2,128 research outputs found
Software process reflexivity and business performance: initial results from an empirical study
Commercial software development organisations routinely operate in dynamic environments, with various situational factors that affect the software development approach undergoing recurring change. We therefore suggest that process reflexivity - the ability to reflect upon the suitability of a software process for a given context and to adapt the process according to changing situational circumstances â is an important capability for software development organizations.. In support of this position we conducted an exploratory industrial study of software development in practice. An initial analysis of our data suggests that software process reflexivity may exercise a strong influence over business success. Further work is required to fully examine our data, however, initial findings indicate that software process reflexivity is worthy of greater attentio
Discovery of genes implicated in whirling disease infection and resistance in rainbow trout using genome-wide expression profiling
<p>Abstract</p> <p>Background</p> <p>Whirling disease, caused by the pathogen <it>Myxobolus cerebralis</it>, afflicts several salmonid species. Rainbow trout are particularly susceptible and may suffer high mortality rates. The disease is persistent and spreading in hatcheries and natural waters of several countries, including the U.S.A., and the economic losses attributed to whirling disease are substantial. In this study, genome-wide expression profiling using cDNA microarrays was conducted for resistant Hofer and susceptible Trout Lodge rainbow trout strains following pathogen exposure with the primary objective of identifying specific genes implicated in whirling disease resistance.</p> <p>Results</p> <p>Several genes were significantly up-regulated in skin following pathogen exposure for both the resistant and susceptible rainbow trout strains. For both strains, response to infection appears to be linked with the interferon system. Expression profiles for three genes identified with microarrays were confirmed with qRT-PCR. <it>Ubiquitin-like protein 1 </it>was up-regulated over 100 fold and <it>interferon regulating factor 1 </it>was up-regulated over 15 fold following pathogen exposure for both strains. Expression of <it>metallothionein B</it>, which has known roles in inflammation and immune response, was up-regulated over 5 fold in the resistant Hofer strain but was unchanged in the susceptible Trout Lodge strain following pathogen exposure.</p> <p>Conclusion</p> <p>The present study has provided an initial view into the genetic basis underlying immune response and resistance of rainbow trout to the whirling disease parasite. The identified genes have allowed us to gain insight into the molecular mechanisms implicated in salmonid immune response and resistance to whirling disease infection.</p
Relationships among Members of the Genus Myxobolus (Myxozoa: Bilvalvidae) Based on Small Subunit Ribosomal DNA Sequences
Sequences representing similar to 1,700 base pairs of the 18S rRNA gene from 10 different species in the genus Myxobulus were found to group them into 3 clusters that showed little correlation with spore morphology and size or host specificity, criteria currently used for both higher and lower taxonomic placements in the Myxozoa. Of the phenotypic criteria examined, tissue tropism was most correlated with the rRNA groupings observed. Spores of similar size and shape (Myxobolus cerebralis vs. Myxobolus squamalis) were distantly related in some instances, whereas spores with divergent morphology and size were some times found to be closely related (M. cerebralis and Myxobolus insidiosus). These initial investigations into the phylogenetic relationships of putative members of the genus Myxobolus clearly indicate the potential limitations of groupings based on size and morphological properties of the spores and host species infected. We propose that 18S rRNA gene sequences, combined with information on tissue tropism, host species infected, and developmental cycles in the fish and alternate host (when and if known) be given greater consideration in taxonomic placements of myxosporeans
A New Era of Morphological Investigations: Reviewing Methods for Comparative Anatomical Studies
The increased use of imaging technology in biological research has drastically altered morphological studies in recent decades and allowed for the preservation of important collection specimens alongside detailed visualization of bony and soft-tissue structures. Despite the benefits associated with these newer imaging techniques, there remains a need for more âtra- ditionalâmethods of morphological examination in many comparative studies. In this paper, we describe the costs and benefits of the various methods of visualizing, examining, and comparing morphological structures. There are significant differences not only in the costs associated with these different methods (monetary, time, equipment, and software), but also in the degree to which specimens are destroyed. We argue not for any one particular method over another in morphological studies, but instead suggest a combination of methods is useful not only for breadth of visualization, but also for the financial and time constraints often imposed on early-career research scientists
Habitat corridors facilitate genetic resilience irrespective of species dispersal abilities or population sizes
