Using a cognitive architecture to examine what develops

Different theories of development propose alternative mechanisms by which development occurs. Cognitive architectures can be used to examine the influence of each proposed mechanism of development while keeping all other mechanisms constant. An ACT-R computational model that matched adult behavior in solving a 21-block pyramid puzzle was created. The model was modified in three ways that corresponded to mechanisms of development proposed by developmental theories. The results showed that all the modifications (two of capacity and one of strategy choice) could approximate the behavior of 7-year-old children on the task. The strategy-choice modification provided the closest match on the two central measures of task behavior (time taken per layer, r = .99, and construction attempts per layer, r = .73). Modifying cognitive architectures is a fruitful way to compare and test potential developmental mechanisms, and can therefore help in specifying “what develops.

Sums of magnetic eigenvalues are maximal on rotationally symmetric domains

The sum of the first n energy levels of the planar Laplacian with constant magnetic field of given total flux is shown to be maximal among triangles for the equilateral triangle, under normalization of the ratio (moment of inertia)/(area)^3 on the domain. The result holds for both Dirichlet and Neumann boundary conditions, with an analogue for Robin (or de Gennes) boundary conditions too. The square similarly maximizes the eigenvalue sum among parallelograms, and the disk maximizes among ellipses. More generally, a domain with rotational symmetry will maximize the magnetic eigenvalue sum among all linear images of that domain. These results are new even for the ground state energy (n=1).Comment: 19 pages, 1 figur

Geophysical Exploration of Vesta

Dawn’s year-long stay at Vesta allows comprehensive mapping of the shape, topography, geology, mineralogy, elemental abundances, and gravity field using it’s three instruments and highprecision spacecraft navigation. In the current Low Altitude Mapping Orbit (LAMO), tracking data is being acquired to develop a gravity field expected to be accurate to degree and order ~20 [1, 2]. Multi-angle imaging in the Survey and High Altitude Mapping Orbit (HAMO) has provided adequate stereo coverage to develop a shape model accurate to ~10 m at 100 m horizontal spatial resolution. Accurate mass determination combined with the shape yields a more precise value of bulk density, albeit with some uncertainty resulting from the unmeasured seasonally-dark north polar region. The shape and gravity of Vesta can be used to infer the interior density structure and investigate the nature of the crust, informing models for Vesta’s formation and evolution

IJED support for eating disorders research in the time of COVID‐19

This editorial reports on an anonymous survey question posed to eating disorders researchers about changes the International Journal of Eating Disorders (IJED) should implement to support the eating disorders research community affected by COVID‐19. The editorial accompanies an IJED article that details responses to the larger survey focusing more broadly on COVID‐19‐related research disruptions. Survey invitations were sent to editorial board members of eating disorders journals, members of eating disorder scientific organizations (e.g., Eating Disorders Research Society), and individuals who provided at least three IJED reviews in the prior 12 months. We reviewed the responses of 187 participants and identified three categories of changes that: (a) had already been implemented by the journal, (b) cannot be implemented because they fall outside the scope of IJED, or (c) will be implemented in coming weeks or months. The latter category includes publishing topical COVID‐19 papers, making some COVID‐19‐related content available open access, revising statistical guidelines, and issuing author guidance on reporting protocol changes caused by COVID‐19‐related disruptions. IJED recognizes the disruptive impacts that COVID‐19 has on all activities in our field, including clinical work, teaching, and advocacy, and is committed to supporting authors during this difficult time while striving to publish high‐quality research

Oil content and physicochemical characteristics of some wild oilseed plants from Kivu region Eastern Democratic Republic of Congo

Seeds were collected from Carapa grandiflora, Carapa procera, Cardiospermum halicacabum, Maesopsis eminii, Millettia dura, Myrianthus arboreus, Myrianthus holstii, Pentaclethra macrophylla, Podocarpus usambarensis, Tephrosia vogelii and Treculia africana from Kahuzi-Biega National Park and the surrounding areas in D.R. Congo. Oils were extracted using ethyl ether in Soxhlet extractor. Physicochemical characteristics were determined using the methods of the American Oil Chemists Society. The seed oil content obtained ranged from 17.2 to 64.4%; the highest was obtained from P. usambarensis and the lowest from T. vogelii. The oil specific gravity varied from 0.8050 to 0.9854; the oils melting point ranged from -12 to 32°C; the oil saponification values from 182.5 to 260.9 mg KOH/g; the oil acidity index from 1.74 to 5.31 mg KOH/g and the unsaponifiable matter from 0.54 to 2.25%. The plant seed oils content reported in this study are comparatively higher than some food crop plants such as soybean and olive. Five of these oils have oil melting range as that of edible oils. C. grandiflora, C. halicacabum, M. eminii and the two species of Myrianthus are in the range of common cooking oils by their specific gravity values. P. usambarensis seed oil with its relatively high unsaponifiable matter content can have efficacy as cosmetic.Keywords: Physicochemical characteristics, oil content, oilseed plants, Kahuzi-Biega National Park, edible oil

