Molecular memories in the regulation of seasonal flowering: from competence to cessation

Plants commit to flowering based on endogenous and exogenous information that they can remember across mitotic cell divisions. Here, we review how signal perception and epigenetic memory converge at key integrator genes, and we show how variation in their regulatory circuits supports the diversity of plant lifestyles

Introduction To Special Issue Popular Culture In Asia

Popular culture is not new, but the formal academic study of popular culture is. It began about 50 years ago and the discipline has grown considerably during that time. Because East Asia has many diverse elements and cultures, all of which deserve serious examination, it is completely appropriate that there should be an academic organisation dedicated to its study. The first East Asian Popular Culture Association Conference∗ was held in Taipei from 1 to 4 September 2011. At that meeting, scholars from 18 nations delivered almost 100 papers including three presentations by prominent scholars who delivered keynote talks. The sessions were lively and thoughtful and included serious discussion of the issues that participants developed. But not all the time was devoted to formal sessions. Attendees enjoyed a walking tour of the ShiDa night market as well as an all-day tour of the greater Taipei area to gain a better sense of the complex and beautiful culture of Taiwan. Good food and lively talk heightened the enjoyment of the conference

Resolution of the nuclear criticality safety issue for the Hanford site high-level waste tanks

This paper describes the approach used to resolve the Nuclear Criticality Safety Issue for the Hanford Site high-level waste tanks. Although operational controls have been in place at the Hanford Site throughout its operating life to minimize the amount of fissile material discarded as waste, estimates of the total amount of plutonium that entered the waste tanks range from 500 to 1,000 kg. Nuclear criticality safety concerns were heightened in 1991 based on a review of waste analysis results and a subsequent U.S. Department of Energy 1399 review of the nuclear criticality program. Although the DOE review team concluded that there was no imminent risk of a criticality at the Hanford Site tank farms, the team also stated its concern regarding the lack of definitive knowledge of the fissile material inventory and distribution within the waste tanks and the lack of sufficient management support for the overall criticality safety program. An in-depth technical review of the nuclear criticality safety of the waste tanks was conducted to develop a defensible technical basis to ensure that waste tanks are subcritical. The review covered all relevant aspects of nuclear criticality safety including neutronics and chemical and physical phenomena of the waste form under aging waste conditions as well as during routine waste management operations. This paper provides a review of the technical basis to support the conclusion that given current plutonium inventories and operating conditions, a nuclear criticality is incredible. The DOE has been requested to close the Nuclear Criticality Safety Issue. The Defense Nuclear Facilities Safety Board is currently reviewing the technicalbasis

Umweltorientierter Verkehrspolitikwandel in Städten: eine vergleichende Analyse der Innovationsbedingungen von "relativen Erfolgsfällen"

