817 research outputs found
ForeCAT - a model for magnetic deflections of coronal mass ejections
Frequently, the Sun explosively releases bubbles of magnetized plasma known as coronal mass ejections (CMEs), which can produce adverse space weather effects at Earth. Accurate space weather forecasting requires knowledge of the trajectory of CMEs. Decades of observations show that CMEs can deflect from a purely radial trajectory, however, no consensus exists as to the cause of these deflections. We developed a model for CME deflection and rotation from magnetic forces, called Forecasting a CME's Altered Trajectory (ForeCAT). ForeCAT has been designed to run fast enough for large parameter phase space studies, and potentially real-time predictions.
ForeCAT reproduces the general trends seen in observed CME deflections. In particular, CMEs deflect toward regions of minimum magnetic energy - frequently the Heliospheric Current Sheet (HCS) on global scales. The background magnetic forces decrease rapidly with distance and quickly become negligible. Most deflections and rotations can be well-described by assuming constant angular momentum beyond 10 Rs.
ForeCAT also reproduces individual observed CME deflections - the 2008 December 12, 2008 April 08, and 2010 July 12 CMEs. By determining the reduced chi-squared best fit between the ForeCAT results and the observations we constrain parameters related to the CME and the background solar wind. Additionally, we constrain whether different models for the low corona magnetic backgrounds can produce the observed CME deflection.
We explore the space weather of cool M dwarfs (dMs) with surface magnetic field strengths of order kG. dMs have extreme CMEs and flares and close-in habitable zones. We use ForeCAT to explore the deflections corresponding to the range of plausible CME masses and speeds for the dM V374 Peg. The deflection of the dM CMEs exceeds their solar counterparts, and the strong magnetic gradients surrounding the dM's Astrospheric Current Sheet (ACS, analogous to the Sun's HCS) can trap the CMEs that reach it. Exoplanets which orbit in the plane of the ACS will suffer CME impacts 10 times more often than exoplanets with inclined orbits and are therefore less likely to retain an atmosphere than exoplanets with inclined orbits
Reproductive and developmental effects of phthalate diesters in females.
Phthalate diesters, widely used in flexible plastics and consumer products, have become prevalent contaminants in the environment. Human exposure is ubiquitous and higher phthalate metabolite concentrations documented in patients using medications with phthalate-containing slow release capsules raises concerns for potential health effects. Furthermore, animal studies suggest that phthalate exposure can modulate circulating hormone concentrations and thus may be able to adversely affect reproductive physiology and the development of estrogen sensitive target tissues. Therefore, we conducted a systematic review of the epidemiological and experimental animal literature examining the relationship between phthalate exposure and adverse female reproductive health outcomes. The epidemiological literature is sparse for most outcomes studied and plagued by small sample size, methodological weaknesses, and thus fails to support a conclusion of an adverse effect of phthalate exposure. Despite a paucity of experimental animal studies for several phthalates, we conclude that there is sufficient evidence to suggest that phthalates are reproductive toxicants. However, we note that the concentrations needed to induce adverse health effects are high compared to the concentrations measured in contemporary human biomonitoring studies. We propose that the current patchwork of studies, potential for additive effects and evidence of adverse effects of phthalate exposure in subsequent generations and at lower concentrations than in the parental generation support the need for further study
Cosmid Cloning of Five \u3cem\u3eZymomonas trp\u3c/em\u3e Genes by Complementation of \u3cem\u3eEscherichia coli\u3c/em\u3e and \u3cem\u3ePseudomonas putida trp\u3c/em\u3e Mutants
A library of Zymomonas mobilis genomic DNA was constructed in the broad-host-range cosmid pLAFR1. The library was mobilized into a variety of Escherichia coli and Pseudomonas putida trp mutants by using the helper plasmid pRK2013. Five Z. mobilis trp genes were identified by the ability to complement the trp mutants. The trpF, trpB, and trpA genes were on one cosmid, while the trpD and trpC genes were on two separate cosmids. The organization of the Z. mobilis trp genes seems to be similar to the organization found in Rhizobium spp., Acinetobacter calcoaceticus, and Pseudomonas acidovorans. The trpF, trpB, and trpA genes appeared to be linked, but they were not closely associated with trpD or trpC genes
The Impact of Professional Development on Trauma-Informed Practices (TIPs) in a Teacher\u27s Feeling of Self-Efficacy
The purpose of this quantitative, quasi-experimental, static-group comparison design study was to determine the increase or decrease of self-efficacy for elementary and secondary teachers regarding instructional strategies, student engagement, and classroom management after professional development in TIPs. TIPs in the school setting provide comprehensive interventions to address childhood trauma that could promote positive academic progress. There has been little research provided on the impact of TIPs regarding instructional strategies, student engagement, and classroom management as it relates to teacher-efficacy. The results of this study found significant differences in survey responses from teachers in two school districts. The Teachersā Sense of Efficacy Scale (TSES) was utilized to collect data on teacherās sense of self- efficacy from 100 teachers in two urban school districts in Mississippi. According to the results of three independent t tests, there is an indication that TIPs may impact teacher self-efficacy. Teachers do not receive appropriate training at the university level to overcome the effects of trauma in the classroom setting; therefore, professional development in TIPs should be implemented at the school level. The researcher recommends further research into the role of TIPs at improving social-emotional learning of students and increasing teacher self-efficacy
