Bridge Deck Expansion Assembly on I-380 in Waterloo, HR-505B, 1990

The objective of this research was to evaluate two experimental Acme MSB neoprene expansion assemblies to identify possible construction problems and to determine the long term performance. These joints were installed in Black Hawk County on the curved bridge of ramp H from US 218 to I-380 in Waterloo, Iowa. Visual inspections were made yearly. There is slow leakage at one joint and indication that there is some slow leakage of both joints. The joint assemblies have performed well.

Bridge Deck Expansion Assembly on U.S. 20 in Sioux City, HR-505A, 1990

This project was to determine possible construction problems and evaluate the performance of experimental joint seals. Joints were installed in Woodbury County on US 20 over the Missouri River. ACME-Beta B-520 joints were used. Visual inspections were made yearly. Although the joints performed well for eight years, they deteriorated rapidly and have failed. It was concluded these joints did not perform satisfactorily.

Refinement of Rapid PCC Coarse Aggregate Testing Program, HR-1071, 1999

The characterization and categorization of coarse aggregates for use in portland cement concrete (PCC) pavements is a highly refined process at the Iowa Department of Transportation. Over the past 10 to 15 years, much effort has been directed at pursuing direct testing schemes to supplement or replace existing physical testing schemes. Direct testing refers to the process of directly measuring the chemical and mineralogical properties of an aggregate and then attempting to correlate those measured properties to historical performance information (i.e., field service record). This is in contrast to indirect measurement techniques, which generally attempt to extrapolate the performance of laboratory test specimens to expected field performance. The purpose of this research project was to investigate and refine the use of direct testing methods, such as X-ray analysis techniques and thermal analysis techniques, to categorize carbonate aggregates for use in portland cement concrete. The results of this study indicated that the general testing methods that are currently used to obtain data for estimating service life tend to be very reliable and have good to excellent repeatability. Several changes in the current techniques were recommended to enhance the long-term reliability of the carbonate database. These changes can be summarized as follows: (a) Limits that are more stringent need to be set on the maximum particle size in the samples subjected to testing. This should help to improve the reliability of all three of the test methods studied during this project. (b) X-ray diffraction testing needs to be refined to incorporate the use of an internal standard. This will help to minimize the influence of sample positioning errors and it will also allow for the calculation of the concentration of the various minerals present in the samples. (c) Thermal analysis data needs to be corrected for moisture content and clay content prior to calculating the carbonate content of the sample.

Rapid, simple and high yield production of recombinant proteins in mammalian cells using a versatile episomal system.

Many research projects in life sciences require purified biologically active recombinant protein. In addition, different formats of a given protein may be needed at different steps of experimental studies. Thus, the number of protein variants to be expressed and purified in short periods of time can expand very quickly. We have therefore developed a rapid and flexible expression system based on described episomal vector replication to generate semi-stable cell pools that secrete recombinant proteins. We cultured these pools in serum-containing medium to avoid time-consuming adaptation of cells to serum-free conditions, maintain cell viability and reuse the cultures for multiple rounds of protein production. As such, an efficient single step affinity process to purify recombinant proteins from serum-containing medium was optimized. Furthermore, a series of multi-cistronic vectors were designed to enable simultaneous expression of proteins and their biotinylation in vivo as well as fast selection of protein-expressing cell pools. Combining these improved procedures and innovative steps, exemplified with seven cytokines and cytokine receptors, we were able to produce biologically active recombinant endotoxin free protein at the milligram scale in 4-6weeks from molecular cloning to protein purification.

