1,247 research outputs found
Characteristics of mixed Meloidogyne arenaria and M. incognita populations in flue-cured tobacco
Des expériences en champ ont été poursuivies pendant deux ans afin de caractériser l'association de #Meloidogyne arenaria race 2 (populations Pelion et Govan) et de #M. incognita race 3 sur des plants de tabac résistant à #M. incognita races 1 et 3 ainsi que sur des plants de tabac sensible aux deux espèces. A été également étudié l'effet potentiel de l'infestation par #M. arenaria sur la résistance de l'hôte à #M. incognita races 1 et 3. L'identité spécifique des #Meloidogyne a été établie à la récolte en se fondant sur la longueur des juvéniles de deuxième stade. Les plants de tabac résistants à #M. incognita ne se sont pas montrés prédisposés à l'infestation par #M. incognita lorsqu'ils étaient infestés par #M. arenaria race 2. Le développement des galles sur les racines de tabac résistant à #M. incognita est plus important dans le cas de la population Pelion que dans celui de la population Govan de #M. arenaria. Lors d'infestations mixtes par #M. incognita et #M. arenaria, et avec des traitements équivalents sur plants de tabac sensible, la proportion de la population Govan de #M. arenaria est toujours plus importante (P = 0,05) que celle de la population Pelion. (Résumé d'auteur
A Brachistochrone Approach to Reconstruct the Inflaton Potential
We propose a new way to implement an inflationary prior to a cosmological
dataset that incorporates the inflationary observables at arbitrary order. This
approach employs an exponential form for the Hubble parameter without
taking the slow-roll approximation. At lowest non-trivial order, this
has the unique property that it is the solution to the brachistochrone problem
for inflation.Comment: 13 pages, 2 figures, version matches published versio
Morphological aspects of male and female hands
This is an electronic version of an article published in Annals of Human Biology, 1996, 23(6), 491-494. Annals of Human Biology is available online at informaworldTM http://www.informaworld.com/smpp/content~content=a739339013~db=all~order=pageThis journal article discusses a series of hand radiographs from Gwynedd, North Wales, which were assessed for frequencies in digital and metacarpal formulae between the genders
Heritable risk factors associated with language impairments
There is a strong genetic contribution to children’s language and literacy impairments. The aim of this study was to determine which aspects of the phenotype are familial by comparing 34 parents of probands with language/literacy impairments and 33 parents of typically developing probands. The parents responded to questionnaires regarding previous history for language/reading impairment and participated in psychometric testing. The psychometric test battery consisted of tests assessing non-verbal IQ, short-term memory, articulation, receptive grammar, reading abilities and spelling. Self-report measures demonstrated a higher prevalence of language and literacy impairments in parents of affected probands (32%) compared with parents of unaffected probands (6%). The two groups of parents differed significantly in their performance on the non-word repetition, oromotor and digit span tasks. Non-word repetition gave the best discrimination between the parent groups even when the data from the parents who actually were impaired as ascertained by direct testing or self-report were removed from the analyses. This suggests that non-word repetition serves as a marker of a family risk for language impairment. The paper concludes with a discussion of issues associated with ascertainment of specific language impairment (SLI)
Single-field inflation constraints from CMB and SDSS data
We present constraints on canonical single-field inflation derived from WMAP
five year, ACBAR, QUAD, BICEP data combined with the halo power spectrum from
SDSS LRG7. Models with a non-scale-invariant spectrum and a red tilt n_s < 1
are now preferred over the Harrison-Zel'dovich model (n_s = 1, tensor-to-scalar
ratio r = 0) at high significance. Assuming no running of the spectral indices,
we derive constraints on the parameters (n_s, r) and compare our results with
the predictions of simple inflationary models. The marginalised credible
intervals read n_s = 0.962^{+0.028}_{-0.026} and r < 0.17 (at 95% confidence
level). Interestingly, the 68% c.l. contours favour mainly models with a convex
potential in the observable region, but the quadratic potential model remains
inside the 95% c.l. contours. We demonstrate that these results are robust to
changes in the datasets considered and in the theoretical assumptions made. We
then consider a non-vanishing running of the spectral indices by employing
different methods, non-parametric but approximate, or parametric but exact.
