy. Information on the phase-coherent transport is gained by
analyzing the characteristic fluctuation pattern in the magneto-conductance.
For a magnetic field oriented parallel to the wire axis we found that the
correlation field mainly depends on the wire cross section, while the
fluctuation amplitude is governed by the wire length. In contrast, if the
magnetic field is oriented perpendicularly, for wires longer than approximately
200 nm the correlation field is limited by the phase coherence length. Further
insight into the orientation dependence of the correlation field is gained by
measuring the conductance fluctuations at various tilt angles of the magnetic
field.Comment: 5 pages, 5 figure
An upper bound for the magnetic force gradient in graphite
Cervenka et al. have recently reported ferromagnetism along graphite steps.
We present Magnetic Force microscopy (MFM) data showing that the signal along
the steps is independent of an external magnetic field. Moreover, by combining
Kelvin Probe Force Microscopy (KPFM) and MFM, we are able to separate the
electrostatic and magnetic interactions along the steps obtaining an upper
bound for the magnetic force gradient of about16 microN/m, a figure six times
lower than the lowest theoretical bound reported by Cervenka et al. Our
experiments suggest absence of MFM signal in graphite at room temperature.Comment: 14 pages, including supplemetary informatio
Water solubility in aluminosilicate melts of haplogranite composition at 2 kbar
The compositional dependence of H2O solubility was investigated at 2 kbar and 800°C in haplogranite melts (system SiO2---1bNaAlSi3O8---1bKAlSi3O8 or Qz---1bAb---1bOr). The sixteen investigated compositions contained 25, 35 or 45 wt.% normative Qz and various Ab/(Ab+Or) ratios (0.15–0.92). Starting solid materials were anhydrous bubble-free glasses to which 10 wt.% H2O was added. The H2O contents of the isobarically quenched melts (glasses) were measured by Karl-Fischer titration.
The results show that H2O solubility in aluminosilicate melts depends significantly upon anhydrous composition. The highest solubility values are obtained for the most Ab-rich melts. At a constant normative quartz content, the solubility of water decreases from 6.49 ± 0.20 wt.% H2O for a composition Qz35Ab60Or05 (normative composition expressed in wt.%) to 5.50 ± 0.15 wt.% H2O for a composition Qz35Ab10Or55. Along this join, the most significant changes are observed for Ab-rich melts whereas H2O solubility in Or-rich melts remains almost constant.
The H2O solubility data imply that H2O is preferentially associated with the Ab component in aluminosilicate melts. Application of the results to natural granitic melts suggests that Na-rich, H2O-saturated melts may be significantly less viscous than H2O-saturated, K-rich melts.
The temperature dependence of H2O solubility, investigated for composition Qz28Ab38Or34 at 2 kbar, is low. Increasing temperature from 750° to 1150°C only causes a decrease in H2O solubility from 6.00 to 5.41 wt.% H2O. These data are in agreement with previous data obtained for albite melts
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