Fast calculation of the electrostatic potential in ionic crystals by direct summation metho

An efficient real space method is derived for the evaluation of the Madelung's potential of ionic crystals. The proposed method is an extension of the Evjen's method. It takes advantage of a general analysis for the potential convergence in real space. Indeed, we show that the series convergence is exponential as a function of the number of annulled multipolar momenta in the unit cell. The method proposed in this work reaches such an exponential xconvergence rate. Its efficiency is comparable to the Ewald's method, however unlike the latter, it uses only simple algebraic functions

A Presheaf Interpretation of the Generalized Freyd Conjecture

We give a generalized version of the Freyd conjecture and a way to think about a possible proof. The essential point is to describe an elementary formal reduction of the question that holds in any triangulated category. There are no new results, but at least one known example drops out quite trivially.Comment: 8 pages; formerly titled "Thinking about the Freyd conjecture

Insights about Diversity of Tetrabothriidae (Eucestoda) among Holarctic Alcidae (Charadriiformes): What Is \u3ci\u3eTetrabothrius jagerskioeldi\u3c/i\u3e?

Tetrabothriid cestodes are characteristic helminths that infect species of seabirds globally. We begin with the exploration of the diversity of tapeworms of the genus Tetrabothrius Rudolphi, 1819 (Eucestoda: Tetrabothriidae), some of which are distributed among seabirds of the family Alcidae (Charadriiformes) at boreal to higher latitudes of Holarctic seas. During the course of 2 decades of field inventory from 1975 through the early 1990s (in addition to earlier collections assembled by Robert L. Rausch and colleagues in Alaska initiated in the late 1940s), an extensive series of tapeworm specimens attributable to species of Tetrabothrius was recovered from seabirds across the North Pacific Basin. It was assumed based on published records of species richness in this fauna that a single species, Tetrabothrius jagerskioeldi Nybelin, 1916, would predominate among alcid hosts. In contrast, detailed study revealed considerable morphological complexity that could not be accommodated within a single species. Further, it was apparent that the limits for the primary morphological attributes of T. jagerskioeldi were not clearly defined. We redescribe T. jagerskioeldi based on direct examination of the type series of specimens from Sweden and an assemblage of specimens largely from alcid hosts from the North Pacific basin. Specimens of T. jagerskioeldi are diagnosed by a characteristic configuration of the genital atrium, position of the male and female genital canals, structure of the male and female organ systems, and numbers of testes. Based on the spectrum of characters we explored, it was apparent that numerous specimens of Tetrabothrius among genera and species of Alcidae from the North Pacific inventory could not be accommodated in T. jagerskioeldi and provisionally are referred to Tetrabothrius undescribed n. sp. pending ongoing evaluations. Superficially, these are all large and robust tapeworms referable to Tetrabothrius, potentially contributing to misidentifications and misattribution that have occurred both in the literature and in the few archived specimens in museums. We summarize the results of extensive inventory collections since 1950, establishing a distributional baseline for species of Tetrabothrius from a wide range of geographic localities and an assemblage of host species among the Alcidae and some species of Laridae, Stercorariidae, and Phalacrocoracidae. We further evaluate the validity of historical published records for T. jagerskioeldi and other congeners among alcids and other seabirds. A conclusion that emerges is that T. jagerskioeldi is a rare tapeworm with a patchy distribution in pelagic to nearshore marine environments, showing considerable heterogeneity in space and time, among alcid seabirds across high-latitude seas of the Holarctic. Prior concepts for host range require reevaluation. We demonstrate that the associations for T. jagerskioeldi are relatively narrow and appear to involve a more limited spectrum of alcid hosts, and less often other species of marine birds, than currently assumed. A robust understanding of parasite species diversity and distribution is critical in establishing baselines across marine ecosystems. Our current study among species of Tetrabothrius, especially in the North Pacific basin and Bering Sea ecosystem contributes to development of a series of specimen-centered baselines derived primarily from the late 1970s to the early 1980s against which accelerating perturbations linked to climate warming and ocean-atmosphere interactions may be explored. Detailed knowledge of specimen-based faunal diversity for parasites provides a cumulative, temporal, and spatial snapshot and proxy for conditions in marine foodwebs and the continuity of trophic linkages

The construction, utilization, and evaluation of a series of exercises designed to improve the oral language of second grade children

Thesis (Ed.M.)--Boston Universit

Contrasting Experimentally Device-Manipulated and Device-Free Smiles.

