Morphometric differentiation and gene flow in emerald shiners (Notropis atherinoides) from the lower Great Lakes and the Niagara River

Differences in habitat (e.g., water velocity, prey, and predator regimes) are a driving force causing adaptive divergence among fish populations. This study used geometric shape analysis to assess morphological differences among emerald shiner (Notropis atherinoides) populations inhabiting the Niagara River, Lake Erie, and Lake Ontario. It was expected that emerald shiners inhabiting the two lakes would have more robust bodies and smaller heads, while river emerald shiners were expected to display more fusiform bodies with larger heads. The results of this study indicate that emerald shiners from Lake Erie and the Niagara River had a more robust form on average than individuals from Lake Ontario. Specifically, emerald shiners collected from Lake Ontario displayed more streamlined bodies and larger heads than emerald shiners collected from Lake Erie and the Niagara River. In addition, this divergence in body shape has apparently occurred despite the lack of distinct genetic differentiation as measured with microsatellite variation. Our results suggest that differences in water velocity alone may not be responsible for phenotypic variation in body shape among these emerald shiner populations, and other factors such as differences in prey or predator regimes are likely involved.     

Mechanical and thermal properties of starch‐filled poly(D,L‐lactic acid)/poly(hydroxy ester ether) biodegradable blends

The mechanical, structural, and thermal properties of injection‐molded composites of granular cornstarch, poly(D ,L ‐lactic acid) (PDLLA), and poly(hydroxy ester ether) (PHEE) were investigated. These composites had high tensile strengths, ranging from 17 to 66 MPa, at starch loadings of 0–70 wt %. Scanning electron microscopy micrographs of fracture specimens revealed good adhesion between the starch granule and the polymer matrix, as evidenced by broken starch granules. The adhesion of the starch granules to the polymer matrix was the greatest when the matrix PDLLA/PHEE ratios ranged from zero to unity. At a PDLLA/PHEE ratio of less than unity, as the starch content increased in the composites, there was an increase in the tensile strength and modulus, with a concurrent decrease in elongation. The effects of starch on the mechanical properties of starch/PDLLA composites showed that as the starch content of the composite increased, the tensile strength and elongation to break decreased, whereas Young's modulus increased. In contrast, the tensile strength of starch/PHEE composites increased with increasing starch content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1775–1786, 2003     

Guest network co-continuity in interpenetrating polymer networks: A diffusion study

Interpenetrating networks have been prepared using poly(dimethylsiloxane) as the host network and polymethacrylic acid as the guest network, i.e. polymerised and crosslinked in the presence of the siloxane network. These networks were swollen to equilibrium in dilute aqueous potassium chloride solutions and used as membranes to separate a solution of potassium chloride from pure water. The concentration of potassium chloride either side of each membrane was monitored as a function of time by conductivity measurements. From these data, the diffusion coefficient of potassium chloride in the membranes was calculated as a function of polymethacrylic acid content for temperatures of 303, 318 and 333K. Values of the diffusion coefficient were between 3 x 10^?7cm²s^?1 and 19 x 10^?5 cm² s^?1. The activation energy of the diffusive process decreased linearly with the increase in water content of the networks.     

A small angle neutron scattering investigation of block copolymers of styrene and isoprene in the solid state

Block copolymers of styrene and isoprene have been synthesized using anionic initiation, the weight fraction range of styrene covered being 0.20–0.85. The solid state structure has been examined by electron microscopy and small angle neutron scattering, for two copolymers small angle X-ray scattering measurements have also been made. From the neutron scattering measurements it has been possible to determine the structural arrangement of the domains, the domain morphology and size, the mean square radius of the styrene block in the domain and the interfacial layer thickness. The results have been compared with theoretical models of domain structure and the general theoretical features seem to be confirmed.     

Burst fractures of the lumbar spine in frontal crashes

Background

In the United States, major compression and burst type fractures (>20% height loss) of the lumbar spine occur as a result of motor vehicle crashes, despite the improvements in restraint technologies. Lumbar burst fractures typically require an axial compressive load and have been known to occur during a non-horizontal crash event that involve high vertical components of loading. Recently these fracture patterns have also been observed in pure horizontal frontal crashes. This study sought to examine the contributing factors that would induce an axial compressive force to the lumbar spine in frontal motor vehicle crashes.

Methods

We searched the National Automotive Sampling System (NASS, 1993–2011) and Crash Injury Research and Engineering Network (CIREN, 1996–2012) databases to identify all patients with major compression lumbar spine (MCLS) fractures and then specifically examined those involved in frontal crashes. National trends were assessed based on weighted NASS estimates. Using a case–control study design, NASS and CIREN cases were utilized and a conditional logistic regression was performed to assess driver and vehicle characteristics. CIREN case studies and biomechanical data were used to illustrate the kinematics and define the mechanism of injury.

Results

During the study period 132 NASS cases involved major compression lumbar spine fractures for all crash directions. Nationally weighted, this accounted for 800 cases annually with 44% of these in horizontal frontal crashes. The proportion of frontal crashes resulting in MCLS fractures was 2.5 times greater in late model vehicles (since 2000) as compared to 1990s models. Belted occupants in frontal crashes had a 5 times greater odds of a MCLS fracture than those not belted, and an increase in age also greatly increased the odds. In CIREN, 19 cases were isolated as horizontal frontal crashes and 12 of these involved a major compression lumbar burst fracture primarily at L1. All were belted and almost all occurred in late model vehicles with belt pretensioners and buckets seats.

Conclusion

Major compression burst fractures of the lumbar spine in frontal crashes were induced via a dynamic axial force transmitted to the pelvis/buttocks into the seat cushion/pan involving belted occupants in late model vehicles with increasing age as a significant factor.     

Optical parametric chirped-pulse amplifier as an alternative to Ti:sapphire regenerative amplifiers

We demonstrated a high-pulse energy, femtosecond-pulse source based on optical parametric chirped-pulse amplification. We successfully amplified 1-microm broadband oscillator pulses to 31 mJ and recompressed them to 310-fs pulse duration, at a 10-Hz repetition rate. The gain in our system is 6 x 10(7), achieved by the single passing of only 40 mm of gain material pumped by a commercial Q-switched Nd:YAG laser. This relatively simple system replaces a more complex Ti:sapphire regenerative-amplifier-based chirped-pulse amplification system. Numerous features in design and performance of optical parametric chirped-pulse amplifiers make them a preferred alternative to regenerative amplifiers based on Ti:sapphire in the front end of high-peak-power lasers.     

40 years later: Is the Boulder model still alive?

In an effort to determine the current status of the Boulder model, as outlined at the original conference, questionnaires were sent to clinical psychology training program directors at 138 American Psychological Association approved doctoral programs and 96 terminal master's programs. Directors of 97.8% of the 90 doctoral programs and 74.1% of the 58 master's programs who responded stated that their programs follow the Boulder model. Furthermore, there appears to be considerable adherence to the propositions recommended at the conference and, also, commitment to the model in the future. (PsycINFO Database Record (c) 2010 APA, all rights reserved)