Influence of simultaneous doping of Sb & Pb on phase formation, superconducting and microstructural characteristics of HgBa2Ca2Cu3O8+\delta

We report systematic studies of structural, microstructural and transport properties of (Hg_0.80 Sb_0.2-x Pb_x)Ba_2 Ca_2 Cu_3O_8+\delta (where x = 0.0, 0.05, 0.1, 0.15, 0.2) compounds. Bulk polycrystalline samples have been prepared by two-step solid-state reaction route at ambient pressure. It has been observed that simultaneous substitution of Sb and Pb at Hg site in oxygen deficient HgO_\delta layer of HgBa2Ca2Cu3O8+\delta cuprate high-Tc superconductor leads to the formation of Hg-1223 as the dominant phase. Microstructural investigations of the as grown samples employing scanning electron microscopy reveal single crystal like large grains embodying spiral like features. Superconducting properties particularly transport current density (Jct) have been found to be sensitive to these microstructural features. As for example (Hg0.80Sb0.05Pb0.15)Ba2Ca2Cu3O8+\delta compound which exhibits single crystal like large grains (~ 50 micrometer) and appears to result through spiral growth mechanism, shows highest Jct (~ 1.85 x 103 A/cm2) at 77K. A possible mechanism for the generation of spiral like features and correlation between microstructural features and superconducting properties have been put forward.Comment: 16 pages, 6 figures. Accepted in Physica

Anomalous diffusion and anisotropic nonlinear Fokker-Planck equation

We analyse a bidimensional nonlinear Fokker-Planck equation by considering an anisotropic case, whose diffusion coefficients are $D_x \propto |x|^{-\theta}$ and $D_y \propto |y|^{-\gamma}$ with $\theta, \gamma \in {\cal{R}}$. In this context, we also investigate two situations with the drift force $\vec{F}(\vec{r},t)=(-k_{x}x, -k_y y)$. The first one is characterized by $k_x/k_y=(2+\gamma)/(2+\theta)$ and the second is given by $k_{x}=k$ and $k_{y}=0$. In these cases, we can verify an anomalous behavior induced in different directions by the drift force applied. The found results are exact and exhibit, in terms of the $q$-exponentials, functions which emerge from the Tsallis formalism. The generalization for the $D$-dimensional case is discussed.Comment: 6 pages, tex fil

Changes in anti-viral effectiveness of interferon after dose reduction in chronic hepatitis C patients: a case control study

BACKGROUND: High dose interferon induction treatment of hepatitis C viral infection blocks viral production over 95%. Since dose reduction is often performed due to clinical considerations, the effect of dose reduction on hepatitis C virus kinetics was studied. METHODS: A new model that allowed longitudinal changes in the parameters of viral dynamics was used in a group of genotype-1 patients (N = 15) with dose reduction from 10 to 3 million units of interferon daily in combination with ribavirin, in comparison to a control group (N = 9) with no dose reduction. RESULTS: Dose reduction gave rise to a complex viral kinetic pattern, which could be only explained by a decrease in interferon effectiveness in blocking virion production. The benefit of the rapid initial viral decline following the high induction dose is lost after dose reduction. In addition, in some patients also the second phase viral decline slope, which is highly predictive of success of treatment, was impaired by the dose reduction resulting in smaller percentage of viral clearance in the dose reduction group. CONCLUSIONS: These findings, while explaining the failure of many induction schedules, suggest that for genotype-1 patients induction therapy should be continued till HCVRNA negativity in serum in order to increase the sustained response rate for chronic hepatitis C

A posteriori inclusion of parton density functions in NLO QCD final-state calculations at hadron colliders: The APPLGRID Project

A method to facilitate the consistent inclusion of cross-section measurements based on complex final-states from HERA, TEVATRON and the LHC in proton parton density function (PDF) fits has been developed. This can be used to increase the sensitivity of LHC data to deviations from Standard Model predictions. The method stores perturbative coefficients of NLO QCD calculations of final-state observables measured in hadron colliders in look-up tables. This allows the posteriori inclusion of parton density functions (PDFs), and of the strong coupling, as well as the a posteriori variation of the renormalisation and factorisation scales in cross-section calculations. The main novelties in comparison to original work on the subject are the use of higher-order interpolation, which substantially improves the trade-off between accuracy and memory use, and a CPU and computer memory optimised way to construct and store the look-up table using modern software tools. It is demonstrated that a sufficient accuracy on the cross-section calculation can be achieved with reasonably small look-up table size by using the examples of jet production and electro-weak boson (Z, W) production in proton-proton collisions at a center-of-mass energy of 14 TeV at the LHC. The use of this technique in PDF fitting is demonstrated in a PDF-fit to HERA data and simulated LHC jet cross-sections as well as in a study of the jet cross-section uncertainties at various centre-of-mass energies