Solomon Islands: Essential aspects of governance for Aquatic Agricultural Systems in Malaita Hub

In late 2012, a governance assessment was carried out as part of the diagnosis phase of rollout of the CGIAR Aquatic Agricultural Systems Program in Malaita Hub in Solomon Islands. The purpose of the assessment was to identify and provide a basic understanding of essential aspects of governance related to Aquatic Agricultural Systems in general, and more specifically as a case study in natural resource management. The underlying principles of the approach we have taken are drawn from an approach known as “Collaborating for Resilience” (CORE), which is based on bringing all key stakeholders into a process to ensure that multiple perspectives are represented (a listening phase), that local actors have opportunities to influence each other’s understanding (a dialogue phase), and that ultimately commitments to action are built (a choice phase) that would not be possible through an outsider’s analysis alone. This report begins to address governance from an AAS perspective, using input from AAS households and other networked stakeholders. We attempt to summarize governance issues that are found not only within the community but also, and especially, those that are beyond the local level, both of which may need to be addressed by the AAS program

AFM pulling and the folding of donor-acceptor oligorotaxanes: phenomenology and interpretation

The thermodynamic driving force in the self-assembly of the secondary structure of a class of donor-acceptor oligorotaxanes is elucidated by means of molecular dynamics simulations of equilibrium isometric single-molecule force spectroscopy AFM experiments. The oligorotaxanes consist of cyclobis(paraquat-\emph{p}-phenylene) rings threaded onto an oligomer of 1,5-dioxynaphthalenes linked by polyethers. The simulations are performed in a high dielectric medium using MM3 as the force field. The resulting force vs. extension isotherms show a mechanically unstable region in which the molecule unfolds and, for selected extensions, blinks in the force measurements between a high-force and a low-force regime. From the force vs. extension data the molecular potential of mean force is reconstructed using the weighted histogram analysis method and decomposed into energetic and entropic contributions. The simulations indicate that the folding of the oligorotaxanes is energetically favored but entropically penalized, with the energetic contributions overcoming the entropy penalty and effectively driving the self-assembly. In addition, an analogy between the single-molecule folding/unfolding events driven by the AFM tip and the thermodynamic theory of first-order phase transitions is discussed and general conditions, on the molecule and the cantilever, for the emergence of mechanical instabilities and blinks in the force measurements in equilibrium isometric pulling experiments are presented. In particular, it is shown that the mechanical stability properties observed during the extension are intimately related to the fluctuations in the force measurements.Comment: 42 pages, 17 figures, accepted to the Journal of Chemical Physic

Anthrax Toxin Uptake by Primary Immune Cells as Determined with a Lethal Factor-β-Lactamase Fusion Protein

BACKGROUND:To initiate infection, Bacillus anthracis needs to overcome the host innate immune system. Anthrax toxin, a major virulence factor of B. anthracis, impairs both the innate and adaptive immune systems and is important in the establishment of anthrax infections. METHODOLOGY/PRINCIPAL FINDINGS:To measure the ability of anthrax toxin to target immune cells, studies were performed using a fusion of the anthrax toxin lethal factor (LF) N-terminal domain (LFn, aa 1-254) with beta-lactamase (LFnBLA). This protein reports on the ability of the anthrax toxin protective antigen (PA) to mediate LF delivery into cells. Primary immune cells prepared from mouse spleens were used in conjunction with flow cytometry to assess cleavage and resulting FRET disruption of a fluorescent beta-lactamase substrate, CCF2/AM. In spleen cell suspensions, the macrophages, dendritic cells, and B cells showed about 75% FRET disruption of CCF2/AM due to cleavage by the PA-delivered LFnBLA. LFnBLA delivery into CD4+ and CD8+ T cells was lower, with 40% FRET disruption. When the analyses were done on purified samples of individual cell types, similar results were obtained, with T cells again having lower LFnBLA delivery than macrophages, dendritic cells, and B cells. Relative expression levels of the toxin receptors CMG2 and TEM8 on these cells were determined by real-time PCR. Expression of CMG2 was about 1.5-fold higher in CD8+ cells than in CD4+ and B cells, and 2.5-fold higher than in macrophages. CONCLUSIONS/SIGNIFICANCE:Anthrax toxin entry and activity differs among immune cells. Macrophages, dendritic cells, and B cells displayed higher LFnBLA activity than CD4+ and CD8+ T cells in both spleen cell suspension and the purified samples of individual cell types. Expression of anthrax toxin receptor CMG2 is higher in CD4+ and CD8+ T cells, which is not correlated to the intracellular LFnBLA activity

Design of a fault tolerant airborne digital computer. Volume 2: Computational requirements and technology

