Gone with transgenic cotton cropping in the USA. A perception of the presentations and interactions at the Beltwide Cotton Conferences, New Orleans (Louisiana, USA), 4-7/01/2010

The 2010 Beltwide Cotton Conferences provided a new vision of the consequences of about 15 years of widespread and uncoordinated cropping of transgenic cotton in the United States. Insect-resistant and/or herbicide-tolerant cotton varieties modified parasite complexes, namely those of insects and weeds damaging cotton crops. The Conferences have revealed that the adaptation solutions so far proposed make illusory the expectations at the launch of transgenic cotton, in terms of effective pest control, cost reduction, and antagonism between chemical and biotech methods. The USA case points out that the technical and economic sustainability of transgenic varieties must lie in a systemic and coordinated approach

Do National Culture and Organizational Development Affect the Effectiveness of ERP Implementation? A Tale of Two Cultures: US versus China

As many US and European companies have implemented Enterprise Resource Planning (ERP) Systems, most of the previous implementation studies have tended to focus on companies from more developed countries. This research points out that there is need for academics and practitioners to “take stock,” to examine what is happening in broad terms across organizations in the ERP implementation process, and to consider whether cultural differences in the U.S. when compared to another culture can impact the process. In this study, we are concerned with several issues surrounding current ERP implementation status and report initial findings from managers in a wide variety of organizations in the U.S. and China on their experiences with ERP implementation and attempt to suggest implications. Our findings center upon cultural differences, especially in the reported context surrounding ERP implementation in the two cultures. Moreover, we report that there is evidence for differences in ERP complexity and implementation extensiveness in the two cultures. Finally, we find some evidence for differences in reported outcomes. We include suggestions for future research

Buildup of the ring current during periodic loading‐unloading cycles in the magnetotail driven by steady southward interplanetary magnetic field

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95239/1/jgra18825.pd

Plasmasphere Modeling with Ring Current Heating

Coulomb collisions between ring current ions and the thermal plasma in the plasmasphere will heat the plasmaspheric electrons and ions. During a storm such heating would lead to significant changes in the temperature and density of the thermal plasma. This was modeled using a time- dependent, one-stream hydrodynamic model for plasmaspheric flows, in which the model flux tube is connected to the ionosphere. The model simultaneously solves the coupled continuity, momentum, and energy equations of a two-ion (H(+) and O(+) quasineutral, currentless plasma. Heating rates due to collisions with ring current ions were calculated along the field line using a kinetic ring current model. First, diurnally reproducible results were found assuming only photoelectron heating of the thermal electrons. Then results were found with heating of the H(+) ions by the ring current during the recovery phase of a magnetic storm

Long span steel pedestrian bridge at Singapore Changi Airport - part 1: Prediction of vibration serviceability problems

Changi Mezzanine Bridge is a 140m span flat arch footbridge constructed from welded tubular steel sections inside a tunnel that connects two passenger terminals at Changi Airport, Singapore. A series of vibration measurements were made on the bridge during construction, showing that non-structural cladding added mass and reduced the natural frequencies while also increasing the modal damping, from as little as 0.2% originally to around 0.4% for critical vibration modes. From these preliminary studies leading up to the opening of the bridge in early 2002, it was clear that the first symmetric lateral vibration mode (LS1) at approximately 0.9Hz and the first symmetric torsional vibration mode (TS1) at approximately 1.64Hz could be excited easily by pedestrian movement. The modal parameters for mode LS1 suggested that the bridge could suffer from synchronous lateral excitation for a walking pace of 1.8Hz while for TS1 the potential problem was the coincidence of the mode frequency with the lower range of predominant footfall frequencies together with a very low modal mass. These possibilities had been identified by the consultant who advised that an experimental study of the characteristics of low frequency vibration modes should be conducted to check vibration serviceability predictions based on analytical modeling. Forced vibration testing using a combination of shakers and humans was used to determine in a very short time scale, the properties for modes below 3Hz. The mode shapes and frequencies compared favourably with predictions from the consultant’s finite element model that had been used to show that with a large number of pedestrians, comfort levels would be exceeded and the bridge would be unserviceable

Long span steel pedestrian bridge at Singapore Changi Airport. Part 2: Crowd loading tests and vibration mitigation measures

issue: 16article© Copyright The Institution of Structural EngineersFollowing experimental and analytical studies of vibration serviceability of a 140m span steel footbridge which predicted excessive and uncomfortable vertical and lateral vibration levels due to crowd loading, a series of walking tests involving up to 150 pedestrians was aimed at assessing the prototype behaviour under ‘limiting typical’ pedestrian loads in two vibration modes judged to be critical. In a walking test for possible instability resulting from so-called ‘synchronous lateral excitation’ (SLE), pedestrian volunteers were fed onto the bridge and told to walk casually. With all 150 available pedestrians circulating for several minutes, a steady increase in lateral vibrations was observed. This divergent response resembled the phenomenon observed during tests on the London Millennium Bridge (LMB), and while the maximum response reported here was an order of magnitude smaller than the largest levels reported for LMB on its opening day it was, apparently, uncomfortable for pedestrians. On the other hand, due to the apparent lack of synchronisation and random character of vertical loads together with enhanced damping due to the pedestrians themselves, vertical response levels were within acceptable comfort limits. From observations of pedestrian movement and the nature of response in vertical and lateral modes there appears to be an open question about the nature of any possible synchronisation of forces and the manner of generating and building up relatively large lateral amplitudes. To mitigate the potential for strong and unsafe lateral oscillation in the unlikely event of larger numbers of pedestrians, a tuned mass damping system has been installed. The damping in LS1 has been increased by a factor of approximately four, so that SLE is effectively prevented for any foreseeable reasonable pedestrian loading

