Zoogeography of Iowa\u27s Paleozoic Plateau

The Paleozoic Plateau and adjacent rocky outcrop areas of northeastern Iowa harbor many of the state’s most unique animal species. Nearly 40% of the state\u27s endangered or threatened vertebrates and all of Iowa\u27s animals on the national list are known from this region. Quantitative comparisons with other parts of the state confirm the existence of a rich vertebrate fauna in the Paelozoic Plateau region. Its peripheral location within Iowa, extensive forest cover, and relatively undisturbed river systems account largely for the occurrence of species found rarely or not at all elsewhere in the state. Less mobile organisms such as land snails and other invertebrates have been influenced more directly by northeast Iowa\u27s peculiar geological history. The Paleozoic Plateau probably has served as both a glacial and post-glacial refugium for relict species. Recent studies suggest that the biological uniqueness of the region might not be fully realized

Nonisomorphic curves that become isomorphic over extensions of coprime degrees

We show that one can find two nonisomorphic curves over a field K that become isomorphic to one another over two finite extensions of K whose degrees over K are coprime to one another. More specifically, let K_0 be an arbitrary prime field and let r and s be integers greater than 1 that are coprime to one another. We show that one can find a finite extension K of K_0, a degree-r extension L of K, a degree-s extension M of K, and two curves C and D over K such that C and D become isomorphic to one another over L and over M, but not over any proper subextensions of L/K or M/K. We show that such C and D can never have genus 0, and that if K is finite, C and D can have genus 1 if and only if {r,s} = {2,3} and K is an odd-degree extension of F_3. On the other hand, when {r,s}={2,3} we show that genus-2 examples occur in every characteristic other than 3. Our detailed analysis of the case {r,s} = {2,3} shows that over every finite field K there exist nonisomorphic curves C and D that become isomorphic to one another over the quadratic and cubic extensions of K. Most of our proofs rely on Galois cohomology. Without using Galois cohomology, we show that two nonisomorphic genus-0 curves over an arbitrary field remain nonisomorphic over every odd-degree extension of the base field.Comment: LaTeX, 32 pages. Further references added to the discussion in Section 1

International Space Station United States Orbital Segment Oxygen Generation System On-Orbit Operational Experience

The International Space Station (ISS) United States Orbital Segment (USOS) Oxygen Generation System (OGS) was originally intended to be installed in ISS Node 3. The OGS rack delivery was accelerated, and it was launched to ISS in July of 2006 and installed in the US Laboratory Module. Various modification kits were installed to provide its interfaces, and the OGS was first activated in July of 2007 for 15 hours, In October of 2007 it was again activated for 76 hours with varied production rates and day/night cycling. Operational time in each instance was limited by the quantity of feedwater in a Payload Water Reservoir (PWR) bag. Feedwater will be provided by PWR bag until the USOS Water Recovery System (WRS) is delivered to SS in fall of 2008. This paper will discuss operating experience and characteristics of the OGS, as well as operational issues and their resolution

Integrity testing of brush seal in a T-700 engine

A split-ring brush seal was fabricated, installed between two labyrinth-honeycomb shroud seals, and tested in the fourth-stage turbine of a T-700 engine. The annealed Haynes 25 bristles rubbed directly against the nonconditioned, irregular Rene 80 turbine blade shroud surface. A total of 21 hr of cyclic and steady-state data were taken with surface speeds of 335 m/s (1100 ft/s) and shroud temperatures to 620 C (1150 F). Wear appeared to be rapid initially, with an orange flash of hot brush fragments during the first engine startup, to minimal after 10 hr of operation. The brush survived the testing but experienced some bristle pullouts and severe bristle wear; some turbine interface wear and possible material transfer was noted. Future design concerns center on tribological behavior at the interface with or without lubricants

Integrity testing of brush seal in shroud ring of T-700 engine

A split-ring brush seal was fabricated, installed between two labyrinth-honeycomb shroud seals, and tested in the fourth-stage turbine of a T-700 engine. The annealed Haynes 25 bristles rubbed directly against the nonconditioned, irregular Rene 80 turbine blade shroud surface. A total of 30 hr of cyclic and steady-state data were taken with surface speeds to 335 m/s (1100 ft/s) and shroud temperatures to 620 C (1150 F). Wear appeared to be rapid initially, with an orange flash of hot brush fragments during the first engine startup, to minimal after 10 hr of operation. The brush survived the testing but experienced some bristle pullouts and severe bristle wear; some turbine interface wear and possible material transfer was noted. Future design concerns center on tribological behavior at the interface with or without lubricants

