Transversity and Collins functions from SIDIS and e+e- data

A global analysis of the experimental data on azimuthal asymmetries in semi-inclusive deep inelastic scattering (SIDIS), from the HERMES and COMPASS Collaborations, and in e+e- --> h1 h2 X processes, from the BELLE Collaboration, is performed. It results in the extraction of the Collins fragmentation function and, for the first time, of the transversity distribution function for u and d quarks. These turn out to have opposite signs and to be sizably smaller than their positivity bounds. Predictions for the azimuthal asymmetry A_{UT}^{sin(phi_h + phi_S)}, as will soon be measured at JLab and COMPASS operating on a transversely polarized proton target, are then presented.Comment: Revised version to appear in Phys. Rev. D. Few misprints corrected, new figure

The Sivers Function from SIDIS Data

We study the Sivers effect in transverse single spin asymmetries (SSA) for pion and kaon production in Semi-Inclusive Deep Inelastic Scattering (SIDIS) processes. We perform a fit of A^{sin(phi_h-phi_S)}_UT taking into account the recent data from HERMES and COMPASS Collaborations, which allow a new determination of the Sivers distribution functions for quark and anti-quark with u, d and also s flavours. Estimates for forthcoming SIDIS experiments at COMPASS and JLab are given.Comment: 4 pages, 1 figure. To appear in the proceedings of the XVI International Workshop on Deep-Inelastic Scattering and Related Subjects, DIS 2008, London, U.K., 7-11 April 200

Biogeochemical variations at the Porcupine Abyssal Plain sustained Observatory in the northeast Atlantic Ocean, from weekly to inter-annual timescales

We present high-resolution autonomous measurements of carbon dioxide partial pressure p(CO2) taken in situ at the Porcupine Abyssal Plain sustained Observatory (PAP-SO) in the northeast Atlantic (49° N, 16.5° W; water depth of 4850 m) for the period 2010–2012. Measurements of p(CO2) made at 30 m depth on a sensor frame are compared with other autonomous biogeochemical measurements at that depth (including chlorophyll a fluorescence and nitrate concentration data) to analyse weekly to seasonal controls on p(CO2) flux in the inter-gyre region of the North Atlantic. Comparisons are also made with in situ regional time series data from a ship of opportunity and mixed layer depth (MLD) measurements from profiling Argo floats. There is a persistent under-saturation of CO2 in surface waters throughout the year which gives rise to a perennial CO2 sink. Comparison with an earlier data set collected at the site (2003–2005) confirms seasonal and inter-annual changes in surface seawater chemistry. There is year-to-year variability in the timing of deep winter mixing and the intensity of the spring bloom.The 2010–2012 period shows an overall increase in p(CO2) values when compared to the 2003–2005 period as would be expected from increases due to anthropogenic CO2 emissions. The surface temperature, wind speed and MLD measurements are similar for both periods of time. Future work should incorporate daily CO2 flux measurements made using CO2 sensors at 1 m depth and the in situ wind speed data now available from the UK Met Office Buoy

Towards the model driven organization

Todays modern organization is faced with a need for rapid response to changes from external business pressures by updating systems and operational procedures. The effect of such continuous evolution eventually leads to sub- optimal configurations of its underlying systems. The management of continuous business change is compromised by uncertainty due to the inadequacy of existing mechanisms for responding to multiple change drivers thus leading to signifi- cant organizational costs. This represents a major opportunity for seeking greater efficiencies. To date, there has been little or no attempt to apply model driven principles or approaches to addressing these issues. We present a new vision of a Model Driven Organisation (MDO) that has the potential to increase produc- tivity by promoting integration of business processes and collaborations across the organisation whilst supporting safe and convenient adaptations that enable rapid response to change whilst maintaining integrity of the systems within the organisation. The approach proposed is based on the use of modelling languages and simulation technologies that support abstractions for understanding business goals through to specification of IT systems and ultimately to deployed systems. The paper motivates the problem and proposes a definition of the MDO. We val- idate the proposal through an illustrative case and conclude with a review of the state of the art leading to a roadmap of research and emergent grand challenges towards achieving the MDO vision

A Multi-Code Analysis Toolkit for Astrophysical Simulation Data

The analysis of complex multiphysics astrophysical simulations presents a unique and rapidly growing set of challenges: reproducibility, parallelization, and vast increases in data size and complexity chief among them. In order to meet these challenges, and in order to open up new avenues for collaboration between users of multiple simulation platforms, we present yt (available at http://yt.enzotools.org/), an open source, community-developed astrophysical analysis and visualization toolkit. Analysis and visualization with yt are oriented around physically relevant quantities rather than quantities native to astrophysical simulation codes. While originally designed for handling Enzo's structure adaptive mesh refinement (AMR) data, yt has been extended to work with several different simulation methods and simulation codes including Orion, RAMSES, and FLASH. We report on its methods for reading, handling, and visualizing data, including projections, multivariate volume rendering, multi-dimensional histograms, halo finding, light cone generation and topologically-connected isocontour identification. Furthermore, we discuss the underlying algorithms yt uses for processing and visualizing data, and its mechanisms for parallelization of analysis tasks.Comment: 18 pages, 6 figures, emulateapj format. Resubmitted to Astrophysical Journal Supplement Series with revisions from referee. yt can be found at http://yt.enzotools.org

The Economics of Residential Solar and Battery Storage: Analyzing the Impact of the Joint IOU Proposal for Net Metering 3.0 in California