"Im Mittelpunkt der Untersuchung stehen die Voraussetzungen, Inhalte und Folgen von Umweltinnovationen in der kommunaler Verkehrspolitik. Ausgehend von der Beobachtung, daß eine grundlegende 'Ökologisierung' städtischer Verkehrspolitik in den meisten europäischen Städten bislang nicht stattgefunden hat, wird angenommen, daß die Gründe dafür weniger im Fehlen adäquater Verkehrskonzepte, sondern vor allem im Bereich des politischen Wollens und Könnens zu suchen sind. In der kritischen Verkehrswissenschaft werden jedoch einige Städte diskutiert, die als Vorreiter gelten, weil dort umweltorientierte Verkehrskonzepte über längere Zeiträume umgesetzt werden konnten. Diese Ausnahmeerscheinungen bzw. 'relativen Erfolgsfälle' bilden den Gegenstand dieser Untersuchung. Am Beispiel von Amsterdam, Groningen, Zürich und Freiburg i.Br. wird danach gefragt, wie ein umweltorientierter Verkehrspolitikwandel realisiert werden konnte (Policy-Input), wie ökologisch bzw. integriert die umweltorientierte Verkehrspolitik ist (Policy-Output) und inwiefern diese im Hinblick auf eine Verbesserung der Verkehrs- und Umweltbelastungen einen Unterschied macht (Policy-Impact). Es wird ein 3-Phasen-Modell erarbeitet, das die Systematisierung von politischen Innovationsprozessen der kommmunalen Verkehrspolitik ermöglicht, indem es bestimmte Ablaufmuster unterstellt und die Relevanz spezifischer Einflußfaktoren hervorhebt. Die Studie kommt zum Schluß, daß ein umweltorientierter Wandel der kommunalen Verkehrspolitik zwar voraussetzungsvoll, aber grundsätzlich möglich ist. Kommunen können sich sowohl in der Schweiz, in den Niederlanden und in Deutschland für wachstums- oder umweltorientierte Pfade der Verkehrsgestaltung entscheiden. Auch unter derzeitigen Rahmenbedingungen ist die Verkehrsentwicklung in Städten damit innerhalb einer beachtlichen Bandbreite steuerbar." (Autorenreferat)"The paper focuses on the preconditions, contends, and impacts of environmentally-oriented innovations in local transport policy. In spite of the ongoing deterioration of traffic-related environmental problems in European cities, urban transport policy seemed to be extremely resistant to fundamental environmentally-oriented changes. We assume that the main obstacles for achieving an environmentally sustainable transport policy are not lacking knowledge (transport concepts) in the first place, but political will and skill (transport politics). In the 'critical' literature on urban transport policy some cities are discussed as being forerunners, because they are much more successful than most others in implementing 'green' transport policies over longer periods of time. Some of these 'relatively successful cities' are Amsterdam and Groningen (NL), Zurich (CH), and Freiburg (D), which were chosen for case study. It is investigated, how changes in transport policies evolved (Policy-Input), how 'green' the environmentally-oriented urban transport policies really are (Policy-Output), and whether these changes make a difference in terms of reducing car use and improving environmental conditions in these cities (Policy-Impact). A model of transport policy innovations will be outlined, which should enable to systematise the political processes of change of urban transport policy. It assumes, that basic policies changes evolve in three phases, in which different factors and conditions are of special relevance. The study concludes, that fundamental environmentally-oriented policy changes are difficult and requiring, but - on principle - possible. Local governments in Switzerland, the Netherlands and Germany could decide, whether to implement growth-oriented or environmentally-oriented strategies in transport policies. Consequently, local governments are able to influence urban transport trends to a remarkable degree even within the existing framework conditions." (author's abstract

Nuclear criticality project plan for the Hanford Site tank farms

The mission of this project is to provide a defensible technical basis report in support of the Final Safety Analysis Report (FSAR). This technical basis report will also be used to resolve technical issues associated with the nuclear criticality safety issue. The strategy presented in this project plan includes an integrated programmatic and organizational approach. The scope of this project plan includes the provision of a criticality technical basis supporting document (CTBSD) to support the FSAR as well as for resolution of the nuclear criticality safety issue. Specifically, the CTBSD provides the requisite technical analysis to support the FSAR hazard and accident analysis as well as for the determination of the required FSAR limits and controls. The scope of The CTBSD will provide a baseline for understanding waste partitioning and distribution phenomena and mechanistics for current operational activities inclusive of single-shell tanks, double-shell tanks, double-contained receiver tanks, and miscellaneous underground storage tanks.. Although the FSAR does not include future operational activities, the waste partitioning and distribution phenomena and mechanistics work scope identified in this project plan provide a sound technical basis as a point of departure to support independent safety analyses for future activities. The CTBSD also provides the technical basis for resolution of the technical issues associated with the nuclear criticality safety issue. In addition to the CTBSD, additional documentation will be required to fully resolve U.S. Department of Energy-Headquarters administrative and programmatic issues. The strategy and activities defined in this project plan provide a CTBSD for the FSAR and for accelerated resolution of the safety issue in FY 1996. On April 30, 1992, a plant review committee reviewed the Final Safety Analysis Reports for the single-shell, double-shell, and aging waste tanks in light of the conclusions of the inadequate waste characterization with respect to fissile material. The review indicated that the conclusion in the FSARS, that a criticality is not credible, cannot be supported for a full range of potential tank constituents. Therefore, a USQ was declared. Development of a credible scenario leading to a criticality proved to be extremely difficult, given the paucity of data on the quantity and distribution of fissile material in the tanks. The objective of this project plan is to develop a strategy and technical approach to provide a CTBSD for the FSAR and for resolution of the nuclear criticality safety issue pertaining to tank farm waste storage and transfer operations. The strategy and technical approach identified in this project plan include definition of administrative and technical tasks. Technical analyses will include mechanistic studies, historical data review, and additional limited neutronics analysis. Completion of these studies will be documented in a CTBSD to support the existing criticality technical basis. The CTBSD will be incorporated in the criticality portion of the FSAR

