Heatshield material selection for advanced ballistic reentry vehicles

The Performance of staple rayon fiber and AVTEX continuous rayon fiber was evaluated as precursor materials for heatshields. The materials studied were referenced to the IRC FM5055A heatshield materials flown during the past decade. Three different arc jet facilities were used to simulate portions of the reentry environment. The IRC FM5055A and the AVTEX FM5055G, both continuous rayon fiber woven materials having the phenolic impregnant filled with carbon particles were compared. The AVTEX continuous fiber, unfilled material FM5822A was also examined to a limited extent. Test results show that the AVTEX FM5055G material provided a close substitute for the IRC FM5055A material both in terms of thermal protection and roll torque performance

Consequences of Transport Low-Carbon Transitions and the Carbon, Land and Water Footprints of Different Fuel Options in The Netherlands

Transport greenhouse gas emissions are mainly caused by the use of fossil fuels, e.g., gasoline and diesel. This case study for the Netherlands calculates how alternative fuels, e.g., electricity, hydrogen or biofuels, contribute to policy aims to decarbonize transport. Alternative fuels, produced in various ways, have different carbon (CF), land (LFs) and water footprints (WFs). This study assesses CFs, LFs and WFs for fuels (kgCO2e/m2/m3 per GJ), showing differences among fuels dependent on primary energy sources. It calculates CFs, LFs and WFs for four scenarios with different fuels. The biofuel scenario is not attractive. CFs slightly decrease, while LFs and WFs increase enormously. The electricity scenario has small CFs and the smallest LFs and WFs, but this is only when using wind or solar energy. If storage is needed and hydrogen is produced using wind energy, CFs double from 3055 to 7074 kg CO2e, LFs increase from 15 106 to 43 106 m2 and WFs from 3 106 to 37 106 m3 compared to the electricity scenario. The case study shows that wise fuel choices contribute to policy aims to decarbonize transport, although LFs and WFs are also important to consider. These case study results are relevant for sustainable transportation transitions worldwide

Traumatic and Overuse Injuries of the Elbow

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145344/1/cpmia2701.pd

The law of demand in tiebout economies

We consider a general equilibrium local public goods economy in which agents have two distinguishing characteristics. The first is 'crowding type', which is publicly observable and provides direct costs or benefits to the jurisdiction (coalition or firms) the agent joins. The second is taste type, which is not publicly observable, has no direct effects on others and is defined over private good, public goods and the crowding profile of the jurisdiction the agent joins. The law of demand suggests that as the quantity of a given crowding type (plummers, lawers, smart people, tall people, nonsmokers, for example) increases, the compensation that agents of that type receive should go down. We provide counterexamples, however, that show that some agents of a given crowding type might actually benefit when the proportion of agents with the same crowding type increases. This reversal of the law of demand seems to have to do with interaction effect between tastes and skills, something difficult to study without making these classes of characteristics distinct. We argue that this reversal seems to relate to the degree of difference between various patterns of tastes. In particular, if tastes are homogeneous, the law of demand holds

Regulation of major histocompatibility complex class II gene expression in trophoblast cells

Trophoblast cells are unique because they are one of the few mammalian cell types that do not express major histocompatibility complex (MHC) class II antigens, either constitutively or after exposure to IFN-γ. The absence of MHC class II antigen expression on trophoblast cells has been postulated to be one of the essential mechanisms by which the semi-allogeneic fetus evades immune rejection reactions by the maternal immune system. Consistent with this hypothesis, trophoblast cells from the placentas of women suffering from chronic inflammation of unknown etiology and spontaneous recurrent miscarriages have been reported to aberrantly express MHC class II antigens. The lack of MHC class II antigen expression on trophoblast cells is due to silencing of expression of the class II transactivator (CIITA), a transacting factor that is essential for constitutive and IFN-γ-inducible MHC class II gene transcription. Transfection of trophoblast cells with CIITA expression vectors activates both MHC class II and class Ia antigen expression, which confers on trophoblast cells both the ability to activate helper T cells, and sensitivity to lysis by cytotoxic T lymphocytes. Collectively, these studies strongly suggest that stringent silencing of CIITA (and therefore MHC class II) gene expression in trophoblast cells is critical for the prevention of immune rejection responses against the fetus by the maternal immune system. The focus of this review is to summarize studies examining the novel mechanisms by which CIITA is silenced in trophoblast cells. The elucidation of the silencing of CIITA in trophoblast cells may shed light on how the semi-allogeneic fetus evades immune rejection by the maternal immune system during pregnancy

Evolution & voting: how nature makes us public spirited

We reconsider the classic puzzle of why election turnouts are persistently so high when formal analysis strongly suggests that rational agents should not vote. If we assume that voters are not making systematic mistakes,the most plausible explanation seems to be agents receive benefits, from the act of voting itself. This is very close to assuming the answer, however, and immediately begs the question of why agents feel a warm glow from participating in the electoral process. In this paper, we approach this question from an evolutionary standpoint. We show for a range of situations that public-spirited agents have an evolutionary advantage over those who are not as public-spirited. We also explore when this kind of altruistic behavior is disadvantageous to agents. The details depend on the costs of voting, the degree to which agents have different preferences over public policies and the ratio of various preference types in the population, but we conclude that evolution may often be a force that causes agents to internalize the benefits their actions confer on other

US 41 Crack & Seat Case Study A Practical Design

Crack and seat is one of the most cost-effective pavement rehabilitation techniques for existing old concrete with major distresses such as D cracking and joint failures. Using the MEPDG, INDOT saved $20 million from its proposed$33 million budget for this project