Path-sum solution of the Weyl quantum walk in 3 + 1 dimensions.

We consider the Weyl quantum walk in 3+1 dimensions, that is a discrete-time walk describing a particle with two internal degrees of freedom moving on a Cayley graph of the group [Formula: see text], which in an appropriate regime evolves according to Weyl's equation. The Weyl quantum walk was recently derived as the unique unitary evolution on a Cayley graph of [Formula: see text] that is homogeneous and isotropic. The general solution of the quantum walk evolution is provided here in the position representation, by the analytical expression of the propagator, i.e. transition amplitude from a node of the graph to another node in a finite number of steps. The quantum nature of the walk manifests itself in the interference of the paths on the graph joining the given nodes. The solution is based on the binary encoding of the admissible paths on the graph and on the semigroup structure of the walk transition matrices.This article is part of the themed issue 'Second quantum revolution: foundational questions'.

Cervical cancer screening with HPV testing in the Valcamonica (Italy) screening programme.

OBJECTIVE: We present the results of the first screening round and the first year of the second round of the Valcamonica Human Papillomavirus (HPV) pilot screening project. SETTING: From 2010 to 2012, the entire target female population (aged 25-64) was invited to the first HPV screening round in an area where Pap test screening had been active since 2002. METHODS: For HPV-negative women, the interval was three years. For HPV-positive women, a cytological smear was stained and interpreted. Positive cytologies were referred to colposcopy; negatives were referred to repeat HPV after one year. If HPV was persistently positive, women were referred to colposcopy; if negative, to normal screening. RESULTS: In 2010-12 18728 women were screened, slightly higher participation than with Pap test (18233 64.7%); 1633 were HPV-positive (8.7%); 843 were positive at cytology triage (referral rate at baseline 4.5%). Of those referred at the one year HPV test, 84% complied (660/780); 356 were persistently positive (1.9%). The total referral rate was 6.4% compared with 3.7% for the Pap test. The detection rate was 9.2/1000 compared with 5.0% for the Pap test. The HPV positivity rate during the second round in women previously negative was 3.9% and the detection rate in HPV-positive cytology-positive women was 0.8/1000. CONCLUSIONS: HPV-based screening increases colposcopies at the first round, but also strongly increases the detection rate. At the second round, HPV prevalence was much lower and the detection rate also fell, corroborating the need for longer screening intervals in HPV-negative women.

Immunization against bovine herpesvirus-1 infection. Preliminary tests in calves with a DNA vaccine.

A bovine herpesvirus-1 (BHV-1) vaccine expressing glycoprotein D, the form with the transmembrane anchor removed, was evaluated for inducing immunity in calves. The plasmid encoding gD of BHV-1 was injected three times to nine calves, using three animals for each of the following routes: intramuscularly (i.m.), intradermally (i.d.), or intranasally (i.n.). Three additional calves were given the plasmid vector only and served as unvaccinated controls. When calves were subjected to challenge infection with BHV-1, all vaccinated calves as well as the controls developed a typical severe form of infectious bovine rhinotracheitis. However, compared to the controls, the vaccinated calves showed earlier clearance of challenge virus. Moreover, the calves given the vaccine i.m. developed neutralizing antibody to BHV-1 between 21 and 42 days following the first injection of vaccine, whereas in calves vaccinated either i.d. or i.n., as well as the controls, antibody first appeared in their sera 14 days post-challenge infection.