Children and young peopleās participation rights:Looking backwards and moving forwards
Children and young peopleās participation is an ever-growing demand. Thirty years on from the UN Convention on the Rights of the Childās adoption, however, fundamental challenges continue for participation that are widely recognised cross-nationally but remain stubbornly consistent. As a way in to considering the children and young peopleās participation literature more generally, all articles referring to participation in their titles were identified from The International Journal of Childrenās Rights. These 56 articles were analysed to identify trends, challenges and opportunities. The analysis found: a remarkably consistent narrative on participation over the 30 years; limitations on domains considered, geography and conceptual clarity; and far more written about challenges than solutions. Drawing on these findings and considering the participation literature more generally, the article recommends that the field expands its geographic and intellectual boundaries, uses powerful concepts like agency, competency and autonomy with greater precision, and explores fresh ideas like child protoganism, activism and children as human rights defenders
The use of statistical classifiers for the discrimination of species of the genus Gyrodactylus (Monogenea) parasitizing salmonids
This study applies flexible statistical methods to morphometric measurements obtained via light and scanning electron microscopy (SEM) to discriminate closely related species of Gyrodactylus parasitic on salmonids. For the first analysis, morphometric measurements taken from the opisthaptoral hooks and bars of 5 species of gyrodactylid were derived from images obtained by SEM and used to assess the prediction performance of 4 statistical methods (nearest neighbours; feed-forward neural network; projection pursuit regression and linear discriminant analysis). The performance of 2 methods, nearest neighbours and a feed-forward neural network provided perfect discrimination of G. salaris from 4 other species of Gyrodactylus when using measurements taken from only a single structure, the marginal hook. Data derived from images using light microscopy taken from the full complement of opisthaptoral hooks and bars were also tested and nearest neighbours and linear discriminant analysis gave perfect discrimination of G. salaris from G. derjavini Mikailov, 1975 and G. truttae GlƤser, 1974. The nearest neighbours method had the least misclassifications and was therefore assessed further for the analysis of individual hooks. Five morphometric parameters from the marginal hook subset (total length, shaft length, sickle length, sickle proximal width and sickle distal width) gave near perfect discrimination of G. salaris. For perfect discrimination therefore, larger numbers of parameters are required at the light level than at the SEM level
The Influence of Sexual Assault and Fear of Crime on Judgments of Rational Discrimination
Female undergraduates rated the rationality of using gender stereotypes in several potentially dangerous situations. We tested whether sexual assault history and fear of crime moderated perceptions of the use of gender stereotypes in public and private settings. Primary results revealed differences in ratings among victims and nonvictims of sexual assault as a function of type of setting. Additionally, fear of crime increased ratings of rationality in nighttime public situations. The implications of these results are discussed in the context of the ārational discriminationā phenomenon (Khan & Lambert, 2001)
Motor Timing Intraindividual Variability in Amnestic Mild Cognitive Impairment and Cognitively Intact Elders at Genetic Risk for Alzheimerās Disease
Introduction: Intraindividual variability (IIV) in motor performance has been shown to predict future cognitive decline. The apolipoprotein E-epsilon 4 (APOE-Īµ4) allele is also a well-established risk factor for memory decline. Here, we present novel findings examining the influence of the APOE-Īµ4 allele on the performance of asymptomatic healthy elders in comparison to individuals with amnestic MCI (aMCI) on a fine motor synchronization, paced finger-tapping task (PFTT).
Method: Two Alzheimerās disease (AD) risk groups, individuals with aMCI (n = 24) and cognitively intact APOE-Īµ4 carriers (n = 41), and a control group consisting of cognitively intact APOE-Īµ4 noncarriers (n = 65) completed the Rey Auditory Verbal Learning Test and the PFTT, which requires index finger tapping in synchrony with a visual stimulus (interstimulus interval = 333 ms).
Results: Motor timing IIV, as reflected by the standard deviation of the intertap interval (ITI), was greater in the aMCI group than in the two groups of cognitively intact elders; in contrast, all three groups had statistically equivalent mean ITI. No significant IIV differences were observed between the asymptomatic APOE-Īµ4 carriers and noncarriers. Poorer episodic memory performance was associated with greater IIV, particularly in the aMCI group.
Conclusions: Results suggest that increased IIV on a fine motor synchronization task is apparent in aMCI. This IIV measure was not sensitive in discriminating older asymptomatic individuals at genetic risk for AD from those without such a genetic risk. In contrast, episodic memory performance, a well-established predictor of cognitive decline in preclinical AD, was able to distinguish between the two cognitively intact groups based on genetic risk
- ā¦