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Information regarding site occupancy of fish that migrate long distances during nonspawning periods together with estimates of recruitment trends for individual populations can be informative for management, especially when individuals from different spawning populations intermix and are sampled or harvested together. Tendencies for individuals from different populations to preferentially occupy specific regions increases vulnerability to anthropogenic and natural disturbances. Using mixed stock analysis (MSA), we estimated population-specific occupancy of lake sturgeon (Acipenser fulvescens) in open-water and nearshore regions of Lake Michigan across a hierarchy of spatial scales. Open-water mixture composition differed between Lake Michigan’s eastern and western basins. Significant heterogeneity in habitat occupancy was also observed at microgeographic scales throughout open-water regions of Green Bay, indicating nonrandom occupancy to regions proximal to natal streams. Estimates of relative recruitment levels determined from MSA extensions indicated increasing recruitment trends for spawning populations associated with Wisconsin tributaries (Oconto–Peshtigo, Fox, and Menominee rivers). Our lake sturgeon results demonstrate the utility of genetic data for informing management efforts for spatially structured, highly migratory species. Similar analyses could prove beneficial for species with similar characteristics.

Fish population structure in previously glaciated regions is often influenced by natural colonization processes and human-mediated dispersal, including fish stocking. Endemic populations are of conservation interest because they may contain rare and unique genetic variation. While coregonines are native to certain Michigan inland lakes, some were stocked with fish from Great Lakes sources, calling into question the origin of extant populations. While most stocking targeted lake whitefish (Coregonus clupeaformis), cisco (C. artedi) were also stocked from the Great Lakes to inland waterbodies. We used population genetic data (microsatellite genotypes and mitochondrial (mt)DNA sequences), coalescent modeling, and approximate Bayesian computation to investigate the origins of 12 inland Michigan cisco populations. The spatial distribution of mtDNA haplotypes suggests Michigan is an introgression zone for two ancestral cisco lineages associated with separate glacial refugia. Low levels of genetic diversity and high levels of genetic divergence were observed for populations located well inland of the Great Lakes relative to populations occupying waterbodies near the Great Lakes. Estimates of recent Great Lakes gene flow ranged from 27 to 48% for populations near the Great Lakes shoreline but were substantially lower (under 8%) for populations further inland. Inland lakes with elevated recent gene flow estimates may have been recipients of stocked coregonine fry, including cisco. Low levels of genetic diversity paired with a high likelihood of endemism as indicated by strong genetic divergence and low Great Lakes population inputs suggest the analyzed cisco populations occupying southern Michigan kettle lakes are of elevated conservation interest.

Populations of stream organisms across trophic levels, including microbial taxa, are adapted to physical and biotic stream features, and are sentinels of geological and hydrological landscape processes and anthropogenic disturbance. Stream bacterial diversity and composition can have profound effects on resident and migratory species in Great Lakes tributaries. Study objectives were to characterize and compare the taxonomic composition and diversity of bacterial communities in 18 rivers of the Lake Michigan basin during April and June 2019 and to quantify associations with stream and watershed physical features and dominant landuse practices. River water was filtered, and genomic DNA was extracted from filtrate using antiseptic techniques. We performed high-throughput amplicon sequencing using the highly variable V4 region of the 16S rRNA gene to characterize microbial community composition and diversity. Effects of landscape-scale landuse, environmental variables and dispersal predictors (e.g., inter-stream distance) on community compositional differences were quantified. Greater than 90% of variation in bacterial relative abundance between rivers and time were attributed to 11 phyla representing 10,800 operational taxonomic units. Inter-stream geographic distance, stream hydrology, and variation in stream properties that were tied to patterns of watershed landuse were significantly associated with differences in bacterial community composition among streams at both sampling time periods. based on Bray-Curtis distances. Understanding how environmental characteristics and watershed-scale landuse influence lower trophic level stream communities such as bacteria will inform managers as biological indicators of ecosystem health, sources of disturbance, and current and future bottom-up trophic changes in coupled tributary-Great Lakes ecosystems.

Intraspecific variation in pathogen shedding impacts disease transmission dynamics; therefore, understanding the host factors associated with individual variation in pathogen shedding is key to controlling and preventing outbreaks. In this study, ileum and bursa of Fabricius tissues of wild-bred mallards (

Additive manufactured (AM) foams in the context of high-power laser–matter interaction have emerged as a topic of significant interest. Printed foam targets provide a highly controlled environment for laser interaction and permit a high degree of versatility in terms of average density, spatial structure, and materials. These features are of great value to a variety of applications, including inertial confinement fusion and generation of intense x-rays and gamma rays. This paper describes an approach to the design and fabrication of AM foams for laser–plasma interaction experiments, including the selection of cellular structure, optimization of mechanical properties using a finite element approach, and foam printing on dielectric and conducting substrates.