Researchers in psychology have long been interested in not only studying smiles, but in examining the downstream effects of experimentally manipulated smiles. To experimentally manipulate smiles unobtrusively, participants typically hold devices (e.g., pens or chopsticks) in their mouths in a manner that activates the muscles involved in smiling. Surprisingly, despite decades of research using these methods, no study has tested to what degree these methods activate the same muscles as more natural, device-free smiles. Our study fills this gap in the literature by contrasting the magnitude of muscle activation in device-free smiles against the popular chopstick/pen manipulation. We also contrast these methods against the Smile Stick, a new device specifically designed to manipulate smiles in a comfortable and hygienic fashion. One hundred fifty-nine participants each participated in three facial expression manipulations that were held for 1 min: smile manipulation via Smile Stick, smile manipulation via chopsticks, and device-free smile. Facial electromyography was used to measure the intensity of the activation of the two main types of muscles involved in genuine, Duchenne smiling: the orbicularis oculi (a muscle group around the eyes) and the zygomaticus major (a muscle group in the cheeks). Furthermore, following each manipulation, participants rated their experience of the manipulation (i.e., comfort, fatigue, and difficulty), experienced affect (positive and negative), and levels of arousal. Results indicated that the Smile Stick and chopsticks performed equally across all measurements. Device-free smiles were rated as most comfortable but also the most fatiguing, and procured the greatest levels of positive affect and lowest levels of negative affect. Furthermore, device-free smiles resulted in significantly higher levels of both zygomaticus major (by ∼40%) and orbicularis oculi (by ∼15%) muscle activation than either the Smile Stick or chopsticks. The two devices were not different from each other in muscle activation. This study reveals that while device-free smiling procures the greatest changes in muscle activation and affect change, smiling muscle groups are activated by device manipulations, and expected changes in affect do occur, albeit to a lesser degree than device-free smiling. It also indicates that the Smile Stick is an acceptable and comparable alternative to disposable chopsticks

A catch-free stock assessment model with application to goliath grouper (Epinephelus itajara) off southern Florida

Many modern stock assessment methods provide the machinery for determining the status of a stock in relation to certain reference points and for estimating how quickly a stock can be rebuilt. However, these methods typically require catch data, which are not always available. We introduce a model-based framework for estimating reference points, stock status, and recovery times in situations where catch data and other measures of absolute abundance are unavailable. The specif ic estimator developed is essentially an age-structured production model recast in terms relative to pre-exploitation levels. A Bayesian estimation scheme is adopted to allow the incorporation of pertinent auxiliary information such as might be obtained from meta-analyses of similar stocks or anecdotal observations. The approach is applied to the population of goliath grouper (Epinephelus itajara) off southern Florida, for which there are three indices of relative abundance but no reliable catch data. The results confirm anecdotal accounts of a marked decline in abundance during the 1980s followed by a substantial increase after the harvest of goliath grouper was banned in 1990. The ban appears to have reduced fishing pressure to between 10% and 50% of the levels observed during the 1980s. Nevertheless, the predicted fishing mortality rate under the ban appears to remain substantial, perhaps owing to illegal harvest and depth-related release mortality. As a result, the base model predicts that there is less than a 40% chance that the spawning biomass will recover to a level that would produce a 50% spawning potential ratio

Effects of preconditioning and extrusion of linseed on the ruminal biohydrogenation of fatty acids 1. In vivo studies

The extent and intermediates of ruminal biohydrogenation (BH) of fatty acids (FA) from a blend of linseed and wheat bran (70:30) were investigated in the rumen fluid, rumen particle phase and duodenal flow. The blend was ground through a 3 mm screen and used raw or extruded, or was ground through a 6 mm screen and preconditioned. Three dry Holstein cows fitted with ruminal and duodenal cannulas were used in a 3 × 3 Latin square design, with 18 days adaptation. The diet contained 20% (DM basis) of the linseed based blend. Twelve samples taken over 3 days were composited for analysis of rumen fluid, rumen particle phase and duodenal flow. The BH of FA from linseed resulted in the appearance of a great number of C18:1 intermediates, among which trans-10+11 to trans-16C18:1 were the most abundant. The proportion of cis-9,trans-11C18:2 was low. Preconditioning coarsely ground linseed resulted in a lower extent of C18:2 and C18:3 BH, and lower proportions of trans-12 to trans-16C18:1 intermediates than extrusion or a lack of processing of finely ground linseed. On the contrary, extrusion did not affect the extent of BH and had no significant effect on the proportions of trans-C18:1 intermediates, but increased the proportion of cis-9,trans-11C18:2 in both rumen phases. Different digesta types resulted in different estimates of BH. The extent of BH and the proportions of trans-C18:1 intermediates were lower in the rumen particle phase and higher in the rumen fluid than in the duodenum. Moreover, interactions between digesta type and treatment of linseed were observed