Bond Strength of an Amorphous Calcium Phosphate–Containing Orthodontic Adhesive

Objective: To determine whether an amorphous calcium phosphate (ACP)-containing adhesive has an acceptable level of shear bond strength to be used as an orthodontic adhesive. Materials and Methods: Sixty extracted premolars were randomly divided into three groups for orthodontic bonding. Group 1 used a composite resin adhesive (Transbond XT), group 2 was bonded with an ACP-containing adhesive (Aegis Ortho), and group 3 used a resin-modified glass ionomer (Fuji Ortho LC). All bonded teeth were stored in distilled water at 37°C for 40 ± 2 hours prior to debonding. Shear bond strength and adhesive remnant index (ARI) were recorded for each specimen. Results: The mean shear bond strengths for the three test groups were: group 1 (15.2 ± 3.6 MPa), group 2 (6.6 ± 1.5 MPa), and group 3 (8.3 ± 2.8 MPa). A one-way analysis of variance showed a significant difference in bond strengths between the groups. A post hoc Tukey test showed group 1 to be significantly (P \u3c .001) greater than groups 2 and 3. A Kruskal-Wallis test and a Mann-Whitney U-test showed groups 1 and 3 exhibited lower ARI scores than group 2, but a majority of specimens in each group had greater than 50% of the cement removed along with the bracket during debonding. Conclusions: The ACP-containing adhesive demonstrated a low, but satisfactory bond strength needed to function as an orthodontic adhesive

DIFFERENCES IN U.S. CONSUMER PREFERENCES FOR CERTIFIED PORK CHOPS WHEN FACING BRANDED VS. NON-BRANDED CHOICES

Consumers' preferences for credence attributes of a product may differ from each other, when facing the choices between branded and/or non-branded products. We test this hypothesis with conditional and mixed logit regression using data obtained by choice experiment surveys. The results suggest that, on average, consumers are willing to pay more for a certification attribute when the product is branded. Additionally, greater variation in consumer willingness-to-pay is observed in the non-branded case. This latter characteristic of the results may represent the increased uncertainty some consumers internalize concerning quality consistency when brand information is not provided. These results have interesting implications for producers, processors, retailers, and policy makers.Consumer/Household Economics,

Integrated On-Farm Decision Making: Economic Implications of Increased Variation in Litter Size

Increased litter sizes and associated piglet performance consequences, challenge swine producers. Stochastic modeling captured bioeconomic performance of individual piglets. As average litter size increased from 8.8 to 20.8 piglets, costs and revenues per head marketed from the demonstration herd decreased and total profit increased at a decreasing rate.stochastic modeling, farm business management, swine litter size, Agribusiness, Farm Management, Livestock Production/Industries,

Link and subgraph likelihoods in random undirected networks with fixed and partially fixed degree sequence

The simplest null models for networks, used to distinguish significant features of a particular network from {\it a priori} expected features, are random ensembles with the degree sequence fixed by the specific network of interest. These "fixed degree sequence" (FDS) ensembles are, however, famously resistant to analytic attack. In this paper we introduce ensembles with partially-fixed degree sequences (PFDS) and compare analytic results obtained for them with Monte Carlo results for the FDS ensemble. These results include link likelihoods, subgraph likelihoods, and degree correlations. We find that local structural features in the FDS ensemble can be reasonably well estimated by simultaneously fixing only the degrees of few nodes, in addition to the total number of nodes and links. As test cases we use a food web, two protein interaction networks (\textit{E. coli, S. cerevisiae}), the internet on the autonomous system (AS) level, and the World Wide Web. Fixing just the degrees of two nodes gives the mean neighbor degree as a function of node degree, $_k$, in agreement with results explicitly obtained from rewiring. For power law degree distributions, we derive the disassortativity analytically. In the PFDS ensemble the partition function can be expanded diagrammatically. We obtain an explicit expression for the link likelihood to lowest order, which reduces in the limit of large, sparse undirected networks with $L$ links and with $k_{\rm max} \ll L$ to the simple formula $P(k,k') = kk'/(2L + kk')$. In a similar limit, the probability for three nodes to be linked into a triangle reduces to the factorized expression $P_{\Delta}(k_1,k_2,k_3) = P(k_1,k_2)P(k_1,k_3)P(k_2,k_3)$.Comment: 17 pages, includes 11 figures; first revision: shortened to 14 pages (7 figures), added discussion of subgraph counts, deleted discussion of directed network