Two types of S phase precipitates in Al-Cu-Mg alloys

Transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) have been used to study S phase precipitation in an Al-4.2Cu-1.5Mg-0.6Mn-0.5Si (AA2024) and an Al-4.2Cu-1.5Mg-0.6Mn-0.08Si (AA2324) (wt-%) alloy. In DSC experiments on as solution treated samples two distinct exothermic peaks are observed in the range 250 to 350°C, whereas only one peak is observed in solution treated and subsequently stretched or cold worked samples. Samples heated to 270°C and 400°C at a rate of 10°C/min in the DSC have been studied by TEM. The selected area diffraction patterns show that S phase precipitates with the classic orientation relationship form during the lower temperature peak, and for the solution treated samples, the higher temperature peak is caused by the formation of a second type of S phase precipitates which have an orientation relationship that is rotated by ~4 degrees to the classic one. The effects of Si and cold work on the formation of second type of S precipitates have been discussed

Test, Control and Monitor System maintenance plan

The maintenance requirements for Test, Control, and Monitor System (TCMS) and the method for satisfying these requirements prior to First Need Date (FND) of the last TCMS set are described. The method for satisfying maintenance requirements following FND of the last TCMS set will be addressed by a revision to this plan. This maintenance plan serves as the basic planning document for maintenance of this equipment by the NASA Payloads Directorate (CM) and the Payload Ground Operations Contractor (PGOC) at KSC. The terms TCMS Operations and Maintenance (O&M), Payloads Logistics, TCMS Sustaining Engineering, Payload Communications, and Integrated Network Services refer to the appropriate NASA and PGOC organization. For the duration of their contract, the Core Electronic Contractor (CEC) will provide a Set Support Team (SST). One of the primary purposes of this team is to help NASA and PGOC operate and maintain TCMS. It is assumed that SST is an integral part of TCMS O&M. The purpose of this plan is to describe the maintenance concept for TCMS hardware and system software in order to facilitate activation, transition planning, and continuing operation. When software maintenance is mentioned in this plan, it refers to maintenance of TCMS system software

TCMS operations and maintenance philosophy

The purpose is to describe the basic philosophies of operating and maintaining the Test, Control, and Monitor System (TCMS) equipment. TCMS is a complex and sophisticated checkout system. Operations and maintenance processes developed to support it will be based upon current experience, but will be focused on the specific needs of TCMS in support of Space Station Freedom Program (SSFP) and related activities. An overview of the operations and maintenance goals and philosophies are presented. The assumptions, roles and responsibilities, concepts and interfaces for operation, on-line maintenance, off-line support, and Operations and Maintenance (O&M) personnel training on all TCMS equipment located at KSC are described

Age and environment affect constitutive immune function in Red Knots (Calidris canutus)

We studied subspecies, age and environmental effects on constitutive immune function (natural antibody and complement titres, haptoglobin activity and leukocyte concentrations) in Red Knots (Calidris canutus). We compared C. c. islandica and C. c. canutus in the Wadden Sea and found no difference in immune function between subspecies. However, C. c. canutus on their wintering grounds in Banc d’Arguin had higher natural antibody and lower complement levels than C. c. canutus or C. c. islandica in the Wadden Sea. This suggests that immune function is determined more by the surrounding environment than by subspecies. We also compared age classes in the Wadden Sea and found that first year birds had significantly lower natural antibody levels than adults, but that second year birds no longer differed from adults. Finally, we examined the interaction of age and environment in Banc d’Arguin. We found that first year birds (but not adults) in a low quality habitat had higher leukocyte concentrations than first year birds or adults in a high quality habitat. Differences in available resources and defence needs between environments, and differences among individuals differentially distributed between sites, are likely important contributors to the variation in immune function we report. Future studies, which examine these factors on wild birds, will be important for our understanding of how animals function in their natural environment.

Baseball\u27s Moral Hazard: Law, Economics, and the Designated Hitter Rule

No subject prompts greater disagreement among baseball fans than the designated hitter rule, which allows teams to designate a player to hit for the pitcher. The rule increases the number of hit batsmen, and some have suggested this effect is a result of moral hazard, which recognizes that persons insured against risk are more likely to engage in dangerous behavior. Because American League pitchers do not bat, they allegedly are not deterred by the full cost of making risky, inside pitches—namely, retribution during their next at bat. Using a law-and-economics approach, this Article concludes that the designated hitter rule creates some moral hazard, but finds that recent structural changes to the game have largely overshadowed this effect. Moreover, the benefits of the rule—including increased offense and attendance—likely outweigh its costs in the American League. This is not necessarily true in the National League, however, due to differences in fan preferences. Thus, the current hybrid system (in which the American League allows designated hitters while the National League does not) best effectuates these fan preferences, maximizing social welfare

