Chiral surfaces self-assembling in one-component systems with isotropic interactions

We show that chiral symmetry can be broken spontaneously in one-component systems with isotropic interactions, i.e. many-particle systems having maximal a priori symmetry. This is achieved by designing isotropic potentials that lead to self-assembly of chiral surfaces. We demonstrate the principle on a simple chiral lattice and on a more complex lattice with chiral super-cells. In addition we show that the complex lattice has interesting melting behavior with multiple morphologically distinct phases that we argue can be qualitatively predicted from the design of the interaction.Comment: 4 pages, 4 figure

Using the uncertainty principle to design simple interactions for targeted self-assembly

We present a method that systematically simplifies isotropic interactions designed for targeted self-assembly. The uncertainty principle is used to show that an optimal simplification is achieved by a combination of heat kernel smoothing and Gaussian screening of the interaction potential in real and reciprocal space. We use this method to analytically design isotropic interactions for self-assembly of complex lattices and of materials with functional properties. The derived interactions are simple enough to narrow the gap between theory and experimental implementation of theory based designed self-assembling materials

Novel self-assembled morphologies from isotropic interactions

We present results from particle simulations with isotropic medium range interactions in two dimensions. At low temperature novel types of aggregated structures appear. We show that these structures can be explained by spontaneous symmetry breaking in analytic solutions to an adaptation of the spherical spin model. We predict the critical particle number where the symmetry breaking occurs and show that the resulting phase diagram agrees well with results from particle simulations.Comment: 4 pages, 4 figure

Sexually transmitted infections (STI) in men who have sex with men (MSM)

The impact of increasingly efficient antiretroviral therapy (ART) on survival and general well-being has contributed to a "business as usual" attitude to sex among men who have sex with men (MSM). There has been a recent marked increase of sexually transmitted infections (STI) including syphilis, LGV and Hepatits C among MSM. STIs located in the oral cavity or rectum are asymptomatic in over 80% and 50%, respectively and these sites must be seen as important reservoirs. On the other hand severe proctitis may be mistreated as inflammatory bowel disease without adequate medical history and testing. Due to the reappearance of syphilis, all genital ulcers, non-itching exanthema and severe disease symptoms (e.g. fever, fatigue, lymphadenopathy, hepato-splenomegaly, increased liver enzymes, neurological and ophthalmologic symptoms without other explanations) should lead to testing for syphilis. There is a marked association between STIs and HIV. Syphilis, LGV and Hepatits C are strongly overrepresented in HIV positive MSM, while gonorrhoea, LGV and syphilis increase the HIV susceptibility. Syphilis leads to increased viral load in HIV positive. The major risk factors for Hepatitis B are number of sex partners and receptive anal intercourse. High grade Human Papilloma Virus (HPV) anal lesions can progress to cancer. There is a 30 fold increase risk for anal cancer among MSM, a risk that is doubled in HIV infection, making anal cancer one of the most common non-AIDS tumors. All MSM should be offered Hepatitis A and B vaccination and the inclusion of boys in HPV vaccination programs must be considered. The aim of this article is to describe asymptomatic and symptomatic bacterial and viral STIs of the oral cavity, penis/urethra and rectum and the sexually transmittable viral Hepatitis and HIV in MSM and to inspire the medical establishment to adhere to testing guidelines in this group. This article is built on a review of published findings, the presentation of own data on Gonorrhoea and chlamydia and our own experience in treating all STIs including HIV in MSM since 1982 at a Gay Men's Health Clinic (Venhälsan) at Stockholm South General Hospital, Sweden

Designing isotropic interactions for self-assembly of complex lattices

We present a direct method for solving the inverse problem of designing isotropic potentials that cause self-assembly into target lattices. Each potential is constructed by matching its energy spectrum to the reciprocal representation of the lattice to guarantee that the desired structure is a ground state. We use the method to self-assemble complex lattices not previously achieved with isotropic potentials, such as a snub square tiling and the kagome lattice. The latter is especially interesting because it provides the crucial geometric frustration in several proposed spin liquids.Comment: 4 pages, 3 figure

Turbulence and jet-driven zonal flows: Secondary circulation in rotating fluids due to asymmetric forcing

We report on experiments and modeling on a rotating confined liquid that is forced by circumferential jets coaxial with the rotation axis, wherein system-scale secondary flows are observed to emerge. The jets are evenly divided in number between inlets and outlets and have zero net mass transport. For low forcing strengths the sign of this flow depends on the sign of a sloped end cap, which simulates a planetary β plane. For increased forcing strengths the secondary flow direction is insensitive to the slope sign, and instead appears to be dominated by an asymmetry in the forcing mechanism, namely, the difference in radial divergence between the inlet and outlet jet profiles. This asymmetry yields a net radial velocity that is affected by the Coriolis force, inducing secondary zonal flow