NEW CURRENTS AND NEW CONCEPTS IN COMMUNITY DEVELOPMENT

Community/Rural/Urban Development,

Design method for adsorption beds

Regenerable adsorption beds for long-term life support systems include synthetic geolite to remove carbon dioxide and silica gel to dehumidify the atmospheric gas prior to its passage through the geolite beds. Bed performance is evaluated from adsorption characteristics, heat and mass transfer, and pressure drop

High Speed Chaos in Optical Feedback System with Flexible Timescales

We describe a new opto-electronic device with time-delayed feedback that uses a Mach-Zehnder interferometer as passive nonlinearity and a semiconductor laser as a current-to-optical-frequency converter. Bandlimited feedback allows tuning of the characteristic time scales of both the periodic and high dimensional chaotic oscillations that can be generated with the device. Our implementation of the device produces oscillations in the frequency range of tens to hundreds of MHz. We develop a model and use it to explore the experimentally observed Andronov-Hopf bifurcation of the steady state and to estimate the dimension of the chaotic attractor.Comment: 7 pages, 6 figures, to be published in IEEE J. Quantum Electro

The Secreted Acid Phosphatase Domain-Containing GRA44 from Toxoplasma gondii Is Required for c-Myc Induction in Infected Cells.

During host cell invasion, the eukaryotic pathogen Toxoplasma gondii forms a parasitophorous vacuole to safely reside within the cell, while it is partitioned from host cell defense mechanisms. From within this safe niche, parasites sabotage multiple host cell systems, including gene expression, apoptosis, and intracellular immune recognition, by secreting a large arsenal of effector proteins. Many parasite proteins studied for active host cell manipulative interactions have been kinases. The translocation of effectors from the parasitophorous vacuole into the host cell is mediated by a putative translocon complex, which includes the proteins MYR1, MYR2, and MYR3. Whether other proteins are involved in the structure or regulation of this putative translocon is not known. We have discovered that the secreted protein GRA44, which contains a putative acid phosphatase domain, interacts with members of this complex and is required for host cell effects downstream of effector secretion. We have determined that GRA44 is processed in a region with homology to sequences targeted by protozoan proteases of the secretory pathway and that both major cleavage fragments are secreted into the parasitophorous vacuole. Immunoprecipitation experiments showed that GRA44 interacts with a large number of secreted proteins, including MYR1. Importantly, conditional knockdown of GRA44 resulted in a lack of host cell c-Myc upregulation, which mimics the phenotype seen when members of the translocon complex are genetically disrupted. Thus, the putative acid phosphatase GRA44 is crucial for host cell alterations during Toxoplasma infection and is associated with the translocon complex which Toxoplasma relies upon for success as an intracellular pathogen.IMPORTANCE Approximately one-third of humans are infected with the parasite Toxoplasma gondii Toxoplasma infections can lead to severe disease in those with a compromised or suppressed immune system. Additionally, infections during pregnancy present a significant health risk to the developing fetus. Drugs that target this parasite are limited, have significant side effects, and do not target all disease stages. Thus, a thorough understanding of how the parasite propagates within a host is critical in the discovery of novel therapeutic targets. Toxoplasma replication requires that it enter the cells of the infected organism. In order to survive the environment inside a cell, Toxoplasma secretes a large repertoire of proteins, which hijack a number of important cellular functions. How these Toxoplasma proteins move from the parasite into the host cell is not well understood. Our work shows that the putative phosphatase GRA44 is part of a protein complex responsible for this process

Identification and characterization of the dif Site from Bacillus subtilis

Bacteria with circular chromosomes have evolved systems that ensure multimeric chromosomes, formed by homologous recombination between sister chromosomes during DNA replication, are resolved to monomers prior to cell division. The chromosome dimer resolution process in Escherichia coli is mediated by two tyrosine family site-specific recombinases, XerC and XerD, and requires septal localization of the division protein FtsK. The Xer recombinases act near the terminus of chromosome replication at a site known as dif (Ecdif). In Bacillus subtilis the RipX and CodV site-specific recombinases have been implicated in an analogous reaction. We present here genetic and biochemical evidence that a 28-bp sequence of DNA (Bsdif), lying 6° counterclockwise from the B. subtilis terminus of replication (172°), is the site at which RipX and CodV catalyze site-specific recombination reactions required for normal chromosome partitioning. Bsdif in vivo recombination did not require the B. subtilis FtsK homologues, SpoIIIE and YtpT. We also show that the presence or absence of the B. subtilis SPβ-bacteriophage, and in particular its yopP gene product, appears to strongly modulate the extent of the partitioning defects seen in codV strains and, to a lesser extent, those seen in ripX and dif strains

High effectiveness contour matching contact heat exchanger

There is a need in the art for a heat exchanger design having a flexible core providing contour matching capabilities, which compensates for manufacturing tolerance and distortion buildups, and which accordingly furnishes a relatively uniform thermal contact conductance between the core and external heat sources under essentially all operating conditions. The core of the heat exchanger comprises a top plate and a bottom plate, each having alternate rows of pins attached. Each of the pins fits into corresponding tight-fitting recesses in the opposite plate

Recovery of the soul: sustainable rebuilding in post-Katrina New Orleans

Although the notion of sustainable development is usually associated with the design and building of new settlements, this chapter illustrates how this notion can also be used to undergird the recovery strategies to rebuild a city struck by a natural disaster. The chapter shows how a sustainable development approach in post-Katrina New Orleans has helped frame post-disaster recovery efforts by applying the following five sustainability concepts: community participation in deciding best strategies for recovery to continue the healing; public safety and security for all neighbourhoods; 100-plus-year time-horizon infrastructure planning; a diverse economy; and sustainable settlement pattern

Disagreeable, Villainous, and Wimpy: The Child as Antihero in Burnett, Colfer, and Kinney

Although children’s literature is often dismissed as largely didactic and supportive of entrenched power structures, an examination of the antihero’s development in children’s literature reveals the genre’s complexity and subtle challenges of social mores. Critics focus extensive attention on the redemption of a less-than-ideal character from social deviancy to normalcy in fiction for young readers, but more rarely do they discuss those characters that remain static in their lack of heroic qualities and fail as role models for children. The on-going discussion on conventional subgenres like the school story does not often include texts that subvert the form with bullying or “wimpy” protagonists. Most significantly, the debate over the role of children’s literature in maintaining or questioning adult authority often passes over books that show children committing immoral actions usually reserved for adults. In the following pages, I place the ironic mode and the antihero into the context of literature for children, focusing primarily on a close reading of three texts from British and American writers in the twentieth and twenty-first centuries: The Secret Garden by Frances Hodgson Burnett, Artemis Fowl by Eoin Colfer, and Diary of a Wimpy Kid by Jeff Kinney. Each of the protagonists will be examined in light of the cultural contexts of the writers, the overall messages of the books, and the stories’ relationships to existing genre conventions. My research draws conclusions about when the child antihero emerges in literary history, how the antihero helps communicate the writer’s message about a particular issue or society in general, and why a writer chooses for the antihero to find redemption or not. Together, the three novels provide a fascinating look at how children’s novels depart from tradition yet remain very much a part of a literary canon