Umweltorientierter Verkehrspolitikwandel in Städten: Eine vergleichende Analyse der Innovationsbedingungen von 'relativen Erfolgsfällen'

Im Mittelpunkt der Untersuchung stehen die Voraussetzungen, Inhalte und Folgen von Umweltinnovationen in der kommunaler Verkehrspolitik. Ausgehend von der Beobachtung, daß eine grundlegende „Ökologisierung“ städtischer Verkehrspolitik in den meisten europäischen Städten bislang nicht stattgefunden hat, wird angenommen, daß die Gründe dafür weniger im Fehlen adäquater Verkehrskonzepte, sondern vor allem im Bereich des politischen Wollens und Könnens zu suchen sind. In der kritischen Verkehrswissenschaft werden jedoch einige Städte diskutiert, die als Vorreiter gelten, weil dort umweltorientierte Verkehrskonzepte über längere Zeiträume umgesetzt werden konnten. Diese Ausnahmeerscheinungen bzw. „relativen Erfolgsfälle“ bilden den Gegenstand dieser Untersuchung. Am Beispiel von Amsterdam, Groningen, Zürich und Freiburg i.Br. wird danach gefragt, wie ein umweltorientierter Verkehrspolitikwandel realisiert werden konnte (Policy-Input), wie ökologisch bzw. integriert die umweltorientierte Verkehrspolitik ist (Policy-Output) und inwiefern diese im Hinblick auf eine Verbesserung der Verkehrs- und Umweltbelastungen einen Unterschied macht (Policy-Impact). Es wird ein 3-Phasen-Modell erarbeitet, das die Systematisierung von politischen Innovationsprozessen der kommmunalen Verkehrspolitik ermöglicht, indem es bestimmte Ablaufmuster unterstellt und die Relevanz spezifischer Einflußfaktoren hervorhebt. Die Studie kommt zum Schluß, daß ein umweltorientierter Wandel der kommunalen Verkehrspolitik zwar voraussetzungsvoll, aber grundsätzlich möglich ist. Kommunen können sich sowohl in der Schweiz, in den Niederlanden und in Deutschland für wachstums- oder umweltorientierte Pfade der Verkehrsgestaltung entscheiden. Auch unter derzeitigen Rahmenbedingungen ist die Verkehrsentwicklung in Städten damit innerhalb einer beachtlichen Bandbreite steuerbar. -- The paper focuses on the preconditions, contends, and impacts of environmentallyoriented innovations in local transport policy. In spite of the ongoing deterioration of traffic-related environmental problems in European cities, urban transport policy seemed to be extremely resistant to fundamental environmentally-oriented changes. We assume that the main obstacles for achieving an environmentally sustainable transport policy are not lacking knowledge (transport concepts) in the first place, but political will and skill (transport politics). In the “critical” literature on urban transport policy some cities are discussed as being forerunners, because they are much more successful than most others in implementing “green” transport policies over longer periods of time. Some of these “relatively successful cities” are Amsterdam and Groningen (NL), Zurich (CH), and Freiburg (D), which were chosen for case study. It is investigated, how changes in transport policies evolved (Policy-Input), how “green” the environmentally-oriented urban transport policies really are (PolicyOutput), and whether these changes make a difference in terms of reducing car use and improving environmental conditions in these cities (Policy-Impact). A model of transport policy innovations will be outlined, which should enable to systematise the political processes of change of urban transport policy. It assumes, that basic policies changes evolve in three phases, in which different factors and conditions are of special relevance. The study concludes, that fundamental environmentally-oriented policy changes are difficult and requiring, but - on principle - possible. Local governments in Switzerland, the Netherlands and Germany could decide, whether to implement growth-oriented or environmentally-oriented strategies in transport policies. Consequently, local governments are able to influence urban transport trends to a remarkable degree even within the existing framework conditions.