Geometric morphometrics provides a powerful means of evaluating differences in phenotypic traits among specimens. However, inferences of trait variability can be confounded when measurements are based on preserved samples. We evaluated effects of ethanol preservation on morphology over a 22-week time period for a Laurentian Great Lakes invasive fish, round goby (Neogobius melanostomus, Pallas 1814), using sets of 17 lateral and six dorsal landmarks. We tested whether ethanol preservation affected the magnitude of inter-population variation between individuals collected from lake and river habitats. Generalized least square regression determined that length did not significantly vary through the preservation time series for fish from either population, while mass decreased significantly. Body shape variation was summarized using principal component analysis, which revealed that most preservation-associated changes occurred in the first 14 days. The lateral shape experienced a large magnitude change during the first 24 h in ethanol then only minor changes for the remainder of the study. The dorsal shape began to revert to pre-preservation measurements about 14 days following preservation. Additionally, differences in shape were apparent between the two populations throughout the experiment; however, the magnitude of differences between populations varied depending on whether dorsal or lateral landmarks were considered. Our study demonstrates that tissue responses to ethanol preservation can be more complex than a simple loss of mass, resulting in difficult to predict consequences for geometric morphometric analyses, including variable responses depending on the anatomical region being analyzed.

The Lake Michigan brown trout (Salmo trutta) fishery is sustained by the stocking of five hatchery strains by four state natural resource agencies. In the absence of exhaustive marking programs, strain-specific measures of stocking success are lacking for brown trout in Lake Michigan. We used microsatellite-based genetic assignment testing and genetic stock identification (GSI) to determine the strain of 122 angler-caught brown trout from four northeastern Lake Michigan ports. We compared strain composition estimates for sportfishing harvest to expected proportions of each brown trout strain in Lake Michigan at the time of harvest using stocking records corrected for age-specific mortality rates. Reassignment rates of individuals from baseline strains averaged 92.1% (range: 84.1–98.0%). Assignment testing and GSI analyses consistently found Wild Rose strain brown trout represented approximately 89% of the northeastern Lake Michigan sportfishing harvest, while only comprising 43.8% of the expected stock. Of the Michigan angler harvest of Wild Rose strain brown trout, approximately half were estimated to have originated from Wisconsin hatcheries, demonstrating a propensity for lake-wide movements. Continued assessments will improve understanding of strain relative contributions to angler harvests that can direct future stocking efforts.

Native species that persist in urban environments may benefit from local adaptation to novel selection factors. We used double-digest restriction-side associated DNA (RAD) sequencing to evaluate shifts in genome-wide genetic diversity and investigate the presence of parallel evolution associated with urban-specific selection factors in wood frogs (Lithobates sylvaticus). Our replicated paired study design involved 12 individuals from each of 4 rural and urban populations to improve our confidence that detected signals of selection are indeed associated with urbanization. Genetic diversity measures were less for urban populations; however, the effect size was small, suggesting little biological consequence. Using an FST outlier approach, we identified 37 of 8344 genotyped single nucleotide polymorphisms with consistent evidence of directional selection across replicates. A genome-wide association study analysis detected modest support for an association between environment type and 12 of the 37 FST outlier loci. Discriminant analysis of principal components using the 37 FST outlier loci produced correct reassignment for 87.5% of rural samples and 93.8% of urban samples. Eighteen of the 37 FST outlier loci mapped to the American bullfrog (Rana [Lithobates] catesbeiana) genome, although none were in coding regions. This evidence of parallel evolution to urban environments provides a powerful example of the ability of urban landscapes to direct evolutionary processes.

