Experimental verification of multipartite entanglement in quantum networks.

Multipartite entangled states are a fundamental resource for a wide range of quantum information processing tasks. In particular, in quantum networks, it is essential for the parties involved to be able to verify if entanglement is present before they carry out a given distributed task. Here we design and experimentally demonstrate a protocol that allows any party in a network to check if a source is distributing a genuinely multipartite entangled state, even in the presence of untrusted parties. The protocol remains secure against dishonest behaviour of the source and other parties, including the use of system imperfections to their advantage. We demonstrate the verification protocol in a three- and four-party setting using polarization-entangled photons, highlighting its potential for realistic photonic quantum communication and networking applications.

Further development of a transcervical technique for artificial insemination in sheep using previously frozen semen.

A transcervical technique (the Guelph System for transcervical AI) was used to inseminate 2060 ewes on 65 farms (average 31 ewes, range 5 to 107) in Ontario, Canada, from October 1990 to September 1992, using previously frozen semen. Estrus was synchronized using progestagen pessaries and PMSG with median inseminations done at 54 h from pessary removal. Maiden ewes were not included. Only ewes in which the cervix could be penetrated were inseminated with 150 million spermatozoa per insemination. A total of 1809 were penetrated and inseminated (penetration rate 87.8%). Success of penetration increased from 76.3% in the first 500 ewes to 97.9% in the last 500 (P=0.01). Cervical penetration was more successful in ewes in the accelerated lambing program (92.3%, average 3.1 mo since the previous lambing) than those in the annual lambing program (82.4%, average 7.0 mo since the previous lambing; P=0.06). The lambing rate for ewes bred during the combined traditional breeding seasons (Fall of 1990, 1991, 1992) was 50.7% compared to 24.4% for ewes bred at other periods (P=0.00001). The average time required for handling and insemination decreased from 8.62 min in the first 500 ewes to 3.62 min in the last 500 ewes. The Guelph System for Transcervical AI was found to be successful for cervical penetration in most ewes. Penetration success was affected by period since the last lambing and by inseminator experience. The lambing rate was higher for ewes bred during the traditional Fall breeding seasons than during other times of the year.

Comparison of shear bond strengths of some third-generation dentin bonding agents.

Recently a series of new dentin bonding systems has been introduced to the dental profession. These agents are the third generation of systems that have been developed over the past two decades. Some dentin bonding agents are easily applied, clinically, while others are complicated, multi-step procedures. A comparison of the shear bond strengths of five of these systems was made at 15 minutes and after 24 hours stored in water at 37 degrees C.

Computer-assisted advising for dental students.

This article describes a computer-assisted advising system that has been in use at the West Virginia University School of Dentistry for two years. Detailed breakdowns are given for the five data items making up the Student Advising Information Package, and the relevance of each item to the student advising process is noted. A discussion of the overall operation of the system provides information relating to software development for those schools that are now operating with computers or anticipate doing so in the future.

A survey of patient and auxiliary problems as they relate to behavioral dentistry curricula.

The attempt to prepare students to manage problems in their dental practices must be preceded by precise identification of specific problems. The purpose of this study was to identify such problems. A random sample of practicing dentists cited collecting fees, poor patient motivation, patient fear, and broken or cancelled appointments as their most commonly encountered patient problems. The most commonly cited auxiliary problems were retraining auxiliary personnel and poor motivation. The dentists gave support to courses addressing these topics in the third and fourth years of the dental curriculum. The survey supports the increasing emphasis on behavioral dentistry curricula and identifies the most relevant topics for such courses.

Teaching behavioral principles to dental students: a pilot course.

In an effort to amalgamate the study of behavior into the dental curriculum at West Virginia University, four primary objectives were set forth by the authors 1) creating a positive learning experience, 2) providing general information concerning behavior as it relates to dentistry, 3) dealing with special problems related to the human developmental continuum, and 4) increasing the students perception of himself and his patients. These objectives were accomplished through a variety of teaching techniques including formal didactic lectures, open and informal discussions, and videotape exercises involving mock clinical situations. There was no formal grading, although the students were requested to evaluate the course. Generally the students were enthusiastic in their regard for the class, emphasizing their feelings that follow-up courses should be offered.