Sequence-structure correlations in the MaSp1 protein of N. clavipes dragline silk

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 77-86).Silk is a hierarchically structured protein fiber with exceptional tensile strength and extensibility, making it one of the toughest and most versatile biocompatible materials. While experimental studies have shown that the molecular structure of silk has a direct influence on the stiffness, toughness, and failure strength of silk, few molecular-level analyses of the nanostructure of silk assemblies, in particular under variations of genetic sequences, have been published. Here, atomistic-level structures of wildtype as well as modified MaSp1 protein from the N. clavipes spider dragline silk sequences are reported, obtained using an in silico approach based on replica exchange molecular dynamics (REMD) and explicit water molecular dynamics. In particular, the atomistic simulations discussed in this parametric study explore the effects of the poly-alanine length of the N. clavipes MaSpi peptide sequence, solvent conditions, and nanomechanical loading conditions on secondary and tertiary structure predictions as well as the nanomechanical behavior of a unit cell of 15 strands with 900-1000 total residues used to represent a cross-linking 7-sheet crystal node in the network within a fibril of the dragline silk thread. Understanding the behavior of this node at the molecular scale is critical for potentially bypassing strength limits at this length scale and vastly improving silk for medical and textile purposes as well as synthetic elastomers and polymer or aramid fiber composites with a similar molecular structure and noncovalent bonding for aerospace, armor, and medical applications. The main hypothesis tested is that there exists a critical minimum length of the poly-alanine repeat that ensures the formation of a robust cross-linking the [beta]-sheet crystal. Confirming earlier experimental and computational work, a structural analysis reveals that poly-alanine regions in silk predominantly form distinct and orderly [beta]-sheet crystal domains while disorderly regions are formed by glycine-rich repeats that consist of 310-helix type structures and 7-turns. These predictions are directly validated against experimental data based on dihedral angle pair calculations presented in Ramachandran plots combined with an analysis of the secondary structure content. The key results of this study are: e A strong dependence of the resulting silk nanostructure on the poly-alanine length. The wildtype poly-alanine repeat length of six residues defines a critical minimum length that consistently results in clearly defined [beta]-sheet nanocrystals allowing for misalignment. For poly-alanine lengths below six residues, the /-sheet nanocrystals are not well-defined or not visible at all, while for poly-alanine lengths above six the characteristic nanocomposite structure of silk emerges with no significant improvement of the quality of the sheet nanocrystal geometry. A simple biophysical model is presented that explains the minimum length scale based on the mechanistic insight gained from the molecular simulations. The efficient stacking of the [beta]-sheets of a well-defined crystal reinforces local hydrophobicity and prevents water diffusion into a crystal above a critical size. Nanomechanical testing reveals that the combination of the 12-alanine length case and central pull-out loading conditions results in delayed failure by employing a hierarchy of strong [beta]-sheets and soft, extensible semi-amorpous regions to overcome a predicted H-bond saturation. This work constitutes the most comprehensive study to-date of the molecular structure prediction and nanomechanical behavior of dragline silk. Building upon previous computational studies that used similar methods for structure prediction and mechanical analysis, e.g. REMD and force-control loading, this work presents: the first results of the near-native structures determined by REMD after equilibration in TIP3P explicit solvent, the first parametric study of the effects of modifying the wildtype poly-alanine segment length to values outside the range naturally observed for MaSp1 on structure prediction and nanomechanical behavior, and, the first comparison between previously published loading conditions, i.e. the Stretch test, and the novel Pull-out loading conditions that are hypothesized to be more appropriate for modeling of the in situ loading of the cross-linking [beta]-sheet crystal. Further parametric studies in peptide sequence to optimize bulk fiber properties must involve changes in simulated nanomechanical loading conditions to properly assess the effects of the changes in peptide sequence. These findings set the stage for understanding how variations in the spidroin sequence can be used to engineer the structure and thereby functional properties of this biological superfiber, and present a design strategy for the genetic optimization of spidroins for enhanced mechanical properties. The approach used here may also find application in the design of other self-assembled molecular structures and fibers and in particular biologically inspired or completely synthetic systems.by Graham Hayden Bratzel.S.M

Tank 241-SX-106 headspace gas and vapor characterization results for samples collected in March 1995

Significant changes have been made to all of the original vapor characterization reports. This report documents specific headspace gas and vapor characterization results for all vapor sampling events to date. In addition, changes have been made to the original vapor reports to qualify the data based on quality assurance issues associated with the performing laboratories