Deviations from Matthiessen's Rule for SrRuO3{\rm SrRuO_3} and CaRuO3{\rm CaRuO_3}

We have measured the change in the resistivity of thin films of ${\rm SrRuO_3}$ and ${\rm CaRuO_3}$ upon introducing point defects by electron irradiation at low temperatures, and we find significant deviations from Matthiessen's rule. For a fixed irradiation dose, the induced change in resistivity {\it decreases} with increasing temperature. Moreover, for a fixed temperature, the increase in resistivity with irradiation is found to be {\it sublinear}. We suggest that the observed behavior is due to the marked anisotropic scattering of the electrons together with their relatively short mean free path (both characteristic of many metallic oxides including cuprates) which amplify effects related to the Pippard ineffectiveness condition

Exact Kohn-Sham exchange kernel for insulators and its long-wavelength behavior

We present an exact expression for the frequency-dependent Kohn-Sham exact-exchange (EXX) kernel for periodic insulators, which can be employed for the calculation of electronic response properties within time-dependent (TD) density-functional theory. It is shown that the EXX kernel has a long-wavelength divergence behavior of the exact full exchange-correlation kernel and thus rectifies one serious shortcoming of the adiabatic local-density approximation and generalized-gradient approximations kernels. A comparison between the TDEXX and the GW-approximation-Bethe-Salpeter-equation approach is also made.Comment: two column format 6 pages + 1 figure, to be publisehd in Physical Review

Calculated optical properties of Si, Ge, and GaAs under hydrostatic pressure

The macroscopic dielectric function in the random-phase-approximation without local field effect has been implemented using the local density approximation with an all electron, full-potential linear muffin-tin orbital basis-set. This method is used to investigate the optical properties of the semiconductors Si, Ge, and GaAs under hydrostatic pressure. The pressure dependence of the effective dielectric function is compared to the experimental data of Go\~ni and coworkers, and an excellent agreement is found when the so called ``scissors-operator'' shift (SOS) is used to account for the correct band gap at $\Gamma$. The effect of the $3d$ semi-core states in the interband transitions hardly changes the static dielectric function, $\epsilon_\infty$; however, their contribution to the intensity of absorption for higher photon energies is substantial. The spin-orbit coupling has a significant effect on $\epsilon_\infty$ of Ge and GaAs, but not of Si. The $E_1$ peak in the dynamical dielectric function is strongly underestimated for Si, but only slightly for Ge and GaAs, suggesting that excitonic effects might be important only for Si.Comment: 29 RevTex pages and 12 figs; in press in Physical Review

Depolarization-Evoked Secretion Requires Two Vicinal Transmembrane Cysteines of Syntaxin 1A

BACKGROUND: The interactions of the voltage-gated Ca(2+) channel (VGCC) with syntaxin 1A (Sx 1A), Synaptosome-associated protein of 25 kD (SNAP-25), and synaptotagmin, couple electrical excitation to evoked secretion. Two vicinal Cys residues, Cys 271 and Cys 272 in the Sx 1A transmembrane domain, are highly conserved and participate in modulating channel kinetics. Each of the Sx1A Cys mutants, differently modify the kinetics of Cav1.2, and neuronal Cav2.2 calcium channel. METHODOLOGY/PRINCIPLE FINDINGS: We examined the effects of various Sx1A Cys mutants and the syntaxin isoforms 2, 3, and 4 each of which lack vicinal Cys residues, on evoked secretion, monitoring capacitance transients in a functional release assay. Membrane capacitance in Xenopus oocytes co-expressing Cav1.2, Sx1A, SNAP-25 and synaptotagmin, which is Bot C- and Bot A-sensitive, was elicited by a double 500 ms depolarizing pulse to 0 mV. The evoked-release was obliterated when a single Cys Sx1A mutant or either one of the Sx isoforms were substituted for Sx 1A, demonstrating the essential role of vicinal Cys residues in the depolarization mediated process. Protein expression and confocal imaging established the level of the mutated proteins in the cell and their targeting to the plasma membrane. CONCLUSIONS/SIGNIFICANCE: We propose a model whereby the two adjacent transmembranal Cys residues of Sx 1A, lash two calcium channels. Consistent with the necessity of a minimal fusion complex termed the excitosome, each Sx1A is in a complex with SNAP-25, Syt1, and the Ca(2+) channel. A Hill coefficient >2 imply that at least three excitosome complexes are required for generating a secreting hetero-oligomer protein complex. This working model suggests that a fusion pore that opens during membrane depolarization could be lined by alternating transmembrane segments of Sx1A and VGCC. The functional coupling of distinct amino acids of Sx 1A with VGCC appears to be essential for depolarization-evoked secretion