Time Well Spent: An Economic Analysis of Daylight Saving Time Legislation

Several nations implemented daylight saving time legislation in the last century, including the United States. The United States briefly experimented with year-round daylight saving time twice—during World War II and the energy crises in the 1970s. Agency studies and congressional hearings from the 1970s show several benefits of year-round daylight saving time, along with potential disadvantages. These studies are dated, and much has changed in the last thirty years. While congressional efforts to extend daylight saving time in 2007 have again focused on the energy savings this legislation would produce, far more meaningful benefits have been largely ignored. This Article collects and analyzes modern research on daylight saving time, concluding that year-round daylight saving time would save hundreds of lives annually by decreasing motor vehicle and pedestrian fatalities. Furthermore, extra light in the evening hours reduces criminal activity and results in energy savings from decreased peak electricity demand. Finally, year-round daylight saving time would eliminate the negative effects caused by the current spring and fall time changes. These advantages significantly outweigh the potential costs of daylight saving during winter months. The time has come for Congress to enact year-round daylight saving time legislation-each year we wait costs hundreds of American lives and millions of dollars. Part I of this Article examines the history of daylight saving time, from its origins as satirical fodder to the debates of the present day. This history shows that the United States has had an inconsistent (and not always rational) experience with daylight saving time. The nation oscillated between periods of uniform time observance and local time observance. It has twice experimented with year-round daylight saving time. If nothing else, the current summer observance of daylight saving time in the United States constitutes a middle point between the extremes of the past. Part II of this Article examines empirical results, focusing in particular on studies and research from the United States\u27 1974 experiment with year-round daylight saving time during the energy crises. Agency studies and congressional hearings from the 1970s highlight several advantages and disadvantages of extended daylight saving. This portion of the Article also stresses that these dated studies should inform our analysis of the issue, but they should not dictate our conclusions-much has changed in the last thirty years. Finally, Part III examines current studies and research using cost-benefit analysis and argues that Congress should implement year-round daylight saving time. Studies show that year-round daylight saving time has several significant advantages, including a decrease in motor vehicle and pedestrian fatalities, energy savings from reduced peak electricity demands, and a potential decrease in crime. Additionally, year-round daylight saving time avoids negative effects caused by the current spring and fall time changes. Finally, year-round daylight saving time does not endanger school children, and its benefits outweigh other notable disadvantages. Thus, on balance, the benefits of extending daylight saving time dramatically outweigh its costs, and Congress should step up to adopt year-round daylight saving time legislation before hundreds of additional lives are sacrificed by those who seek nothing better than the status quo

On cloud ice induced absorption and polarisation effects in microwave limb sounding

Microwave limb sounding in the presence of ice clouds was studied by detailed simulations, where clouds and other atmospheric variables varied in three dimensions and the full polarisation state was considered. Scattering particles were assumed to be horizontally aligned oblate spheroids with a size distribution parameterized in terms of temperature and ice water content. A general finding was that particle absorption is significant for limb sounding, which is in contrast to the down-looking case, where it is usually insignificant. Another general finding was that single scattering can be assumed for cloud optical paths below about 0.1, which is thus an important threshold with respect to the complexity and accuracy of retrieval algorithms. The representation of particle sizes during the retrieval is also discussed. Concerning polarisation, specific findings were as follows: Firstly, no significant degree of circular polarisation was found for the considered particle type. Secondly, for the ±45° polarisation components, differences of up to 4 K in brightness temperature were found, but differences were much smaller when single scattering conditions applied. Thirdly, the vertically polarised component has the smallest cloud extinction. An important goal of the study was to derive recommendations for future limb sounding instruments, particularly concerning their polarisation setup. If ice water content is among the retrieval targets (and not just trace gas mixing ratios), then the simulations show that it should be best to observe any of the ±45° and circularly polarised components. These pairs of orthogonal components also make it easier to combine information measured from different positions and with different polarisations

Red Quasars and Quasar Evolution: the Case of BALQSO FIRST J155633.8+351758

We present the first near-IR spectroscopy of the z=1.5 radio-loud BALQSO FIRST J155633.8+351758. Both the Balmer decrement and the slope of the rest-frame UV-optical continuum independently suggest a modest amount of extinction along the line of sight to the BLR (E(B-V)~0.5 for SMC-type screen extinction at the QSO redshift). The implied gas column density along the line of sight is much less than is implied by the weak X-ray flux of the object, suggesting that either the BLR and BAL region have a low dust-to-gas ratio, or that the rest-frame optical light encounters significantly lower mean column density lines of sight than the X-ray emission. From the rest-frame UV-optical spectrum, we are able to constrain the stellar mass content of the system. Comparing the maximal stellar mass with the black hole mass estimated from the bolometric luminosity of the QSO, we find that the ratio of the black hole to stellar mass may be comparable to the Magorrian value, which would imply that the Magorrian relation is already in place at z=1.5. However, multiple factors favor a much larger black hole to stellar mass ratio. This would imply that if the Magorrian relation characterizes the late history of QSOs, and the situation observed for F1556+3517 is typical of the early evolutionary history of QSOs, central black hole masses develop more rapidly than bulge masses. [ABRIDGED]Comment: 23 pages, 4 embedded postscript figures; Accepted for publication in The Astronomical Journal, December 200

Planning and Control of Robotic Juggling and Catching Tasks

A new class of control algorithms—the “mirror algorithms”— gives rise to experimentally observed juggling and catching behavior in a planar robotic mechanism. The simplest of these algorithms (on which all the others are founded) is provably correct with respect to a simplified model of the robot and its environment. This article briefly reviews the physical setup and underlying mathematical theory. It discusses two significant extensions of the fundamental algorithm to juggling two objects and catching. We provide data from successful empirical verifi cations of these control strategies and briefly speculate on the larger implications for the field of robotics. For more information: Kod*La