Intraspecific variation in host infectiousness affects disease transmission dynamics in human, domestic animal, and many wildlife host-pathogen systems including avian influenza virus (AIV); therefore, identifying host factors related to host infectiousness is important for understanding, controlling, and preventing future outbreaks. Toward this goal, we used RNA-seq data collected from low pathogenicity avian influenza virus (LPAIV)-infected blue-winged teal (Spatula discors) to determine the association between host gene expression and intraspecific variation in cloacal viral shedding magnitude, the transmissible fraction of virus. We found that host genes were differentially expressed between LPAIV-infected and uninfected birds early in the infection, host genes were differentially expressed between shed level groups at one-, three-, and five-days post-infection, host gene expression was associated with LPAIV infection patterns over time, and genes of the innate immune system had a positive linear relationship with cloacal viral shedding. This study provides important insights into host gene expression patterns associated with intraspecific LPAIV shedding variation and can serve as a foundation for future studies focused on the identification of host factors that drive or permit the emergence of high viral shedding individuals.

Intraspecific variation in pathogen shedding impacts disease transmission dynamics; therefore, understanding the host factors associated with individual variation in pathogen shedding is key to controlling and preventing outbreaks. In this study, ileum and bursa of Fabricius tissues of mallards (Anas platyrhynchos) infected with low-pathogenic avian influenza (LPAIV) were evaluated at various post-infection time points to determine genetic host factors associated with intraspecific variation in viral shedding. By analyzing transcriptome sequencing data (RNA-seq), we found that LPAIV-infected mallards do not exhibit differential gene expression compared to uninfected birds, but that gene expression was associated with viral shedding quantity early in the infection. In both tissues, immune genes were mostly up-regulated in higher shedding birds and had significant positive relationships with viral shedding. In the ileum, host genes involved in viral cell entry were down-regulated in low shedders one day post-infection (DPI), and host genes promoting viral replication were up-regulated in high shedders on two DPI. Our findings indicate that viral shedding is a key factor for gene expression differences in LPAIV-infected mallards, and the genes identified in this study could be important for understanding the molecular mechanisms driving intraspecific variation in pathogen shedding.

Background Oncolytic viruses are becoming an integral part of immunological approaches to cancer treatment. Interleukin-2 (IL-2) is known to stimulate cytotoxic T-cells, and might therefore be a reasonable cargo to enhance the therapeutic effect of such viruses. However, IL-2 is also known to promote immunosuppressive regulatory T-cells (T-reg). We investigated the impact of virally expressed IL-2 on induction of regulatory T-cells. We further investigated the effect of virally expressed IL-2 on the therapeutic efficacy of influenza A H1 and H5 subtypes. Materials and Methods Survival of B16 melanoma xenograft bearing mice upon treatment with various oncolytic influenza viruses was examined. Effect of these viruses on PBMC gathered from 4 young healthy volunteers and murine and human melanoma cell lines was examined utilizing multiple flow cytometry protocols. Results Viral IL-2 expression did not alter viral growth and was stable up to multiple passages in cell cultures. In human PBMC viral expression of IL-2 did not enhance differentiation of T-cells into a regulatory phenotype. In a murine B16 xenograft model IL-2 expression significantly enhanced therapeutic effects of an H1 oncolytic influenza virus. Expressed within the background of H5 hemagglutinin, IL-2 did not lead to a significant enhancement of therapeutic efficacy. Interestingly, the empty influenza H5 subtype was significantly more potent in treating B16 xenograft tumors than the H1 subtype, regardless of IL-2 expression. In primary human PBMC models, the virus based on H1 hemagglutinin led to enhanced CD8 T-cell activation compared to H5. This effect was further enhanced by IL-2 expression, although all viruses led to significant activation. Surprisingly, viruses based on H1 hemagglutinin led to increased expression of the immune checkpoint PD-1. The virus based on H5 hemagglutinin did not lead to upregulation of PD-1, indicating a favorable balance between activation and exhaustion. Infection with the H5 based virus led to both enhanced apoptosis and immunogenic calreticulin exposure in human and murine melanoma cell lines compared to H1. Conclusions IL-2 does not promote T-regs, when expressed in a viral background. H1 viruses induced PD-1 more potently than H5 viruses. The choice of viral entry protein is more relevant for the therapeutic effect of the virus, than the expression of a T-cell stimulating cytokine such as IL-2. Efficacy of oncolytic viral treatment appears to depend more on viral growth than on virally expressed T-cell promoting cargo. Disclosure Information J. Kabiljo: None. I. Kuznetsova: None. J. Homola: None. S. Prodinger: None. J. Laengle: None. M. Sachet: None. A. Egorov: A. Employment (full or part-time); Modest; Vacthera Bio Tech GmbH. M. Bergmann: A. Employment (full or part-time); Modest; Vacthera Bio Tech GmbH.