Chapter 7 - Energy systems

Stabilizing greenhouse gas (GHG) concentrations will require large-scale transformations in human societies, from the way that we produce and consume energy to how we use the land surface. A natural question in this context is what will be the .transformation pathway. towards stabilization; that is, how do we get from here to there? The topic of this chapter is transformation pathways. The chapter is primarily motivated by three questions. First, what are the near-term and future choices that define transformation pathways, including the goal itself, the emissions pathway to the goal, technologies used for and sectors contributing to mitigation, the nature of international coordination, and mitigation policies? Second, what are the key characteristics of different transformation pathways, including the rates of emissions reductions and deployment of low-carbon energy, the magnitude and timing of aggregate economic costs, and the implications for other policy objectives such as those generally associated with sustainable development? Third, how will actions taken today influence the options that might be available in the future? As part of the assessment in this chapter, data from over 1000 new scenarios published since the IPCC Fourth Assessment Report (AR4) were collected from integrated modelling research groups, many from large-scale model intercomparison studies. In comparison to AR4, new scenarios, both in this AR5 dataset and more broadly in the literature assessed in this chapter, consider more ambitious concentration goals, a wider range of assumptions about technology, and more possibilities for delays in additional global mitigation beyond that of today and fragmented international action

MetaCyto: A Tool for Automated Meta-analysis of Mass and Flow Cytometry Data

While meta-analysis has demonstrated increased statistical power and more robust estimations in studies, the application of this commonly accepted methodology to cytometry data has been challenging. Different cytometry studies often involve diverse sets of markers. Moreover, the detected values of the same marker are inconsistent between studies due to different experimental designs and cytometer configurations. As a result, the cell subsets identified by existing auto-gating methods cannot be directly compared across studies. We developed MetaCyto for automated meta-analysis of both flow and mass cytometry (CyTOF) data. By combining clustering methods with a silhouette scanning method, MetaCyto is able to identify commonly labeled cell subsets across studies, thus enabling meta-analysis. Applying MetaCyto across a set of ten heterogeneous cytometry studies totaling 2,926 samples enabled us to identify multiple cell populations exhibiting differences in abundance between demographic groups

Continuum spectroscopy with a (10)C beam: Cluster structure and three-body decay

Journals published by the American Physical Society can be found at http://publish.aps.org/Resonance-decay spectroscopy is used to study particle-unbound excited states produced in interactions of E/A=10.7 MeV (10)C on Be and C targets. After inelastic scattering, structures associated with excited states in (10)C were observed at 5.22, 5.29, 6.55, 6.56, 6.57, and 8.4 MeV which decay into the 2p+2 alpha final state. This final state is created via a number of different decay paths, which include prompt and sequential two-proton decay to the ground state of (8)Be, alpha decay to (6)Be(g.s.), and proton decay to the 2.345-MeV state of (9)B. For the sequential two-proton decay states (5.22 and 6.55 MeV), angular correlations between the first two decay axes indicate that the spin of these states are nonzero. For the prompt two-proton decay of the 5.29-MeV state, the three-body correlations between the two protons and the core are intermediate between those measured for ground-state (6)Be and (45)Fe decays. The 6.55- and 6.57-MeV structures are most probably associated with the same level, which has a 14% two-proton decay branch with a strong "diproton" character and a 86% sequential two-proton decay branch. Correlations between the fragments following the three-body decay of the 2.345-MeV state of (9)B can be approximately described by sequential alpha decay to the (5)Li intermediate state. The 8.06- and 9.61-MeV (10)B states that decay into the d+(6)Li(2.186) channel are confirmed. Evidence for cluster structure in (13)N is obtained from a number of excited states that decay into the p+3 alpha exit channel

Calcineurin Controls Voltage-Dependent-Inactivation (VDI) of the Normal and Timothy Cardiac Channels

Ca2+-entry in the heart is tightly controlled by Cav1.2 inactivation, which involves Ca2+-dependent inactivation (CDI) and voltage-dependent inactivation (VDI) components. Timothy syndrome, a subtype-form of congenital long-QT syndrome, results from a nearly complete elimination of VDI by the G406R mutation in the α11.2 subunit of Cav1.2. Here, we show that a single (A1929P) or a double mutation (H1926A-H1927A) within the CaN-binding site at the human C-terminal tail of α11.2, accelerate the inactivation rate and enhances VDI of both wt and Timothy channels. These results identify the CaN-binding site as the long-sought VDI-regulatory motif of the cardiac channel. The substantial increase in VDI and the accelerated inactivation caused by the selective inhibitors of CaN, cyclosporine A and FK-506, which act at the same CaN-binding site, further support this conclusion. A reversal of enhanced-sympathetic tone by VDI-enhancing CaN inhibitors could be beneficial for improving Timothy syndrome complications such as long-QT and autism

Positive biodiversity-productivity relationship predominant in global forests

The biodiversity-productivity relationship (BPR) is foundational to our understanding of the global extinction crisis and its impacts on ecosystem functioning. Understanding BPR is critical for the accurate valuation and effective conservation of biodiversity. Using ground-sourced data from 777,126 permanent plots, spanning 44 countries and most terrestrial biomes, we reveal a globally consistent positive concave-down BPR, showing that continued biodiversity loss would result in an accelerating decline in forest productivity worldwide. The value of biodiversity in maintaining commercial forest productivity alone - US$166 billion to 490 billion per year according to our estimation - is more than twice what it would cost to implement effective global conservation. This highlights the need for a worldwide reassessment of biodiversity values, forest management strategies, and conservation priorities.Peer Reviewe