Corridors are frequently proposed to connect patches of habitat that have become isolated due to humanâmediated alterations to the landscape. While it is understood that corridors can facilitate dispersal between patches, it remains unknown whether corridors can mitigate the negative genetic effects for entire communities modified by habitat fragmentation. These negative genetic effects, which include reduced genetic diversity, limit the potential for populations to respond to selective agents such as disease epidemics and global climate change. We provide clear evidence from a forwardâtime, agentâbased model (ABM) that corridors can facilitate genetic resilience in fragmented habitats across a broad range of species dispersal abilities and population sizes. Our results demonstrate that even modest increases in corridor width decreased the genetic differentiation between patches and increased the genetic diversity and effective population size within patches. Furthermore, we document a tradeâoff between corridor quality and corridor design whereby populations connected by highâquality habitat (i.e., low corridor mortality) are more resilient to suboptimal corridor design (e.g., long and narrow corridors). The ABM also revealed that species interactions can play a greater role than corridor design in shaping the genetic responses of populations to corridors. These results demonstrate how corridors can provide longâterm conservation benefits that extend beyond targeted taxa and scale up to entire communities irrespective of species dispersal abilities or population sizes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111750/1/eva12255.pd
Designed Guanidinium-Rich Amphipathic Oligocarbonate Molecular Transporters Complex, Deliver and Release siRNA in Cells
The polyanionic nature of oligonucleotides and their enzymatic degradation present challenges for the use of siRNA in research and therapy; among the most notable of these is clinically relevant delivery into cells. To address this problem, we designed and synthesized the first members of a new class of guanidinium-rich amphipathic oligocarbonates that noncovalently complex, deliver, and release siRNA in cells, resulting in robust knockdown of target protein synthesis in vitro as determined using a dual-reporter system. The organocatalytic oligomerization used to synthesize these co-oligomers is step-economical and broadly tunable, affording an exceptionally quick strategy to explore chemical space for optimal siRNA delivery in varied applications. The speed and versatility of this approach and the biodegradability of the designed agents make this an attractive strategy for biological tool development, imaging, diagnostics, and therapeutic applications
The fitness consequences of inbreeding in natural populations and their implications for species conservation â a systematic map
Background: Threatened species often have small and isolated populations where mating among relatives can
result in inbreeding depression increasing extinction risk. Effective management is hampered by a lack of syntheses
summarising the magnitude of, and variation in inbreeding depression. Here we describe the nature and scope
of the literature examining phenotypic/fitness consequences of inbreeding, to provide a foundation for future
syntheses and management.
Methods: We searched the literature for articles documenting the impact of inbreeding in natural populations.
Article titles, abstracts and full-texts were assessed against a priori defined criteria, and information relating to study
design, quality and other factors that may influence inbreeding responses (e.g. population size) was extracted from
relevant articles.
Results: The searches identified 11457 articles, of which 614 were assessed as relevant and included in the systematic
map (corresponding to 703 distinct studies). Most studies (663) assessed within-population inbreeding resulting from
self-fertilisation or consanguineous pairings, while 118 studies assessed among-population inbreeding due to drift load.
Plants were the most studied taxon (469 studies) followed by insects (52 studies) and birds (43 studies). Most studies
investigated the effects of inbreeding on components of fitness (e.g. survival or fecundity; 648 studies) but measurements
were typically under laboratory/greenhouse conditions (486 studies). Observations were also often restricted to the first
inbred generation (607 studies) and studies frequently lacked contextual information (e.g. population size).
Conclusions: Our systematic map describes the scope and quality of the evidence describing the phenotypic
consequences of inbreeding. The map reveals substantial evidence relating to inbreeding responses exists,
but highlights information is still limited for some aspects, including the effects of multiple generations of
inbreeding. The systematic map allowed us to define several conservation-relevant questions, where sufficient
data exists to support systematic reviews, e.g. How do inbreeding responses vary with population size? However,
we found that such syntheses are likely to be constrained by incomplete reporting of critical contextual information.
Our systematic map employed the same rigorous literature assessment methods as systematic review, including a
novel survey of study quality and thus provides a robust foundation to guide future research and syntheses seeking to
inform conservation decision-making
Oligocarbonate Molecular Transporters: Oligomerization-Based Syntheses and Cell-Penetrating Studies
A new family of guanidinium-rich molecular transporters featuring a novel oligocarbonate backbone with 1,7-side chain spacing is described. Conjugates can be rapidly assembled irrespective of length in a one-step oligomerization strategy that can proceed with concomitant introduction of probes (or by analogy drugs). The new transporters exhibit excellent cellular entry as determined by flow cytometry and fluorescence microscopy, and the functionality of their drug delivery capabilities was confirmed by the delivery of the bioluminescent small molecule probe luciferin and turnover by its intracellular target enzyme
Three-dimensional simulation for fast forward flight of a calliope hummingbird
We present a computational study of flapping-wing aerodynamics of a calliope hummingbird (Selasphorus calliope) during fast forward flight. Three-dimensional wing kinematics were incorporated into the model by extracting time-dependent wing position from high-speed videos of the bird flying in a wind tunnel at 8.3âmâsâ1. The advance ratio, i.e. the ratio between flight speed and average wingtip speed, is around one. An immersed-boundary method was used to simulate flow around the wings and bird body. The result shows that both downstroke and upstroke in a wingbeat cycle produce significant thrust for the bird to overcome drag on the body, and such thrust production comes at price of negative lift induced during upstroke. This feature might be shared with bats, while being distinct from insects and other birds, including closely related swifts
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