Solvable Critical Dense Polymers on the Cylinder

A lattice model of critical dense polymers is solved exactly on a cylinder with finite circumference. The model is the first member LM(1,2) of the Yang-Baxter integrable series of logarithmic minimal models. The cylinder topology allows for non-contractible loops with fugacity alpha that wind around the cylinder or for an arbitrary number ell of defects that propagate along the full length of the cylinder. Using an enlarged periodic Temperley-Lieb algebra, we set up commuting transfer matrices acting on states whose links are considered distinct with respect to connectivity around the front or back of the cylinder. These transfer matrices satisfy a functional equation in the form of an inversion identity. For even N, this involves a non-diagonalizable braid operator J and an involution R=-(J^3-12J)/16=(-1)^{F} with eigenvalues R=(-1)^{ell/2}. The number of defects ell separates the theory into sectors. For the case of loop fugacity alpha=2, the inversion identity is solved exactly for the eigenvalues in finite geometry. The eigenvalues are classified by the physical combinatorics of the patterns of zeros in the complex spectral-parameter plane yielding selection rules. The finite-size corrections are obtained from Euler-Maclaurin formulas. In the scaling limit, we obtain the conformal partition functions and confirm the central charge c=-2 and conformal weights Delta_t=(t^2-1)/8. Here t=ell/2 and t=2r-s in the ell even sectors with Kac labels r=1,2,3,...; s=1,2 while t is half-integer in the ell odd sectors. Strikingly, the ell/2 odd sectors exhibit a W-extended symmetry but the ell/2 even sectors do not. Moreover, the naive trace summing over all ell even sectors does not yield a modular invariant.Comment: 44 pages, v3: minor correction

Why political context is key in determining the parties interest groups choose to collaborate with

When interest groups choose to collaborate with political parties what determines the type of party they opt to work with? Anne Rasmussen and Simon Otjes write that the two key elements shaping this decision are typically the ideological similarities between the interest group and the party, together with how powerful the party is in terms of its role in government. Outlining a comparison of more than 750 Danish and Dutch interest groups, they note that the extent to which these two factors affect collaboration between interest groups and parties is dependent on the characteristics of political systems

No longer going steady, but playing the field: trade unions and the decline of social democracy

Parties on the centre-left often enjoy a special relationship with trade unions, but recent electoral losses for social democratic parties may limit the ability of unions to influence public policy. Simon Otjes and Anne Rasmussen examine how trade union-party relationships in the Netherlands might be affected by these developments. They argue that the losses suffered by the Social Democrats in the 2017 Dutch elections are unlikely to fundamentally weaken the role of Dutch trade unions in policy-making. Unions enjoy a direct connection to policy-making independent of government composition, and they hold ties to parties across the political spectrum due to the specific trade union traditions present in the country

The influence of university departments on the evolution of entrepreneurial competencies in spin-off ventures

Author's accepted version (postprint).NOTICE: this is the author’s version of a work that was accepted for publication in Research Policy (2014). Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Research Policy (2014), 43(1). doi: http://dx.doi.org/10.1016/j.respol.2013.06.007

Does mental well-being protect against self-harm thoughts and behaviors during adolescence? A six-month prospective investigation

Mental well-being protects against the emergence of suicidal thoughts. However, it is not clear whether these findings extend to self-harm thoughts and behaviors irrespective of intent during adolescence—or why this relationship exists. The current study aimed to test predictions—informed by the integrated motivational–volitional (IMV) model of suicide—concerning the role of perceived defeat and entrapment within the link between mental well-being and self-harm risk. Young people (n = 573) from secondary schools across Scotland completed an anonymous self-report survey at two time points, six months apart, that assessed mental well-being, self-harm thoughts and behaviors, depressive symptomology and feelings of defeat and entrapment. Mental well-being was associated with reduced defeat and entrapment (internal and external) and a decrease in the likelihood that a young person would engage in self-harm thoughts and behaviors. The relationship between mental well-being and thoughts of self-harm was mediated by perceptions of defeat and entrapment (internal and external). Mental well-being was indirectly related to self-harm behaviors via decreased feelings of defeat and internal (but not external) entrapment. Taken together, these findings provide novel insights into the psychological processes linking mental well-being and self-harm risk and highlight the importance of incorporating the promotion of mental well-being within future prevention and early intervention efforts

The role of perceived social support in the relationship between being bullied and mental health difficulties in adolescents

The aim of the study was to test the relationship between experiences of being bullied, cyberbullied, and mental health difficulties, and whether these relationships are moderated by perceived social support and gender. Data were collected from 3737 year 8 pupils (aged 12 and 13 years; 50.1% male) using an online questionnaire. Measures of bullying victimization, perceived social support, and mental health difficulties were included in the online questionnaire. Moderation analyses were conducted to test whether the relationships between being bullied, cyberbullied, and mental health difficulties were moderated by perceived social support and gender. Four models were estimated, each assessing a different source of perceived social support (from family, friends and peers, professional sources, and the perception of having no support). Results of these analyses indicated that across all four models being bullied was significantly associated with mental health difficulties, and being cyberbullied was only significantly associated with poorer mental health difficulties in girls in one of the models. The different sources of perceived social support did not moderate the relationship between experiences of being bullied or cyberbullied and mental health difficulties for either boys or girls. However, significant associations were found between a perceived lack of support, perceived social support from friends and family, and mental health difficulties in girls, but not in boys. The results contribute to a complex body of research findings exploring the role of perceived social support in the relationship between experiences of being bullied and mental health difficulties