Performance Assessment of Pressurized Stairs in High Rise Buildings

Research paper published in the journal Fire Technology, special issue on Smoke Control in Buildings and Tunnels.Pressurized stair cases are an important part of the fire safety strategy of high rise buildings. Long egress times are compensated by creating safe environments within egress staircases allowing the displacement time within those stairs as time where occupants can be considered safe. The main mechanisms by which stairs are ‘‘made safe’’ are by guaranteeing structural protection of the enclosure and by elevating the pressure within the stair to ensure that smoke cannot enter. Despite the critical importance of this element of the fire safety strategy, the analysis and implementation of these systems remain simplified. Simple models have been developed using Bernoulli type formulations that account for static pressure and empirical constants to calculate flows through doors and other leakage areas. Implementation of these systems is even more simplified, consisting mainly of a direct feedback loop that controls a fan output on the basis of a pressure measurement inside the stair. The flow induced by the fan guarantees a minimum pressure. The pressure inside the stair needs to be limited to enable doors to be open, thus pressure dampers are introduced to release airflow in the event the pressure exceeds a specified maximum. Validation of these methodologies was done in the 70s and 80s with very limited field validation in real systems. This study presents an assessment of the performance of pressurized staircases in six high rise buildings. All systems have been designed using a similar methodology but implemented in different ways. In all cases the control mechanism for the fan is a direct feedback loop from a single pressure sensor. The results have been evaluated showing the limitations of the control system in the event of multiple doors being opened and the limitations of the pressure release dampers (as a response mechanism) if the pressure becomes unstable

Lymphoid Organ-Resident Dendritic Cells Exhibit Unique Transcriptional Fingerprints Based on Subset and Site

Lymphoid organ-resident DC subsets are thought to play unique roles in determining the fate of T cell responses. Recent studies focusing on a single lymphoid organ identified molecular pathways that are differentially operative in each DC subset and led to the assumption that a given DC subset would more or less exhibit the same genomic and functional profiles throughout the body. Whether the local milieu in different anatomical sites can also influence the transcriptome of DC subsets has remained largely unexplored. Here, we interrogated the transcriptional relationships between lymphoid organ-resident DC subsets from spleen, gut- and skin-draining lymph nodes, and thymus of C57BL/6 mice. For this purpose, major resident DC subsets including CD4 and CD8 DCs were sorted at high purity and gene expression profiles were compared using microarray analysis. This investigation revealed that lymphoid organ-resident DC subsets exhibit divergent genomic programs across lymphoid organs. Interestingly, we also found that transcriptional and biochemical properties of a given DC subset can differ between lymphoid organs for lymphoid organ-resident DC subsets, but not plasmacytoid DCs, suggesting that determinants of the tissue milieu program resident DCs for essential site-specific functions

Mn 2+ reduces Y z + in manganese-depleted Photosystem II preparations

Manganese in the oxygen-evolving complex is a physiological electron donor to Photosystem II. PS II depleted of manganese may oxidize exogenous reductants including benzidine and Mn 2+ . Using flash photolysis with electron spin resonance detection, we examined the room-temperature reaction kinetics of these reductants with Y z + , the tyrosine radical formed in PS II membranes under illumination. Kinetics were measured with membranes that did or did not contain the 33 kDa extrinsic polypeptide of PS II, whose presence had no effect on the reaction kinetics with either reductant. The rate of Y z + reduction by benzidine was a linear function of benzidine concentration. The rate of Y z + reduction by Mn 2+ at pH 6 increased linearly at low Mn 2+ concentrations and reached a maximum at the Mn 2+ concentrations equal to several times the reaction center concentration. The rate was inhibited by K + , Ca 2+ and Mg 2+ . These data are described by a model in which negative charge on the membrane causes a local increase in the cation concentration. The rate of Y z + reduction at pH 7.5 was biphasic with a fast 400 μs phase that suggests binding of Mn 2+ near Y z + at a site that may be one of the native manganese binding sites.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43534/1/11120_2004_Article_BF00048306.pd

Molecular Evolution of the Rice Blast Resistance Gene Pi-ta in Invasive Weedy Rice in the USA