Effect of CA-Montmorillonite Expansion on X-Ray Diffraction Intensities, Progress Report, HR-111, 1966

The most abundant clay mineral group in Iowa soils is montmorillonite, most commonly calcium-saturated (Hanway et al, 1960). The calcium montmorillonite-water system was therefore selected for detailed X-ray study. Montmorillonite is unusual among minerals in that it has an expanding lattice in the c direction. That is, upon wetting with water, the individual silicate layers separate to allow entry of water, and the mineral expands. Characteristics of this expansion are readily studied by means of X-ray diffraction: the X-ray diffraction angle gives the average layer-to-layer "d001" spacing for any given moisture condition; the sharpness of the diffraction peak is a measure of uniformity of the d001 spacing; and the intensity of the peak relates to uniformity of the d001 spacing and in addition to the electron density distribution within the repeating elements. The latter is embodied in the "structure factor".

Tests diagnostiques rapides (TDR): la panacée pour le praticien [Rapid diagnostic tests (RDT): the cure-all for the practitioner?].

Many rapid diagnostic tests (RDT) for the diagnosis of infectious diseases have been developed over the last 20 years. These allow (1) administering a treatment immediately in case of a potentially fatal disease, (2) prescribing a specific rather than presumptive treatment, (3) quickly introducing measures aimed at interrupting the transmission of the disease, (4) avoiding useless antibiotic treatments and (5) implementing a sequential diagnostic strategy to avoid extensive investigations. Using the example of malaria, a new strategy that includes a RDT as first-line emergency diagnostic tool and, when negative, delayed microscopy at the laboratory opening time is implemented in Lausanne since 1999. This strategy has been shown to be safe. Each TDR has its own characteristics that imperatively need to be known by the practitioner if he/she wants to use it in a rational way.

Evaluation of Rapid Determination of the Chloride Permeability of Portland Cement Concrete by AASHTO T277-83, MLR-86-11, 1987

An Iowa D.O.T. Laboratory built machine was constructed for the chloride permeability testing of concrete by measuring electric current through a specimen between a salt solution and a base solution. This study had two purposes. The first was to evaluate the machine's performance. To do this, three concrete mixes were made consisting of different cement factors and water/cement ratios. Each mix was tested for chloride ion content by the 90- day salt ponding method and for chloride permeability at a 28-day cure by the permeability machine. The results from each test were evaluated to see if there was correlation between chloride ion content and the chloride permeability. It was determined that there was a correlation and that the permeability machine was satisfactory for determining chloride permeability in concrete. The second purpose of this study was to examine the effects that pozzolans have on the chloride permeability of concrete. Four mixes were made: one without any pozzolans as a control, one with class C fly ash, one with class F fly ash, and one with silica fume. Specimens from each mix were evaluated for chloride ion content by the 90-day salt ponding test and by the laboratory built machine for chloride permeability after curing 28 days. Specimens from these mixes were also taken from the salt ponding slabs after completion of the ponding test to examine the effect chloride ion content has on the operation of the chloride permeability machine. Specimens containing pozzolans were also examined for chloride permeability after a cure of 180 days. It was determined that the addition of pozzolans to concrete lowers the chloride permeability as measured by the permeability machine. Class F fly ash and silica fume in the concrete had a major effect in lowering the chloride permeability in concrete as measured by the permeability machine.

Problems of Bridge Supporting and Expansion Devices and an Experimental Comparison of the Dynamic Behavior of Rigid and Elastomeric Bearings, HR-105, 1965

The design of satisfactory supporting and expansion devices for highway bridges is a problem which has concerned bridge design engineers for many years. The problems associated with these devices have been emphasized by the large number of short span bridges required by the current expanded highway program of expressways and interstate highways. The initial objectives of this investigation were: (1) To review and make a field study of devices used for the support of bridge superstructures and for provision of floor expansion; (2) To analyze the forces or factors which influence the design and behavior of supporting devices and floor expansion systems; and (3) To ascertain the need for future research particularly on the problems of obtaining more economical and efficient supporting and expansion devices, and determining maximum allowable distance between such devices. The experimental portion was conducted to evaluate one of the possible simple and economical solutions to the problems observed in the initial portion. The investigation reported herein is divided into four major parts or phases as follows: (1) A review of literature; (2) A survey by questionnaire of design practice of a number of state highway departments and consulting firms; (3) Field observation of existing bridges; and, (4) An experimental comparison of the dynamic behavior of rigid and elastomeric bearings.