Representativeness of observed couple interactions: Couples can tell, and it does make a difference

Research evidence suggests that people's public self-presentations may be biased in socially desirable directions. Using videotaped samples of couple interactions, this study examined the extent to which self-presentational bias occurs in such samples and the impact of such bias on the predictive validity of observed behavior. Each member of 239 couples rated the typicality of their partner's taped socially supportive and undermining behaviors. Separate multi-item, internally consistent measures of typicality of support and undermining were found. Analyses showed that these measures did not appear subject to bias and could identify subgroups that varied notably in the criterion validity of their observational data. These effects appeared for typicality of social support but not for typicality of social undermining. Partner ratings may be a promising tool for isolating invalid samples of observed behavior. One of the most challenging tasks in psychological research is the collection of valid observational data on people in normal social interactions. Such observations are usually interpreted as reflections of more general patterns of behavior because they occur in natural settings, and they are considered valid if they are such reflections. Scientists who conduct observational research, however, have long been aware that various characteristics of the research design can affect participants' behavior during such data collection. For example, Gottman (1979, p. 248) has found evidence that couples' behavior is more negative, with more negative affect reciprocity and less agreement, when assessed in the home rather than in a laboratory setting. A large body of evidence suggests that such effects may occur because people tend to bias their self-presentations of private behavior in socially desirable directions during public interac

Development of stable reporter system cloning luxCDABE genes into chromosome of Salmonella enterica serotypes using Tn7 transposon

<p>Abstract</p> <p>Background</p> <p>Salmonellosis may be a food safety problem when raw food products are mishandled and not fully cooked. In previous work, we developed bioluminescent <it>Salmonella enterica </it>serotypes using a plasmid-based reporting system that can be used for real-time monitoring of the pathogen's growth on food products in short term studies. In this study, we report the use of a Tn7-based transposon system for subcloning of <it>luxCDABE </it>genes into the chromosome of eleven <it>Salmonella enterica </it>serotypes isolated from the broiler production continuum.</p> <p>Results</p> <p>We found that the <it>lux </it>operon is constitutively expressed from the chromosome post-transposition and the <it>lux </it>cassette is stable without external pressure, i.e. antibiotic selection, for all <it>Salmonella enterica </it>serotypes used. Bioluminescence expression is based on an active electron transport chain and is directly related with metabolic activity. This relationship was quantified by measuring bioluminescence against a temperature gradient in aqueous solution using a luminometer. In addition, bioluminescent monitoring of two serotypes confirmed that our chicken skin model has the potential to be used to evaluate pathogen mitigation strategies.</p> <p>Conclusions</p> <p>This study demonstrated that our new stable reporting system eliminates bioluminescence variation due to plasmid instability and provides a reliable real-time experimental system to study application of preventive measures for <it>Salmonella </it>on food products in real-time for both short and long term studies.</p

Distribution and Abundance of Birds in the Loess Hills of Western Iowa

Recent investigations have provided a good understanding of the distribution and abundance of birds in the Loess Hills. Surveys have been conducted during natural history forays sponsored by the State Preserves Advisory Board and by our quantitative investigation during 1982-83. Fifteen stations covering the entire length of Iowa\u27s Loess Hills landform were visited. Three habitats were sampled at each station: native grassland, agricultural (brome or alfalfa) field, and forest. This paper describes typical bird communities of each habitat and compares species composition within and between stations. Grassland bird communities tend to be richer in the northern Loess Hills; the opposite is true for forest bird communities. Cultivated grasslands generally support a greater diversity of species than do native prairies. A notable exception occurs in Plymouth County, where extensive tracts of prairie are inhabited by a relatively diverse assemblage of grassland birds. We propose that small area, steepness of slope, and other factors render today\u27s prairie remnants poorly suited for grassland birds. The best quality grasslands in the Loess Hills probably occurred in lowlands or on gentle slopes, which today have been converted to agriculture. The richest diversities of birds in the Loess Hills occur in forests, a habitat type that was not extensive at the time of settlement