Surgical glues: are they really adhesive?

Objective: The aim of this study is to create a standard test to approve the efficacy of a surgical sealant. An industrial test, the bulge-and-blister test, which is very convenient for measuring adhesion energy, is applied to the surgical field to quantify adhesion of bioadhesives. Methods: Samples were composed of two circular layers of equine pericardium glued by the surgical sealant studied. The sample was fixed to a support with an industrial glue. The support and the bottom layer were perforated in the centre to allow injection of pressurised water. Water was progressively introduced through the hole in the support and the bottom layer to create a blister with constant radius, increasing height and internal pressure during this first step. At a critical pressure, delamination started, the radius and height of the blister increased and the pressure decreased. At this point, the adhesion energy could be determined. The experimental parameters were measured with a pressure sensor and an optical profilometry device for deflection. Results: Adhesion testing was carried out in eight paired equine pericardium samples bonded with a Dermabond® cyanoacrylate glue. The average value of the practical adhesion energy is 2.3Jm−2 with a standard deviation of 1.5Jm−2. Conclusion: Application of the bulge-and-blister test to the surgical field was achieved and allowed a quantification of adhesion of a surgical glue. Such information is essential to compare the different surgical glues presently available. The study of the impact of bonding conditions such as pressure, hygrometry or setting conditions will provide a better understanding of the characteristics of adhesion in the surgical fiel

Costs of Change, Political Polarization, and Re-Election Hurdles

We develop and study a two-period model of political competition with office- and policymotivated candidates, in which (i) changes of policies impose costs on all individuals and (ii) such costs increase with the magnitude of the policy change. We show that there is an optimal positive level of costs of change that minimizes policy polarization and maximizes welfare. One interpretation of this finding is that societies with intermediate levels of conservatism achieve the highest welfare and the lowest polarization levels. We apply our model to the design of optimal re-election hurdles. In particular, we show that raising the vote-share needed for re-election above 50% weakly reduces policy polarization and tends to increase welfare. Furthermore, we identify circumstances where the optimal re-election hurdle is strictly larger than 50%

Translating the genomics revolution: the need for an international gene therapy consortium for monogenic diseases

Letter to the Edito

Costs of change and political polarization

ISSN:0176-2680ISSN:1873-570

A dynamic model of electoral competition with costly policy changes

We consider an infinite-horizon model of elections where policy changes are costly for citizens and parties. The so-called costs of change increase with the extent of the policy shift and make policy history-dependent. First, we provide a detailed description of the equilibrium dynamics and analyze how policies are influenced by history, costs of change, party polarization, and the incumbent's ability. We show that policies converge to a stochastic alternation between two states and that in the long run costs of change have a moderating effect on policies. Second, we analyze welfare as a function of the marginal cost of change. If the initial level of policy polarization is low, welfare is highest for intermediate marginal costs of change. Moreover, any positive level of costs of change will benefit society if the future is sufficiently valuable. If the initial level of policy polarization is high, however, welfare will be highest for low or zero costs of change

Costs of change, political polarization, and re-election hurdles

We develop and study a two-period model of political competition with office- and policy-motivated candidates, in which (i) changes of policies impose costs on all individuals and (ii) such costs increase with the magnitude of the policy change. We show that there is an optimal positive level of costs of change that minimizes policy polarization and maximizes welfare. One interpretation of this finding is that societies with intermediate levels of conservatism achieve the highest welfare and the lowest polarization levels. We apply our model to the design of optimal re-election hurdles. In particular, we show that raising the vote-share needed for re-election above 50% weakly reduces policy polarization and tends to increase welfare. Furthermore, we identify circumstances where the optimal re-electionhurdle is strictly larger than 50%