Performance evaluation of damper control settings for operation of multiple-zone variable air volume reheat system in different building applications and climate types

Choosing the right control strategies is an important task for effective operation of variable air volume reheat (VAVR) system in commercial buildings. In this design, dampers’ position inside air terminal units (ATUs) are modulated to adjust the amount of air supply volume based on thermal zones’ cooling or heating demand. A minimum air flow fraction (MAFF) is set for damper settings of ATUs to avoid under-ventilation problem in thermal zones. This study investigated the impact of MAFF value on various performance aspects of multiple-zone VAVR design in different building applications and climate types. A five-storey commercial building for three applications of school, office and retail in four climate types of tropical monsoon, hot desert, Mediterranean and humid continental have been simulated in EnergyPlus building simulation software. The results of simulations have shown that lowering MAFF value in ATUs would reduce the required reheat coil energy to maintain precise air supply temperature at part load cooling scenarios. Nonetheless, this reduction could have some implications on thermal comfort and indoor air quality level of thermal zones in a multiple-zone arrangement. It was concluded that in general it is an energy efficient control strategy to keep MAFF value to as low as 0.1 for high ventilation rate spaces like classrooms in school buildings (except for hot desert climate). On the other hand, it is advisable to not reduce MAFF value below 0.3 for low ventilation rate spaces like office areas to avoid any air quality issues in thermal zones

CEACAM1 Negatively Regulates IL-1β Production in LPS Activated Neutrophils by Recruiting SHP-1 to a SYK-TLR4-CEACAM1 Complex

LPS-activated neutrophils secrete IL-1β by activation of TLR-4. Based on studies in macrophages, it is likely that ROS and lysosomal destabilization regulated by Syk activation may also be involved. Since neutrophils have abundant expression of the ITIM-containing co-receptor CEACAM1 and Gram-negative bacteria such as Neisseria utilize CEACAM1 as a receptor that inhibits inflammation, we hypothesized that the overall production of IL-1β in LPS treated neutrophils may be negatively regulated by CEACAM1. We found that LPS treated neutrophils induced phosphorylation of Syk resulting in the formation of a complex including TLR4, p-Syk, and p-CEACAM1, which in turn, recruited the inhibitory phosphatase SHP-1. LPS treatment leads to ROS production, lysosomal damage, caspase-1 activation and IL-1β secretion in neutrophils. The absence of this regulation in Ceacam1−/− neutrophils led to hyper production of IL-1β in response to LPS. The hyper production of IL-1β was abrogated by in vivo reconstitution of wild type but not ITIM-mutated CEACAM1 bone marrow stem cells. Blocking Syk activation by kinase inhibitors or RNAi reduced Syk phosphorylation, lysosomal destabilization, ROS production, and caspase-1 activation in Ceacam1−/− neutrophils. We conclude that LPS treatment of neutrophils triggers formation of a complex of TLR4 with pSyk and pCEACAM1, which upon recruitment of SHP-1 to the ITIMs of pCEACAM1, inhibits IL-1β production by the inflammasome. Thus, CEACAM1 fine-tunes IL-1β production in LPS treated neutrophils, explaining why the additional utilization of CEACAM1 as a pathogen receptor would further inhibit inflammation

Genome-Wide Analysis of Heteroduplex DNA in Mismatch Repair–Deficient Yeast Cells Reveals Novel Properties of Meiotic Recombination Pathways

Meiotic DNA double-strand breaks (DSBs) initiate crossover (CO) recombination, which is necessary for accurate chromosome segregation, but DSBs may also repair as non-crossovers (NCOs). Multiple recombination pathways with specific intermediates are expected to lead to COs and NCOs. We revisited the mechanisms of meiotic DSB repair and the regulation of CO formation, by conducting a genome-wide analysis of strand-transfer intermediates associated with recombination events. We performed this analysis in a SK1 × S288C Saccharomyces cerevisiae hybrid lacking the mismatch repair (MMR) protein Msh2, to allow efficient detection of heteroduplex DNAs (hDNAs). First, we observed that the anti-recombinogenic activity of MMR is responsible for a 20% drop in CO number, suggesting that in MMR–proficient cells some DSBs are repaired using the sister chromatid as a template when polymorphisms are present. Second, we observed that a large fraction of NCOs were associated with trans–hDNA tracts constrained to a single chromatid. This unexpected finding is compatible with dissolution of double Holliday junctions (dHJs) during repair, and it suggests the existence of a novel control point for CO formation at the level of the dHJ intermediate, in addition to the previously described control point before the dHJ formation step. Finally, we observed that COs are associated with complex hDNA patterns, confirming that the canonical double-strand break repair model is not sufficient to explain the formation of most COs. We propose that multiple factors contribute to the complexity of recombination intermediates. These factors include repair of nicks and double-stranded gaps, template switches between non-sister and sister chromatids, and HJ branch migration. Finally, the good correlation between the strand transfer properties observed in the absence of and in the presence of Msh2 suggests that the intermediates detected in the absence of Msh2 reflect normal intermediates

Accurate Thermal Analysis Considering Nonlinear Thermal Conductivity

The increase in packing density has led to a higher power density in the chip which in turn has led to an increase in temperature on the chip. Temperature affects reliability, performance and power directly, motivating the need to accurately simulate the thermal profile of a chip. In literature, thermal conductivity is assumed to be a constant in order to obtain a linear system of equations which can be solved efficiently. But thermal conductivity is a nonlinear function of temperature and for silicon it varies by 22 % over the range 27 − 80 ◦ C[1]. If the nonlinearity of the thermal conductivity is ignored the thermal profile might be off by 10 ◦ C. Thus to get an accurate thermal profile it is important to consider the nonlinear dependence of the thermal conductivity on temperature. In this paper the nonlinear system arising out of considering the nonlinear thermal conductivity is solved efficiently using a variant of Newton-Raphson. In this paper we also study the abstraction levels under which the approximation of a periodic source by a DC source is valid. 1

An accurate sparse matrix based framework for statistical static timing analysis

Statistical Static Timing Analysis has received wide attention recently and emerged as a viable technique for manufacturability analysis. To be useful, however, it is important that the error introduced in SSTA be significantly smaller than the manufacturing variations being modeled. Achieving such accuracy requires careful attention to the delay models and to the algorithms applied. In this paper, we propose a new sparse-matrix based framework for accurate path-based SSTA, motivated by the observation that the number of timing paths in practice is sub-quadratic based on a study of industrial circuits and the ISCAS89 benchmarks. Our sparse-matrix based formulation has the following advantages: (a) It places no restrictions on process parameter distributions; (b) It embeds accurate polynomial-based delay model which takes into account slope propagation naturally; (c) It takes advantage of the matrix sparsity and high performance linear algebra for efficient implementation. Our experimental results are very promising. 1