Phonon-mediated repulsion, sharp transitions and (quasi)self-trapping in the extended Peierls-Hubbard model.

We study two identical fermions, or two hard-core bosons, in an infinite chain and coupled to phonons by interactions that modulate their hopping as described by the Peierls/Su-Schrieffer-Heeger (SSH) model. We show that exchange of phonons generates effective nearest-neighbor repulsion between particles and also gives rise to interactions that move the pair as a whole. The two-polaron phase diagram exhibits two sharp transitions, leading to light dimers at strong coupling and the flattening of the dimer dispersion at some critical values of the parameters. This dimer (quasi)self-trapping occurs at coupling strengths where single polarons are mobile. This illustrates that, depending on the strength of the phonon-mediated interactions, the coupling to phonons may completely suppress or strongly enhance quantum transport of correlated particles.

[Analysis of Anti-VEGF Intravitreal Injection Treatment in Clinical Practice]. / Analyse der Durchführung der intravitrealen operativen Medikamenteneingabe im klinischen Alltag.

BACKGROUND: As AMD patients are very often administered intravitreal operative drugs (IVOM), the relevant procedure in ophthalmological institutes was examined in the present project: A questionnaire was used to collect data on structures, criteria and time expended in the treatment in single or small practices, clinics and (university) departments of ophthalmology. 42 facilities participated in the main study. RESULTS: The patient is usually given an appointment within two weeks of the first contact. If the patient has AMD requiring treatment, the first IVOM is administered within up to two weeks. This often lasts no longer than three hours. The follow-ups after the injection cycle may last up to one hour. If the findings are stable, there is normally a new follow-up after four weeks. The criterion for retreatment is always given as SD-OCT, followed by vision and funduscopy. The next appointment for injection is normally within one week. In diagnostic testing, angiography is almost as important as SD-OCT, funduscopy and vision, but is rarely used as a criterion for retreatment. The main differences in the organisation of the treatment plan are in the time course of the first IVOM and the follow-ups after the injection cycle. In this respect, practice clinics and individual or group practices may be quicker than departments of ophthalmology. One third of the surveyed facilities stated that they cooperated in diagnostic testing. These cooperating facilities repeat many investigations, both in diagnostic testing and in follow-ups. CONCLUSION: Bearing in mind that IVOM patients have a special interest in timely treatment, it would be desirable to shorten the waiting times, both for injection appointments and during treatment. Cooperation between the different service providers is sensible if this shortens the treatment pathways and relieve the patient and ophthalmologist. Moreover, both groups could benefit from standard and efficient treatment pathways, as these simplify patient care, increase the patient's satisfaction with the treatment and therefore tend to increase compliance.