The global technical potential of bio-energy in 2050 considering sustainability constraints

Bio-energy, that is, energy produced from organic non-fossil material of biological origin, is promoted as a substitute for non-renewable (e.g., fossil) energy to reduce greenhouse gas (GHG) emissions and dependency on energy imports. At present, global bio-energy use amounts to approximately 50 EJ/yr, about 10% of humanity's primary energy supply. We here review recent literature on the amount of bio-energy that could be supplied globally in 2050, given current expectations on technology, food demand and environmental targets ('technical potential'). Recent studies span a large range of global bio-energy potentials from ≈30 to over 1000 EJ/yr. In our opinion, the high end of the range is implausible because of (1) overestimation of the area available for bio-energy crops due to insufficient consideration of constraints (e.g., area for food, feed or nature conservation) and (2) too high yield expectations resulting from extrapolation of plot-based studies to large, less productive areas. According to this review, the global technical primary bio-energy potential in 2050 is in the range of 160-270 EJ/yr if sustainability criteria are considered. The potential of bio-energy crops is at the lower end of previously published ranges, while residues from food production and forestry could provide significant amounts of energy based on an integrated optimization ('cascade utilization') of biomass flows. © 2010 Elsevier B.V

Doubly heavy spin--1/2 baryon spectrum in QCD

We calculate the mass and residue of the heavy spin--1/2 baryons containing two heavy b or c quarks in the framework of QCD sum rules. We use the most general form of the interpolating current in its symmetric and anti-symmetric forms with respect to the exchange of heavy quarks, to calculate the two-point correlation functions describing the baryons under consideration. A comparison of the obtained results with existing predictions from various approaches is also made.Comment: 17 Pages, 2 Figures and 2 Table

Teaming Models with Intelligent Systems at the Workplace

Die Wirtschaftsinformatik (WI) hat sich einen festen Platz in den deutschsprachigen Hochschulen gesichert. Mit wachsendem Fachkräftemangel dürften ihre Beiträge zur Ausbildung von Fachleuten für automatische Systeme und zur diesbezüglichen Forschung noch wichtiger werden. In der Öffentlichkeit und z. T. auch in den Fachmedien entspricht ihr Bekanntheitsgrad nicht ihrer gesellschaftlichen Bedeutung. Beispielsweise werden von relativen Laien, z. B. in der Politik, traditionelle Gegenstände des Faches als Neuentwicklung dargestellt. Wir plädieren dafür, dass sich die WI mehr als bisher nicht nur als interdisziplinäres Fach zwischen BWL und Informatik begreift, sondern verstärkt auch auf Grenzgebieten wie Öffentlicher Verwaltung, Politik und Recht arbeitet. Wege dazu sind u. a. Übertragung von IT-Lösungen aus der Privatwirtschaft in die Öffentliche Verwaltung, Warnungen vor Übertreibung und Moden oder differenzierte Identifikation von Vor- und Nachteilen neuer Methoden im Vergleich zu bekannten. Im akademischen Umfeld ist zu hinterfragen, ob die aktuellen Anreizsysteme für Wissenschaftlerinnen und Wissenschaftler förderlich sind

Correlations of the elements of the neutrino mass matrix

Assuming Majorana nature of neutrinos, we re-investigate, in the light of the recent measurement of the reactor mixing angle, the allowed ranges for the absolute values of the elements of the neutrino mass matrix in the basis where the charged-lepton mass matrix is diagonal. Apart from the derivation of upper and lower bounds on the values of the matrix elements, we also study their correlations. Moreover, we analyse the sensitivity of bounds and correlations to the global fit results of the neutrino oscillation parameters which are available in the literature.Comment: 37 pages, 146 figures, minor corrections, 17 additional figures, version for publication in JHE

A Simple Grand Unified Relation between Neutrino Mixing and Quark Mixing

It is proposed that all flavor mixing is caused by the mixing of the three quark and lepton families with vectorlike fermions in 5 + 5-bar multiplets of SU(5). This simple assumption implies that both V_{CKM} and U_{MNS} are generated by a single matrix. The entire 3-by-3 complex mass matrix of the neutrinos M_{nu} is then found to have a simple expression in terms of two complex parameters and an overall scale. Thus, all the presently unknown neutrino parameters are predicted. The best fits are for theta_{atm} less than or approximately 40 degrees. The leptonic Dirac CP phase is found to be somewhat greater than pi radians.Comment: 10 pages, 4 figures, one table. Typos correcte

Land use change and the impact on greenhouse gas exchange in north Australian savanna soils

Savanna ecosystems are subjected to accelerating land use change as human demand for food and forest products increases. Land use change has been shown to both increase and decrease greenhouse gas fluxes from savannas and considerable uncertainty exists about the non-CO₂ fluxes from the soil. We measured methane (CH₄), nitrous oxide (N₂O) and carbon dioxide (CO₂) over a complete wet-dry seasonal cycle at three replicate sites of each of three land uses: savanna, young pasture and old pasture (converted from savanna 5–7 and 25–30 yr ago, respectively) in the Douglas Daly region of Northern Australia. The effect of break of season rains at the end of the dry season was investigated with two irrigation experiments. Land use change from savanna to pasture increased net greenhouse gas fluxes from the soil. Pasture sites were a weaker sink for CH₄ than savanna sites and, under wet conditions, old pastures turned from being sinks to a significant source of CH₄. Nitrous oxide emissions were generally very low, in the range of 0 to 5 μg N₂O-N m⁻² h⁻¹, and under dry conditions soil uptake of N₂O was apparent. Break of season rains produced a small, short lived pulse of N₂O up to 20 μg N₂O-N m⁻² h⁻¹, most evident in pasture soil. Annual cumulative soil CO₂ fluxes increased after clearing, with savanna (14.6 t CO₂-C ha⁻¹ yr⁻¹) having the lowest fluxes compared to old pasture (18.5 t CO₂-C ha⁻¹ yr⁻¹) and young pasture (20.0 t CO₂-C ha⁻¹ yr⁻¹). Clearing savanna increased soil-based greenhouse gas emissions from 53 to ∼ 70 t CO₂-equivalents, a 30% increase dominated by an increase in soil CO₂ emissions and shift from soil CH₄ sink to source. Seasonal variation was clearly driven by soil water content, supporting the emerging view that soil water content is a more important driver of soil gas fluxes than soil temperature in tropical ecosystems where temperature varies little among seasons

An Exploration of the Antecedents to Effective Recommender System Message Design

Recommender Systems (RS) aim to improve users’ decision quality and reduce decision-related effort. Prior research has focused on the impact of the entire system on recommendation acceptance and system use intentions, while largely overlooking the role of message design. To fill this void, a systematic literature review was undertaken to answer three research questions: (i) What comprises the current knowledge base of antecedents to effective RS message design? (ii) What significant results from past research can inform current scholars and practitioners of optimal RS message design practices? (iii) What are opportunities for future research in revealing guidelines for optimizing RS message design

Constrained analytical interrelations in neutrino mixing

Hermitian squared mass matrices of charged leptons and light neutrinos in the flavor basis are studied under general additive lowest order perturbations away from the tribimaximal (TBM) limit in which a weak basis with mass diagonal charged leptons is chosen. Simple analytical expressions are found for the three measurable TBM-deviants in terms of perturbation parameters appearing in the neutrino and charged lepton eigenstates in the flavor basis. Taking unnatural cancellations to be absent and charged lepton perturbation parameters to be small, interrelations are derived among masses, mixing angles and the amount of CP-violation.Comment: To be published in the Springer Proceedings in the Physics Series under the heading of the XXI DAE-BRNS Symposium (Guwahati, India