The blue-winged teal (Spatula discors) is a recreationally and ecologically important dabbling duck species in North America. Transcriptomic data of this species can be used in public and animal health studies given its role as a natural reservoir host for avian influenza, which can be a zoonotic disease of high concern. Ileum and bursa of Fabricius tissues were sampled from six captive raised blue-winged teals, four of the six who were experimentally infected with low-pathogenic avian influenza virus H5N9. RNAseq data were generated from extracted total mRNA from each tissue and pooled to create a de novo assembly of the transcriptome using Trinity. A total of 571,105 transcripts were identified at 449,956 unique unigenes that have been functionally annotated. This transcriptome will be useful for future blue-winged teal gene expression research, especially in hypothesis driven differential expression studies to determine the driving forces of avian influenza host-pathogen interactions, spatial distribution, and transmission.

This study used analyses of the genetic structure of a non-game fish species, the mottled sculpin Cottus bairdii to hypothesize probable recolonization routes used by cottids and possibly other Laurentian Great Lakes fishes following glacial recession. Based on samples from 16 small streams in five major Lake Michigan, U.S.A., tributary basins, significant interpopulation differentiation was documented (overall FST = 0·235). Differentiation was complex, however, with unexpectedly high genetic similarity among basins as well as occasionally strong differentiation within basins, despite relatively close geographic proximity of populations. Genetic dissimilarities were identified between eastern and western populations within river basins, with similarities existing between eastern and western populations across basins. Given such patterns, recolonization is hypothesized to have occurred on three occasions from more than one glacial refugium, with a secondary vicariant event resulting from reduction in the water level of ancestral Lake Michigan. By studying the phylogeography of a small, non-game fish species, this study provides insight into recolonization dynamics of the region that could be difficult to infer from game species that are often broadly dispersed by humans.

Most studies that investigate biases in stream fish abundance estimators focus on salmonines, yet nongame species comprise a major portion of fish assemblages. We evaluated mark–recapture (the Lincoln–Petersen estimator with Chapman correction) and removal (constant capture probability and generalized removal estimators) methods for estimating abundance of Mottled Sculpin Cottus bairdii, and we tested whether assumptions of the abundance estimators (i.e., the population is closed during sampling; and marks are detected) were reasonable. Over 2-d periods, fish in eight streams were sampled by using backpack electrofishing in 90-m reaches (each divided into three 30-m subreaches) to assess movement. Removal abundance estimates were significantly lower than mark–recapture estimates. Moreover, removal estimates were 52% lower than the known number of marked individuals, likely because capture probability (q) was low and declined with subsequent sampling passes. Survival of fish held in cages was 100%;...

The expansion of shell disease is an emerging threat to the inshore lobster fisheries in the northeastern United States. The development of models to improve the efficiency and precision of existing monitoring programs is advocated as an important step in mitigating its harmful effects. The objective of this study is to construct a statistical model that could enhance the existing monitoring effort through (1) identification of potential disease-associated abiotic and biotic factors, and (2) estimation of spatial variation in disease prevalence in the lobster fishery. A delta-generalized additive modeling (GAM) approach was applied using bottom trawl survey data collected from 2001-2013 in Long Island Sound, a tidal estuary between New York and Connecticut states. Spatial distribution of shell disease prevalence was found to be strongly influenced by the interactive effects of latitude and longitude, possibly indicative of a geographic origin of shell disease. Bottom temperature, bottom salinity, and depth were also important factors affecting the spatial variability in shell disease prevalence. The delta-GAM projected high disease prevalence in non-surveyed locations. Additionally, a potential spatial discrepancy was found between modeled disease hotspots and survey-based gravity centers of disease prevalence. This study provides a modeling framework to enhance research, monitoring and management of emerging and continuing marine disease threats.

Natural rates of straying are difficult to quantify over large spatial scales using direct observations, particularly for long-lived fish species characterized by delayed sexual maturity and long interspawning intervals. Using multilocus microsatellite genotypes and likelihood-based statistical methods, we quantified rates of immigration and emigration for six genetically differentiated (mean F ST = 0.041) lake sturgeon Acipenser fulvescens populations in Lake Michigan based on adults (n = 437) captured in tributaries during the spawning season. Estimated rates of straying were high (mean = 0.105), asymmetrical, and highly variable across populations. We found no significant association between the total length (a surrogate measure of age) of individuals that strayed and those that did not. Linear distance between streams was more predictive of straying rates and F ST than least-cost distances estimated based on lakescape features (bathymetry and lake current patterns). Historical rates of gene f...