Rapid Biodiversity Assessment and Monitoring Method for Highly Diverse Benthic Communities: A Case Study of Mediterranean Coralligenous Outcrops

Increasing anthropogenic pressures urge enhanced knowledge and understanding of the current state of marine biodiversity. This baseline information is pivotal to explore present trends, detect future modifications and propose adequate management actions for marine ecosystems. Coralligenous outcrops are a highly diverse and structurally complex deep-water habitat faced with major threats in the Mediterranean Sea. Despite its ecological, aesthetic and economic value, coralligenous biodiversity patterns are still poorly understood. There is currently no single sampling method that has been demonstrated to be sufficiently representative to ensure adequate community assessment and monitoring in this habitat. Therefore, we propose a rapid non-destructive protocol for biodiversity assessment and monitoring of coralligenous outcrops providing good estimates of its structure and species composition, based on photographic sampling and the determination of presence/absence of macrobenthic species. We used an extensive photographic survey, covering several spatial scales (100s of m to 100s of km) within the NW Mediterranean and including 2 different coralligenous assemblages: Paramuricea clavata (PCA) and Corallium rubrum assemblage (CRA). This approach allowed us to determine the minimal sampling area for each assemblage (5000 cm² for PCA and 2500 cm²for CRA). In addition, we conclude that 3 replicates provide an optimal sampling effort in order to maximize the species number and to assess the main biodiversity patterns of studied assemblages in variability studies requiring replicates. We contend that the proposed sampling approach provides a valuable tool for management and conservation planning, monitoring and research programs focused on coralligenous outcrops, potentially also applicable in other benthic ecosystems

HIV rebounds from latently infected cells, rather than from continuing low-level replication.

Rapid rebound of plasma viremia in patients after interruption of long-term combination antiretroviral therapy (cART) suggests persistence of low-level replicating cells or rapid reactivation of latently infected cells. To further characterize rebounding virus, we performed extensive longitudinal clonal evolutionary studies of HIV env C2-V3-C3 regions and exploited the temporal relationships of rebounding plasma viruses with regard to pretreatment sequences in 20 chronically HIV-1-infected patients having undergone multiple 2-week structured treatment interruptions (STI). Rebounding virus during the short STI was homogeneous, suggesting mono- or oligoclonal origin during reactivation. No evidence for a temporal structure of rebounding virus in regard to pretreatment sequences was found. Furthermore, expansion of distinct lineages at different STI cycles emerged. Together, these findings imply stochastic reactivation of different clones from long-lived latently infected cells rather than expansion of viral populations replicating at low levels. After treatment was stopped, diversity increased steadily, but pretreatment diversity was, on average, achieved only >2.5 years after the start of STI when marked divergence from preexisting quasispecies also emerged. In summary, our results argue against persistence of ongoing low-level replication in patients on suppressive cART. Furthermore, a prolonged delay in restoration of pretreatment viral diversity after treatment interruption demonstrates a surprisingly sustained evolutionary bottleneck induced by punctuated antiretroviral therapy.

A new self-expanding aortic stent valve with annular fixation: in vitro haemodynamic assessment.