The California Public Utilities Commission (CPUC) is currently deciding on the structure of the next net metering program, which will determine how customers who install solar panels (and battery storage) under this new program will be compensated for excess energy that they export to the grid, and the additional fees that these solar customers will have to pay. The major investor-owned utility (IOU) companies in the state and some legislators have argued that the current net metering programs are far too generous to the customers and that they create an inequity by favoring the wealthy and causing a cost shift to the poorer non-solar customers. The IOUs have jointly proposed a set of regulations to the CPUC. In this paper, we examine the financial implications to residential customers who go solar under the new net metering program if the joint IOU proposal were to be adopted. We examine the case of a hypothetical southern California home that consumes the average amount of electricity (for that region) and estimate its electricity bills for various load profiles, assuming no solar or battery storage, with solar alone, and with solar and battery storage. For the two latter scenarios, we determine the ideal system configuration that will maximize the customer’s financial returns. In all cases, we determine that the joint IOU proposal for net metering will make residential solar panel and battery storage installations financially unattractive even in the best-case scenarios. In short, if the CPUC adopts the joint IOU proposal then residential solar installations in the state would likely come to an abrupt stop. We also analyze the economics of going off-grid (where a customer completely cuts himself off from the electrical grid) and find that it does not make sense for customers to go off-grid without being willing to cut consumption or make other compromises

Second order analysis of geometric functionals of Boolean models

This paper presents asymptotic covariance formulae and central limit theorems for geometric functionals, including volume, surface area, and all Minkowski functionals and translation invariant Minkowski tensors as prominent examples, of stationary Boolean models. Special focus is put on the anisotropic case. In the (anisotropic) example of aligned rectangles, we provide explicit analytic formulae and compare them with simulation results. We discuss which information about the grain distribution second moments add to the mean values.Comment: Chapter of the forthcoming book "Tensor Valuations and their Applications in Stochastic Geometry and Imaging" in Lecture Notes in Mathematics edited by Markus Kiderlen and Eva B. Vedel Jensen. (The second version mainly resolves minor LaTeX problems.

Sivers Effect for Pion and Kaon Production in Semi-Inclusive Deep Inelastic Scattering

We study the Sivers effect in the transverse single spin asymmetries (SSA) for pion and kaon production in semi-inclusive deep inelastic scattering (SIDIS) processes. We perform a fit of A^sin(phi_h-phi_S)_UT which, by including recent high statistics experimental data for pion and kaon production from HERMES and COMPASS Collaborations, allows a new determination of the Sivers distribution functions for quarks and antiquarks with u, d and s flavours. Estimates for forthcoming SIDIS experiments at COMPASS and JLab are given.Comment: 16 pages, 19 figures; v2: no changes in results and conclusions; some sentences rephrased, few paragraphs (and references) added; a new table (table 2) with individual chi^2 per data points added; figures for JLab at 6 GeV removed; matches the version published on Eur. Phys. J.

Effects of Varying the Three-Body Molecular Hydrogen Formation Rate in Primordial Star Formation

The transformation of atomic hydrogen to molecular hydrogen through three-body reactions is a crucial stage in the collapse of primordial, metal-free halos, where the first generation of stars (Population III stars) in the Universe are formed. However, in the published literature, the rate coefficient for this reaction is uncertain by nearly an order of magnitude. We report on the results of both adaptive mesh refinement (AMR) and smoothed particle hydrodynamics (SPH) simulations of the collapse of metal-free halos as a function of the value of this rate coefficient. For each simulation method, we have simulated a single halo three times, using three different values of the rate coefficient. We find that while variation between halo realizations may be greater than that caused by the three-body rate coefficient being used, both the accretion physics onto Population III protostars as well as the long-term stability of the disk and any potential fragmentation may depend strongly on this rate coefficient.Comment: 29 pages, 7 figures; Accepted for publication in The Astrophysical Journa

Attenuation of lead toxicity by promotion of tolerance mechanism in wheat roots by lipoic acid

This study was performed to determine the possible ameliorative effect of alpha-lipoic acid (LA) against oxidative stress evoked by lead (Pb) toxicity on 5-d wheat seedlings and elucidate how this ameliorative process was mediated. Pb toxicity caused a significant reduction in early seedling growth as evidenced by stunted root and coleoptile growth. To cope with the Pb toxicity, the activities of antioxidant enzymes were significantly stimulated compared to the control. However, in spite of high activities of these enzymes, contents of reactive oxygen species (ROS), superoxide anion and hydrogen peroxide and lipid peroxidation level were significantly high compared with the control. Similarly, Pb toxicity caused a marked decrease in the level of reduced forms of ascorbate and glutathione and thus it changed their reduced/oxidized ratio in favor of oxidized forms. On the other hand, LA supplementation further promoted uptake, accumulation, and transportation of Pb by stimulating tolerance mechanism involving ion uptake/accumulation at a high level. Moreover, ROS content and lipid peroxidation level were recorded as lower than that of the stressed-ones alone. In addition, while Pb toxicity markedly reduced amylase activity by decreasing Ca2+ content in endosperms, LA supplementation mitigated the reduction in amylase activity by increasing Ca2+ content. The changes in amylase activity were supported by isozymes patterns. Taken together, LA carried out its ameliorative effect against Pb toxicity via stimulation of tolerance mechanism, and this mechanism was linked to regeneration of the other main antioxidant compounds due to its own antioxidant property instead of activation of antioxidant enzymes