Dynamic Boundaries in Asymmetric Exclusion Processes

We investigate the dynamics of a one-dimensional asymmetric exclusion process with Langmuir kinetics and a fluctuating wall. At the left boundary, particles are injected onto the lattice; from there, the particles hop to the right. Along the lattice, particles can adsorb or desorb, and the right boundary is defined by a wall particle. The confining wall particle has intrinsic forward and backward hopping, a net leftward drift, and cannot desorb. Performing Monte Carlo simulations and using a moving-frame finite segment approach coupled to mean field theory, we find the parameter regimes in which the wall acquires a steady state position. In other regimes, the wall will either drift to the left and fall off the lattice at the injection site, or drift indefinitely to the right. Our results are discussed in the context of non-equilibrium phases of the system, fluctuating boundary layers, and particle densities in the lab frame versus the frame of the fluctuating wall.Comment: 13 page

The ionospheric outflow feedback loop

AbstractFollowing a long period of observation and investigation beginning in the early 1970s, it has been firmly established that Earth׳s magnetosphere is defined as much by the geogenic plasma within it as by the geomagnetic field. This plasma is not confined to the ionosphere proper, defined as the region within a few density scale heights of the F-region plasma density peak. Rather, it fills the flux tubes on which it is created, and circulates throughout the magnetosphere in a pattern driven by solar wind plasma that becomes magnetically connected to the ionosphere by reconnection through the dayside magnetopause. Under certain solar wind conditions, plasma and field energy is stored in the magnetotail rather than being smoothly recirculated back to the dayside. Its release into the downstream solar wind is produced by magnetotail disconnection of stored plasma and fields both continuously and in the form of discrete plasmoids, with associated generation of energetic Earthward-moving bursty bulk flows and injection fronts. A new generation of global circulation models is showing us that outflowing ionospheric plasmas, especially O+, load the system in a different way than the resistive F-region load of currents dissipating energy in the plasma and atmospheric neutral gas. The extended ionospheric load is reactive to the primary dissipation, forming a time-delayed feedback loop within the system. That sets up or intensifies bursty transient behaviors that would be weaker or absent if the ionosphere did not “strike back” when stimulated. Understanding this response appears to be a necessary, if not sufficient, condition for us to gain accurate predictive capability for space weather. However, full predictive understanding of outflow and incorporation into global simulations requires a clear observational and theoretical identification of the causal mechanisms of the outflows. This remains elusive and requires a dedicated mission effort

Structure d’allocation de la main-d’œuvre familiale dans les menages agricoles dans le departement de l’alibori au Nord-Benin

Dans la zone cotonnière Béninoise, les facteurs de production travail et terre constituent les principaux moyens d’existence des paysans. Toute la vie des ménages est centrée sur l’exploitation agricole, qui mobilise hommes et femmes, membres de la famille et de la communauté comme main-d’œuvre. Dans cet article, il est analysé pour deux communes rurales du département de l’Alibori au Nord du Bénin, la mise en œuvre des différentes stratégies d’allocation de la main-d’œuvre familiale des ménages. Pour cela, un total de 300 ménages agricoles a été échantillonné par leurs chefs d’exploitation, de façon aléatoire et raisonnée. En utilisant les statistiques descriptives et les tests de comparaison de moyennes, les résultats montrent que l’organisation actuelle des activités et la gestion du temps sont fonction de la structure des ménages et de certaines spéculations et activités prioritaires pour les membres. Cette division de travail permet d’assurer à la fois la continuité de l’exploitation agricole, l’exercice de certaines activités extra-agricoles, la survie de la famille et la cohésion sociale.   English title: Allocation structure of family labor in agricultural households in Alibori department in northen Benin In the cotton zone of Benin, labor and land production factors constitute the main means of farmer’s existence. The whole life of households is centered on farming, which mobilizes men and women, family and community members as a labor force. In this paper, it analyzes the implementation of the different strategies for allocating family labor to households in two rural communes in the Alibori department in Northern Benin. To achieve this objective, a survey mobilized 300 cotton-producing farm households randomly and reasoned identified. Using descriptive statistics and mean comparison tests, the results show that the current organization of activities and time management are a function of household structure and some speculation and priority activities for members. This division of labor ensures the continuity of farming, the exercise of certain non-agricultural activities, family survival and social cohesion. &nbsp

Effect of multiple substorms on the buildup of the ring current

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95361/1/jgra17662.pd