The ability of fishery managers to quickly and effectively answer stakeholder questions using the best available science is crucial for successful management. The 2009 capture of a potential world record brown trout ( Salmo trutta ) and the 2010 capture of a potential world record land-locked Atlantic salmon ( S. salar ) in Michigan required managers to acquire genetic verification of the species identity. Given the variety of hatchery strains used to maintain Great Lakes fisheries for brown trout and in the absence of physical markings, managers also were interested to determine the strain of origin for information on assessing performance. DNA barcoding techniques using sequences from the mitochondrial (mt) DNA cytochrome c oxidase I (COI) gene and frequency-based analysis of species-specific microsatellite genotypes provided data to establish the species of both fish. The putative brown trout was confirmed to be a new world record specimen. Using individual assignment tests based on maximum likelihood estimators informed by multi-locus microsatellite genotypes, we determined the fish to be from the Seeforellen hatchery strain (p

Mortality that occurs during larval dispersal as a consequence of environmental, maternal, and genetic effects and their interactions can affect annual recruitment in fish populations. We studied larval lake sturgeon (Acipenser fulvescens) drift for two consecutive nights to examine whether larvae from different females exposed to the same environmental conditions during dispersal differed in relative levels of mortality. We estimated proportional contributions of females to larval collections and relative larval loss among females as larvae dispersed downstream between two sampling sites based on genetically determined parentage. Larval collections were composed of unequal proportions of offspring from different females that spawned at upstream and downstream locations (~0.8 km apart). Hourly dispersal patterns of larvae produced from females spawning at both locations were similar, with the largest number of larvae observed during 22:00–23:00 h. Estimated relative larval loss did not differ significantly among females as larvae were sampled at two sites approximately 0.15 and 1.5 km from the last section downstream of spawning locations. High inter- and intra-female variation in larval contributions and relative larval loss between nights may be a common feature of lake sturgeon and other migratory fish species, and likely is a source of inter-annual and intra-annual variation in fish recruitment.

Natal philopatry in lake sturgeon (Acipenser fulvescens) has been hypothesized to be an important factor that has lead to genetically distinct Great Lakes populations. Due to declining abundance, population extirpation, and restricted distribution, hatchery supplementation is being used to augment natural recruitment and to reestablish populations. If hatchery-reared lake sturgeon are more likely to stray than naturally produced individuals, as documented in other well-studied species, outbreeding could potentially jeopardize beneficial site-specific phenotypic and genotypic adaptations. From 1983 to 1994, lake sturgeon propagated using eggs taken from Lake Winnebago adults (Lake Michigan basin) were released in the St. Louis River estuary in western Lake Superior. Our objective was to determine whether these introduced individuals have strayed into annual spawning runs in the Sturgeon River, Michigan. Additionally, we estimated a natural migration rate between the Sturgeon River and Bad River, W...

The finite element method based on the full-vectorial H-field formulation incorporating the perturbation techniques has been employed to calculate the complex propagation characteristics, the formation of the coupled supermodes, and power fraction in the different regions, modal loss, differential loss and coupling length. The influence of the outer medium refractive index on the inner and outer surface plasmon modes (SPR) is investigated to achieve the best coupling and sensitivity. Finally the SRP fibre optic sensor design is numerically optimised for the maximum field penetration in the outer medium

This study used analyses of the genetic structure of a non-game fish species, the mottled sculpin Cottus bairdii to hypothesize probable recolonization routes used by cottids and possibly other Laurentian Great Lakes fishes following glacial recession. Based on samples from 16 small streams in five major Lake Michigan, U.S.A., tributary basins, significant interpopulation differentiation was documented (overall F

There are two primary factors limiting the commercial success of photochromic (PC) plastics, the relatively short lifetime of the finished products and their high cost. We attempted to produce a PC...

The static and dynamic parameters of a bipolar power diode are optimized by the use of helium irradiation. The optimal position for the defect peak caused by the irradiation was found in the n-base very close to the anode junction. This was verified by both the simulation and the experiment.