With our combination of CMB and LSS data, running models are preferred over
power-law models only by a Delta chi^2 ~ 5.8, allowing inflationary stages
producing a sizable negative running -0.063^{+0.061}_{-0.049} and larger
tensor-scalar ratio r < 0.33 at the 95% c.l. This requires large values of the
third derivative of the inflaton potential within the observable range. We
derive bounds on this derivative under the assumption that the inflaton
potential can be approximated as a third order polynomial within the observable
range.Comment: 32 pages, 7 figures. v2: additional references, some typos corrected,
passed to JCAP style. v3: minor changes, matches published versio
Heritability of specific language impairment depends on diagnostic criteria
Heritability estimates for specific language impairment (SLI) have been inconsistent. Four twin studies reported heritability of 0.5 or more, but a recent report from the Twins Early Development Study found negligible genetic influence in 4-year-olds. We considered whether the method of ascertainment influenced results and found substantially higher heritability if SLI was defined in terms of referral to speech and language pathology services than if defined by language test scores. Further analysis showed that presence of speech difficulties played a major role in determining whether a child had contact with services. Childhood language disorders that are identified by population screening are likely to have a different phenotype and different etiology from clinically referred cases. Genetic studies are more likely to find high heritability if they focus on cases who have speech difficulties and who have been referred for intervention
Cosmological Parameters Degeneracies and Non-Gaussian Halo Bias
We study the impact of the cosmological parameters uncertainties on the
measurements of primordial non-Gaussianity through the large-scale non-Gaussian
halo bias effect. While this is not expected to be an issue for the standard
LCDM model, it may not be the case for more general models that modify the
large-scale shape of the power spectrum. We consider the so-called local
non-Gaussianity model and forecasts from planned surveys, alone and combined
with a Planck CMB prior. In particular, we consider EUCLID- and LSST-like
surveys and forecast the correlations among and the running of the
spectral index , the dark energy equation of state , the effective
sound speed of dark energy perturbations , the total mass of massive
neutrinos , and the number of extra relativistic degrees of
freedom . Neglecting CMB information on and scales /Mpc, we find that, if is assumed to be known, the
uncertainty on cosmological parameters increases the error on by
10 to 30% depending on the survey. Thus the constraint is
remarkable robust to cosmological model uncertainties. On the other hand, if
is simultaneously constrained from the data, the
error increases by . Finally, future surveys which provide a large
sample of galaxies or galaxy clusters over a volume comparable to the Hubble
volume can measure primordial non-Gaussianity of the local form with a
marginalized 1-- error of the order , after
combination with CMB priors for the remaining cosmological parameters. These
results are competitive with CMB bispectrum constraints achievable with an
ideal CMB experiment.Comment: 17 pages, 1 figure added, typos corrected, comments added, matches
the published versio
Ahnas El Medineh: The Tomb of Paheri at El Kab
Memoir of two excavations at Ahnas.https://knowledge.e.southern.edu/kweeks_coll/1036/thumbnail.jp
A magnetization equation for non-equilibrium spin systems
A magnetization equation for a system of spins evolving non-adiabatically and
out of equilibrium is derived without specifying the internal interactions. For
relaxation processes, this equation provides a general form of magnetization
damping. A special case of the spin-spin exchange interaction is considered.Comment: 9 pages, LATEX file; talk given at Theory Canada III, June 13-16,
2007, University of Alberta, Edmonton; to appear in Canadian Journal of
Physic
Investigating how faculty social networks and peer influence relate to knowledge and use of evidence-based teaching practices
Background: Calls for science education reform have been made for decades in the USA. The recent call to produce one million new science, technology, engineering, and math (STEM) graduates over 10 years highlights the need to employ evidence-based instructional practices (EBIPs) in undergraduate STEM classes to create engaging and effective learning environments. EBIPs are teaching strategies that have been empirically demonstrated to positively impact student learning, attitudes, and achievement in STEM disciplines. However, the mechanisms and processes by which faculty learn about and choose to implement EBIPs remain unclear. To explore this problem area, we used social network analysis to examine how an instructor’s knowledge and use of EBIPs may be influenced by their peers within a STEM department. We investigated teaching discussion networks in biology and chemistry departments at three public universities.
Results: We report that tie strength and tie diversity vary between departments, but that mean indegree is not correlated with organizational rank or tenure status. We also describe that teaching discussion ties can often be characterized as strong ties based on two measures of tie strength. Further, we compare peer influence models and find consistent evidence that peer influence in these departments follows a network disturbances model.
Conclusions: Our findings with respect to tie strength and tie diversity indicate that the social network structures in these departments vary in how conducive they might be to change. The correlation in teaching practice between discussion partner and peer influence models suggest that change agents should consider local social network characteristics when developing change strategies. In particular, change agents can expect that faculty may serve as opinion leaders regardless of their academic rank and that faculty can increase their use of EBIPs even if those they speak to about teaching use EBIPs comparatively less
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