OBJECTIVE: Balloon-expandable stent valves require flow reduction during implantation (rapid pacing). The present study was designed to compare a self-expanding stent valve with annular fixation versus a balloon-expandable stent valve. METHODS: Implantation of a new self-expanding stent valve with annular fixation (Symetis, Lausanne, Switzerland) was assessed versus balloon-expandable stent valve, in a modified Dynatek Dalta pulse duplicator (sealed port access to the ventricle for transapical route simulation), interfaced with a computer for digital readout, carrying a 25 mm porcine aortic valve. The cardiovascular simulator was programmed to mimic an elderly woman with aortic stenosis: 120/85 mmHg aortic pressure, 60 strokes/min (66.5 ml), 35% systole (2.8 l/min). RESULTS: A total of 450 cardiac cycles was analysed. Stepwise expansion of the self-expanding stent valve with annular fixation (balloon-expandable stent valve) resulted in systolic ventricular increase from 120 to 121 mmHg (126 to 830+/-76 mmHg)*, and left ventricular outflow obstruction with mean transvalvular gradient of 11+/-1.5 mmHg (366+/-202 mmHg)*, systolic aortic pressure dropped distal to the valve from 121 to 64.5+/-2 mmHg (123 to 55+/-30 mmHg) N.S., and output collapsed to 1.9+/-0.06 l/min (0.71+/-0.37 l/min* (before complete obstruction)). No valve migration occurred in either group. (*=p<0.05). CONCLUSIONS: Implantation of this new self-expanding stent valve with annular fixation has little impact on haemodynamics and has the potential for working heart implantation in vivo. Flow reduction (rapid pacing) is not necessary.

Rapid genotypic change and plasticity in arbuscular mycorrhizal fungi is caused by a host shift and enhanced by segregation.

Arbuscular mycorrhizal fungi (AMF) are among the most abundant symbionts of plants, improving plant productivity and diversity. They are thought to mostly grow vegetatively, a trait assumed to limit adaptability. However, AMF can also harbor genetically different nuclei (nucleotypes). It has been shown that one AMF can produce genotypically novel offspring with proportions of different nucleotypes. We hypothesized that (1) AMF respond rapidly to a change of environment (plant host) through changes in the frequency of nucleotypes; (2) genotypically novel offspring exhibit different genetic responses to environmental change than the parent; and (3) genotypically novel offspring exhibit a wide range of phenotypic plasticity to a change of environment. We subjected AMF parents and offspring to a host shift. We observed rapid and large genotypic changes in all AMF lines that were not random. Genotypic and phenotypic responses were different among offspring and their parents. Even though growing vegetatively, AMF offspring display a broad range of genotypic and phenotypic changes in response to host shift. We conclude that AMF have the ability to rapidly produce variable progeny, increasing their probability to produce offspring with different fitness than their parents and, consequently, their potential adaptability to new environmental conditions. Such genotypic and phenotypic flexibility could be a fast alternative to sexual reproduction and is likely to be a key to the ecological success of AMF.

Residence time, expansion toward the equator in the invaded range and native range size matter to climatic niche shifts in non-native species

Aim Identifying climatic niche shifts and their drivers is important to accurately predict the risk of biological invasions. The niches of non-native plants and birds have recently been assessed in large-scale multi-species studies, but such large-scale tests are lacking for non-native reptiles and amphibians (herpetofauna). Furthermore, little is known about the factors contributing to niche shifts when they occur. Based on the occurrence of 71 reptile and amphibian species, we compared native and non-native realized niches in 101 invaded ranges at a worldwide scale and identified the factors that affect niche shifts. Location The world except the Antarctic. Methods We assessed climatic niche dynamics in a gridded environmental space allowing the quantification of niche overlap and expansion into climatic conditions not colonized by the species in their native range. We analyzed the factors affecting niche shifts using a model averaging approach based on generalized linear mixed-effects models. Results Approximately 57% of the invaded ranges (51% for amphibians and 61% for reptiles) showed niche shifts (≥10% expansion in the realized climatic niche). Island endemics, species introduced to Oceania and invaded ranges outside the native biogeographic realm showed a higher proportion of niche shifts. Niche shifts were more likely for species that had smaller native range sizes, were introduced earlier into a new range or invaded areas located at lower latitudes than the native range. Main conclusions The proportion of niche shifts for non-native herpetofauna was higher than those for Holarctic non-native plants and European non-native birds. The 'climate matching hypothesis' should be used with caution for species shifting their niche because it could underestimate the risk of their establishment.