588 research outputs found
Estimation of Production Forgone
Three methods for estimating production forgone were compared by assessing the effects of power plant entrainment and impingement on gizzard shad Dorosoma cepedianum in western Lake Erie. The three approaches evaluated were (1) the Rago (1984) method, which is a direct method based on exponential mortality and growth, (2) a continuous‐time direct method based on exponential mortality and the von Bertalanffy growth equation, and (3) an indirect method, based on exponential mortality and the von Bertalanffy growth equation, in which production forgone was calculated as the difference between population production with and without an environmental disturbance. The indirect method gives a measure of the relative effect of the power plant‐induced mortality and production, but requires estimation of recruitment, which is difficult to estimate. An initial estimate of production forgone by the direct approach of Rago (1984), which does not require an estimate of recruitment, can be used to estimate recruitment for the indirect estimate of production forgone; together, the direct and indirect approaches give a more complete assessment of production forgone. A sensitivity analysis showed production forgone was sensitive to changes in mortality rates of larvae, young of the year, and juveniles and to change in the asymptotic weight of adults.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142154/1/nafm0191.pd
Morphological Identification of Parasites Found in Ducks (Family Anatidae) Along the Mississippi River: A Parasitology Class Project
Ducks (Anatidae) can be found across much of the United States and are hosts to a variety of parasites such as nematodes, trematodes or cestodes. This study focused on identifying the species of the parasites found within ducks based on their morphological features. The morphological structures consisted of body shape, internal organs, mouthparts, and length. The ducks used in this study were legally harvested and donated by hunters from areas across the Mississippi River in Buffalo County and Trempealeau County Wisconsin. A total of 108 ducks have been analyzed for parasites. It is important to identify the types of parasites that use ducks as a host, to see if they are harmful to the ducks so that they can be better managed. Necropsy was performed on different species of ducks to extract endo and ectoparasites. The extracted parasites were stained using carmine borax so they could be viewed using microscopy. While examining the parasites under the microscope, length and width measurements were taken as well as identifying key features like hold fast organs. A published key was used as a guide to identify parasites based on the measurements and key features present. The identified parasites were compared with DNA analysis from another research group to help ensure that the identification of the parasites was correct. Finally, identifications were compared to published articles containing past research found on parasites in ducks
Anti-Pluricanonical Systems On Q-Fano Threefolds
We investigate birationality of the anti-pluricanonical map , the
rational map defined by the anti-pluricanonical system , on
-Fano threefolds.Comment: 18 page
Recommendations for observational studies of comorbidity in multiple sclerosis
Objective: To reach consensus about the most relevant comorbidities to study in multiple sclerosis (MS) with respect to incidence, prevalence, and effect on outcomes; review datasets that may support studies of comorbidity in MS; and identify MS outcomes that should be prioritized in such studies. Methods: We held an international workshop to meet these objectives, informed by a systematic review of the incidence and prevalence of comorbidity in MS, and an international survey regarding research priorities for comorbidity. Results: We recommend establishing age- and sex-specific incidence and prevalence estimates for 5 comorbidities (depression, anxiety, hypertension, hyperlipidemia, and diabetes); evaluating the effect of 7 comorbidities (depression, anxiety, hypertension, diabetes, hyperlipidemia, chronic lung disease, and autoimmune diseases) on disability, quality of life, brain atrophy and other imaging parameters, health care utilization, employment, and mortality, including age, sex, race/ethnicity, socioeconomic status, and disease duration as potential confounders; harmonizing study designs across jurisdictions; and conducting such studies worldwide. Ultimately, clinical trials of treating comorbidity in MS are needed. Conclusion: Our recommendations will help address knowledge gaps regarding the incidence, prevalence, and effect of comorbidity on outcomes in MS
Atomic excitation during recollision-free ultrafast multi-electron tunnel ionization
Modern intense ultrafast pulsed lasers generate an electric field of
sufficient strength to permit tunnel ionization of the valence electrons in
atoms. This process is usually treated as a rapid succession of isolated
events, in which the states of the remaining electrons are neglected. Such
electronic interactions are predicted to be weak, the exception being
recollision excitation and ionization caused by linearly-polarized radiation.
In contrast, it has recently been suggested that intense field ionization may
be accompanied by a two-stage `shake-up' reaction. Here we report a unique
combination of experimental techniques that enables us to accurately measure
the tunnel ionization probability for argon exposed to 50 femtosecond laser
pulses. Most significantly for the current study, this measurement is
independent of the optical focal geometry, equivalent to a homogenous electric
field. Furthermore, circularly-polarized radiation negates recollision. The
present measurements indicate that tunnel ionization results in simultaneous
excitation of one or more remaining electrons through shake-up. From an atomic
physics standpoint, it may be possible to induce ionization from specific
states, and will influence the development of coherent attosecond XUV radiation
sources. Such pulses have vital scientific and economic potential in areas such
as high-resolution imaging of in-vivo cells and nanoscale XUV lithography.Comment: 17 pages, 4 figures, original format as accepted by Nature Physic
A Cas9-based toolkit to program gene expression in Saccharomyces cerevisiae
Despite the extensive use of Saccharomyces cerevisiae as a platform for synthetic biology, strain engineering remains slow and laborious. Here, we employ CRISPR/Cas9 technology to build a cloning-free toolkit that addresses commonly encountered obstacles in metabolic engineering, including chromosomal integration locus and promoter selection, as well as protein localization and solubility. The toolkit includes 23 Cas9-sgRNA plasmids, 37 promoters of various strengths and temporal expression profiles, and 10 protein-localization, degradation and solubility tags. We facilitated the use of these parts via a web-based tool, that automates the generation of DNA fragments for integration. Our system builds upon existing gene editing methods in the thoroughness with which the parts are standardized and characterized, the types and number of parts available and the ease with which our methodology can be used to perform genetic edits in yeast. We demonstrated the applicability of this toolkit by optimizing the expression of a challenging but industrially important enzyme, taxadiene synthase (TXS). This approach enabled us to diagnose an issue with TXS solubility, the resolution of which yielded a 25-fold improvement in taxadiene production
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