The Pi-ta gene in rice has been effectively used to control rice blast disease caused by Magnaporthe oryzae worldwide. Despite a number of studies that reported the Pi-ta gene in domesticated rice and wild species, little is known about how the Pi-ta gene has evolved in US weedy rice, a major weed of rice. To investigate the genome organization of the Pi-ta gene in weedy rice and its relationship to gene flow between cultivated and weedy rice in the US, we analyzed nucleotide sequence variation at the Pi-ta gene and its surrounding 2 Mb region in 156 weedy, domesticated and wild rice relatives. We found that the region at and around the Pi-ta gene shows very low genetic diversity in US weedy rice. The patterns of molecular diversity in weeds are more similar to cultivated rice (indica and aus), which have never been cultivated in the US, rather than the wild rice species, Oryza rufipogon. In addition, the resistant Pi-ta allele (Pi-ta) found in the majority of US weedy rice belongs to the weedy group strawhull awnless (SH), suggesting a single source of origin for Pi-ta. Weeds with Pi-ta were resistant to two M. oryzae races, IC17 and IB49, except for three accessions, suggesting that component(s) required for the Pi-ta mediated resistance may be missing in these accessions. Signatures of flanking sequences of the Pi-ta gene and SSR markers on chromosome 12 suggest that the susceptible pi-ta allele (pi-ta), not Pi-ta, has been introgressed from cultivated to weedy rice by out-crossing

Effects of dietary Na+ deprivation on epithelial Na+ channel (ENaC), BDNF, and TrkB mRNA expression in the rat tongue

<p>Abstract</p> <p>Background</p> <p>In rodents, dietary Na⁺deprivation reduces gustatory responses of primary taste fibers and central taste neurons to lingual Na⁺stimulation. However, in the rat taste bud cells Na⁺deprivation increases the number of amiloride sensitive epithelial Na⁺channels (ENaC), which are considered as the "receptor" of the Na⁺component of salt taste. To explore the mechanisms, the expression of the three ENaC subunits (α, β and γ) in taste buds were observed from rats fed with diets containing either 0.03% (Na⁺deprivation) or 1% (control) NaCl for 15 days, by using <it>in situ </it>hybridization and real-time quantitative RT-PCR (qRT-PCR). Since BDNF/TrkB signaling is involved in the neural innervation of taste buds, the effects of Na⁺deprivation on BDNF and its receptor TrkB expression in the rat taste buds were also examined.</p> <p>Results</p> <p><it>In situ </it>hybridization analysis showed that all three ENaC subunit mRNAs were found in the rat fungiform taste buds and lingual epithelia, but in the vallate and foliate taste buds, only α ENaC mRNA was easily detected, while β and γ ENaC mRNAs were much less than those in the fungiform taste buds. Between control and low Na⁺fed animals, the numbers of taste bud cells expressing α, β and γ ENaC subunits were not significantly different in the fungiform, vallate and foliate taste buds, respectively. Similarly, qRT-PCR also indicated that Na⁺deprivation had no effect on any ENaC subunit expression in the three types of taste buds. However, Na⁺deprivation reduced BDNF mRNA expression by 50% in the fungiform taste buds, but not in the vallate and foliate taste buds. The expression of TrkB was not different between control and Na⁺deprived rats, irrespective of the taste papillae type.</p> <p>Conclusion</p> <p>The findings demonstrate that dietary Na⁺deprivation does not change ENaC mRNA expression in rat taste buds, but reduces BDNF mRNA expression in the fungiform taste buds. Given the roles of BDNF in survival of cells and target innervation, our results suggest that dietary Na⁺deprivation might lead to a loss of gustatory innervation in the mouse fungiform taste buds.</p