This final report summarizes the work on the design of a fault tolerant digital computer for aircraft. Volume 2 is composed of two parts. Part 1 is concerned with the computational requirements associated with an advanced commercial aircraft. Part 2 reviews the technology that will be available for the implementation of the computer in the 1975-1985 period. With regard to the computation task 26 computations have been categorized according to computational load, memory requirements, criticality, permitted down-time, and the need to save data in order to effect a roll-back. The technology part stresses the impact of large scale integration (LSI) on the realization of logic and memory. Also considered was module interconnection possibilities so as to minimize fault propagation

Neurofibromatosis type 1: Modeling CNS dysfunction

Neurofibromatosis type 1 (NF1) is the most common monogenic disorder in which individuals manifest central nervous system (CNS) abnormalities. Affected individuals develop glial neoplasms (optic gliomas, malignant astrocytomas) and neuronal dysfunction (learning disabilities, attention deficits). Nf1 genetically-engineered mouse models have revealed the molecular and cellular underpinnings of gliomagenesis, attention deficit, and learning problems with relevance to basic neurobiology. Using NF1 as a model system, these studies have revealed critical roles for the NF1 gene in non-neoplastic cells in the tumor microenvironment, the importance of brain region heterogeneity, novel mechanisms of glial growth regulation, the neurochemical bases for attention deficit and learning abnormalities, and new insights into neural stem cell function. Here we review recent studies, presented at a symposium at the 2012 Society for Neuroscience annual meeting, that highlight unexpected cell biology insights into RAS and cyclic AMP pathway effects on neural progenitor signaling, neuronal function, and oligodendrocyte lineage differentiation

Molecular transport junctions: Current from electronic excitations in the leads

Using a model comprising a 2-level bridge connecting free electron reservoirs we show that coupling of a molecular bridge to electron-hole excitations in the leads can markedly effect the source-drain current through a molecular junction.In some cases, e.g. molecules that exhibit strong charge transfer transitions, the contribution from electron-hole excitations can exceed the Landauer elastic current and dominate the observed conduction.Comment: 4 pages, 2 figures, submitted to PR

Inelastic effects in molecular junctions in the Coulomb and Kondo regimes: Nonequilibrium equation-of-motion approach

Inelastic effects in the Coulomb blockade and Kondo regimes of electron transport through molecular junctions are considered within a simple nonequilibrium equation-of-motion (EOM) approach. The scheme is self-consistent, and can qualitatively reproduce the main experimental observations of vibrational features in Coulomb blockade [H.Park et al., Nature 407, 57 (2000)] and Kondo [L.H.Yu et al., Phys. Rev. Lett. 93, 266802 (2004)] regimes. Considerations similar to the equilibrium EOM approach by Meir et al. [Phys. Rev. Lett. 66, 3048 (1991); ibid. 70, 2601 (1993)] are used on the Keldysh contour to account for the nonequilibrium nature of the junction, and dressing by appropriate Franck-Condon (FC) factors is used to account for vibrational features. Results of the equilibrium EOM scheme by Meir et al. are reproduced in the appropriate limit.Comment: 12 pages, 5 figure

Construction of the GAMCIT gamma-ray burst detector (G-056)

The GAMCIT (Gamma-ray Astrophysics Mission, California Institute of Technology) payload is a Get-Away-Special payload designed to search for high-energy gamma-ray bursts and any associated optical transients. This paper presents details on the development and construction of the GAMCIT payload. In addition, this paper will reflect upon the unique challenges involved in bringing the payload close to completion, as the project has been designed, constructed, and managed entirely by undergraduate members of the Caltech SEDS (Students for the Exploration and Development of Space). Our experience will definitely be valuable to other student groups interested in undertaking a challenge such as a Get-Away-Special payload

The Induction of Colitis and Ileitis in Mice Is Associated with Marked Increases in Intestinal Concentrations of Stimulants of TLRs 2, 4, and 5

Peer reviewedPublisher PD

Cooperative effects in nuclear excitation with coherent x-ray light

The interaction between super-intense coherent x-ray light and nuclei is studied theoretically. One of the main difficulties with driving nuclear transitions arises from the very narrow nuclear excited state widths which limit the coupling between laser and nuclei. In the context of direct laser-nucleus interaction, we consider the nuclear width broadening that occurs when in solid targets, the excitation caused by a single photon is shared by a large number of nuclei, forming a collective excited state. Our results show that for certain isotopes, cooperative effects may lead to an enhancement of the nuclear excited state population by almost two orders of magnitude. Additionally, an update of previous estimates for nuclear excited state population and signal photons taking into account the experimental advances of the x-ray coherent light sources is given. The presented values are an improvement by orders of magnitude and are encouraging for the future prospects of nuclear quantum optics.Comment: 22 pages, 4 figures, 5 tables; updated to the published version, one additional results tabl