Transformation initiatives in the Department of Defense have major implications on the development of command and control structures in the joint environment. Alternative methodology will be required to rupture outdated tactics, techniques, and procedures established under legacy systems and organizational architectures. Taking into account newly developed concepts, such as the Air Component Coordination Element (ACCE), future command and control systems must build on lessons learned and continue to seek improvements for critical mission taskings. Lessons learned in Operations ENDURING FREEDOM and IRAQI FREEDOM indicate close air support remains a controversial topic due to the availability of air assets and fratricide. Since command and control of close air support is tied to the authority of the Joint Air Operations Center (JAOC) in joint doctrine, the responsibility lies with the JAOC to ensure senior ground elements are supported according to the Joint Force Commander s priorities. Establishing a modular Joint Air Component Coordination Element (JACCE) in the command and control architecture with expanded authorities will in due course eliminate deficiencies and enhance the interconnectivity of the functional land component commander with the functional air component commander.

Cellulose is one of the hemostyptic biomaterials, which are able to initiate or accelerate blood coagulation at the site of their application. It belongs to surgical sealants. The mechanism of its action is not clearly understood. We studied the participation of blood platelets in this mechanism. As a marker of platelet activation we used serotonin release reaction. Serotonin release in platelet rich plasma incubated with various concentrations of oxidized cellulose (0.5%-2.0%) started in about 20 min. Washed platelets were not directly activated by oxidized cellulose within one hour. Washed platelets reconstituted in plasma obtained from two patients with coagulation factor XII deficiency were activated by oxidized cellulose with a prolonged lag phase. Our results demonstrate the significant influence of factor XII on blood platelets activation by oxidized cellulose.

In a group of 7,721 foetuses with a high or low risk of cardiovascular pathology of the foetus, examined by complete foetal echocardiography, the authors found hyperechogenic ventricular structures in 211 foetuses (2.73% of the group) with a dominating localization in the left ventricle (97%). These structures are in the great majority a benign development variant which involves no risk for the development of the foetus. Rare localization beyond the left ventricle were not risk for the development of the foetus. Rare localization beyond the left ventricle were not associated with cardiac or other foetal pathologies. Echogenic ventricular focuses were not visualized by transvaginal echocardiography in the 13th week of pregnancy, although they were revealed in the same patient during the 21st week. Their presence does not affect left ventricular function and the function of the mitral valve pre-or postnatally. In the differential diagnosis these structures must be always differentiated from thrombi or cardiac tumours.

While most people, including this author, hold quite optimistic views of the photochromic industry, very little commercial success has been realized. In Professor Giacomo Ciamician's famous paper on photochemistry of the future, he predicted that photochromic clothing would be popular. It turns out that he was right. His paper was written in 1912 and photochromic clothing was not commercially successful under the early 1990's. These optimistic projections are commonplace. Unfortunately, the commercial successes have not been rapid or frequent. This paper is intended to address some of the critical success factors in achieving photochromic related profitability. The major ingredients of commercial success are an attractive industry and mastery of the specific critical business elements that lead to profitability in that industry.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The authors report normal values of one-dimensional echocardiography of the ventricles of foetuses obtained by analysis of high-standard 105 M-mode records of physiological foetuses aged 18-38 weeks. They assume their practical application by gynaecologists and child cardiologists during ultrasonographic screening of foetal pathology of the cardiovascular system.

Prevalence of congenital heart diseases was studied prospectively in all 664,218 infants live born in Bohemia from 1977 to 1984. All children who died were autopsied and those suspected of having a heart disease were examined at the specialized center. In total, 664/100,000 infants were born with a heart defect, most of them in Prague (957,9/100,000) and in Central Bohemia (739.4) and in Northern Bohemia (619.3). The lowest prevalence was found in West Bohemia (515.1/100000 live births). The relative frequency of congenital heart defect categories differed significantly among regions. Evidence of regional differences in prevalence of congenital heart diseases and their forms suggests that environmental factors can play an important role in the etiology of congenital heart defects.

The blocking state of a field-controlled thyristor (FCT) and the turn-off processes are discussed in relation to the design parameters of the structure. This leads to suggestions for a modified inner structure and a gate structure that should allow improved high power capability. Also considered is the integration of an FCT and a JFET to provide a device that is normally in the OFF state and that can be turned on and off by short low-power gate pulses.

The density and arrangement of dislocations is observed in deformed Cd single crystals by etch pitting. The density versus shear strain curves are given. These curves for crystals oriented for single slip differ from those oriented for double slip. Primary basal screw dislocations seem to prevail in crystals being deformed. For interpretation of the possible interaction of basal dislocations with different 〈1120〉 Burgers vectors is taken in account. The plastic behaviour of other h.c.p. metals as revealed by transmission electron microscopy is compared on the basis of the elastic interaction between dislocations with Burger's vector in the (0001) slip plane.