Virulence of 32 Salmonella Strains in Mice

Virulence and persistence in the BALB/c mouse gut was tested for 32 strains of Salmonella enterica for which genome sequencing is complete or underway, including 17 serovars within subspecies I (enterica), and two representatives of each of the other five subspecies. Only serovar Paratyphi C strain BAA1715 and serovar Typhimurium strain 14028 were fully virulent in mice. Three divergent atypical Enteritidis strains were not virulent in BALB/c, but two efficiently persisted. Most of the other strains in all six subspecies persisted in the mouse intestinal tract for several weeks in multiple repeat experiments although the frequency and level of persistence varied considerably. Strains with heavily degraded genomes persisted very poorly, if at all. None of the strains tested provided immunity to Typhimurium infection. These data greatly expand on the known significant strain-to-strain variation in mouse virulence and highlight the need for comparative genomic and phenotypic studies

Preferential Amplification of CD8 Effector-T Cells after Transcutaneous Application of an Inactivated Influenza Vaccine: A Randomized Phase I Trial

Background: Current conventional vaccination approaches do not induce potent CD8 T-cell responses for fighting mostly variable viral diseases such as influenza, avian influenza viruses or HIV. Following our recent study on vaccine penetration by targeting of vaccine to human hair follicular ducts surrounded by Langerhans cells, we tested in the first randomized Phase-Ia trial based on hair follicle penetration (namely transcutaneous route) the induction of virus-specific CD8 T cell responses. Methods and Findings: We chose the inactivated influenza vaccine – a conventional licensed tetanus/influenza (TETAGRIP®) vaccine – to compare the safety and immunogenicity of transcutaneous (TC) versus IM immunization in two randomized controlled, multi-center Phase I trials including 24 healthy-volunteers and 12 HIV-infected patients. Vaccination was performed by application of inactivated influenza vaccine according to a standard protocol allowing the opening of the hair duct for the TC route or needle-injection for the IM route. We demonstrated that the safety of the two routes was similar. We showed the superiority of TC application, but not the IM route, to induce a significant increase in influenza-specific CD8 cytokine-producing cells in healthy-volunteers and in HIV-infected patients. However, these routes did not differ significantly for the induction of influenza-specific CD4 responses, and neutralizing antibodies were induced only by the IM route. The CD8 cell response is thus the major immune response observed after TC vaccination. Conclusions: This Phase Ia clinical trial (Manon05) testing an anti-influenza vaccine demonstrated that vaccines designed for antibody induction by the IM route, generate vaccine-specific CD8 T cells when administered transcutaneously. These results underline the necessity of adapting vaccination strategies to control complex infectious diseases when CD8 cellular responses are crucial. Our work opens up a key area for the development of preventive and therapeutic vaccines for diseases in which CD8 cells play a crucial role

Characterization of inhibitory effects of NH 2 OH and its N-methyl derivatives on the O 2 -evolving complex of Photosystem II

Inorganic cofactors (Mn, Ca 2+ and Cl - ) are essential for oxidation of H 2 O to O 2 by Photosystem II. The Mn reductants NH 2 OH and its N-methyl derivatives have been employed as probes to further examine the interactions between these species and Mn at the active site of H 2 O oxidation. Results of these studies show that the size of a hydroxylamine derivative regulates its ability to inactivate O 2 evolution activity, and that this size-dependent inhibition behavior arises from the protein structure of Photosystem II. A set of anions (Cl - , F - and SO 4 2- ) is able to slow NH 2 OH and CH 3 NHOH inactivation of intact Photosystem II membranes by exerting a stabilizing influence on the extrinsic 23 and 17 kDa polypeptides. In contrast to this non-specific anion effect, only Cl - is capable of attenuating CH 3 NHOH and (CH 3 ) 2 NOH inhibition in salt-washed preparations lacking the 23 and 17 kDa polypeptides. However, Cl - fails to protect against NH 2 OH inhibition in salt-washed membranes. These results indicate that the attack by NH 2 OH and its N-methyl derivatives on Mn occurs at different sites in the O 2 -evolving complex. The small reductant NH 2 OH acts at a Cl - -insensitive site whereas the inhibitions by CH 3 NHOH and (CH 3 ) 2 NOH involve a site that is Cl - sensitive. These findings are consistent with earlier studies showing that the size of primary amines controls the Cl - sensitivity of their binding to Mn in the O 2 -evolving complex.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43537/1/11120_2004_Article_BF00046773.pd