Excitons and biexcitons in InGaN quantum dot like localization centers.

Indium segregation in a narrow InGaN single quantum well creates quantum dot (QD) like exciton localization centers. Cross-section transmission electron microscopy reveals varying shapes and lateral sizes in the range ∼1-5 nm of the QD-like features, while scanning near field optical microscopy demonstrates a highly inhomogeneous spatial distribution of optically active individual localization centers. Microphotoluminescence spectroscopy confirms the spectrally inhomogeneous distribution of localization centers, in which the exciton and the biexciton related emissions from single centers of varying geometry could be identified by means of excitation power dependencies. Interestingly, the biexciton binding energy (E(b)xx) was found to vary from center to center, between 3 to -22 meV, in correlation with the exciton emission energy. Negative binding energies are only justified by a three-dimensional quantum confinement, which confirms QD-like properties of the localization centers. The observed energy correlation is proposed to be understood as variations of the lateral extension of the confinement potential, which would yield smaller values of E(b)xx for reduced lateral extension and higher exciton emission energy. The proposed relation between lateral extension and E(b)xx is further supported by the exciton and the biexciton recombination lifetimes of a single QD, which suggest a lateral extension of merely ∼3 nm for a QD with strongly negative E(b)xx = -15.5 meV.

Early and long-term outcome after thoracic endovascular aortic repair (TEVAR) for acute complicated type B aortic dissection.

OBJECTIVES: The study aimed to investigate early and long-term outcome of thoracic endovascular aortic repair (TEVAR) for acute complicated type B dissection. DESIGN: This was a retrospective, single-centre, consecutive case series. MATERIALS AND METHODS: During the period 1999-2009, TEVAR was carried out in 50 patients with non-traumatic acute complicated type B dissection, and in another 10 patients with acute complications, including rupture, end-organ ischaemia and acute dilatation during the primary hospitalisation, but >14 days after onset of symptoms. Thus, in total, 60 patients were included; 22 with a DeBakey type IIIa dissection and 38 with a type IIIb; median age was 67 years. Early (30-day) and long-term (5-year) survival, re-intervention rate and complications were recorded until 1 July 2010. RESULTS: Within 30 days, two (3%) deaths, one (2%) paraplegia and three (5%) strokes were observed. Five-year survival was 87% and freedom from re-intervention at 5 years was 65%. CONCLUSIONS: In patients with acute complicated type B aortic dissection, TEVAR can be performed with excellent early and long-term survival, whereas morbidity and long-term durability must be further elucidated.

Intravascular ultrasound with a vector phased-array probe (AcuNav) is feasible in endovascular abdominal aortic aneurysm repair.

BACKGROUND: The ideal imaging method for endovascular aneurysm repair (EVAR) should provide all data regarding diagnosis, measurements, and guiding of stent-graft deployment. Contrast-enhanced computed tomography (CT) is used for preoperative EVAR planning, together with intraoperative angiography. However, the administered contrast volume might result in contrast-induced nephropathy (CIN). PURPOSE: To develop a technique for aortic measurements, vessel wall evaluation, and stent-graft positioning by using a vector phased-array intravascular ultrasound probe with color Doppler function (AcuNav) in elective EVAR. MATERIAL AND METHODS: Thirteen elective EVAR patients were included. AcuNav was compared to pre- and postoperative CT examinations, perioperative angiography, and postoperative duplex. RESULTS: Measurements for stent-graft sizing were easily obtained and facilitated by the color Doppler function and corresponded well with CT and angiography. The combined information from AcuNav and fluoroscopy provided exact positioning of the stent graft. An aortic placement of the probe provided superior imaging results compared to an inferior vena cava approach. Detection of endoleak was found to be difficult. No complications were registered. CONCLUSION: The use of AcuNav combined with fluoroscopy in EVAR was found to be safe, effective, and feasible in planning and guiding EVAR procedures. Best results were seen with the probe placed in the artery. AcuNav might be used to replace contrast-enhanced CT and angiography, hence reducing the risk of CIN, especially in high-risk patients.

The future of imaging in the management of abdominal aortic aneurysm.

The development of endovascular techniques depends on the concomitant development of imaging techniques. Imaging with ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MR) is evolving at rapid pace. Angiography has largely been replaced by these techniques as a diagnostic tool in the clinical setting. New methods, e.g., rotational angiography and intravascular ultrasound, will play an important role in endovascular treatment of vascular disease. It is necessary to have easy access to ultrasonography, CT and MR images in future hybrid angiographic/surgical suites and the operator must be able to do advanced immediate reconstructions in a sterile environment. The combined use of advanced imaging, open and endovascular techniques will further improve the treatment of vascular disease in the future.

Propositions for refinement of the hybrid surgical technique for treatment of thoraco-abdominal aortic aneurysm.

Traditional open repair of thoraco-abdominal aortic aneurysms Crawford type II-IV carries a high perioperative risk and mortality. The hybrid technique for combined surgical and endovascular treatment offers an interesting alternative with reduced risk of paraparesis and possibly a reduced mortality rate. Propositions for refinement of this approach are outlined based on a single centre experience.

Palmoplantar pustulosis: a clinical and immunohistological study.

Pustulosis palmoplantaris (PPP) is a common chronic skin disease, which is very resistant to treatment. It is not known why the lesions are located in the palms and soles. There are few studies of the disease and in particular studies of the histology. Fifty-nine patients with PPP answered a questionnaire concerning their medical history and 39 of them were clinically examined. Biopsy specimens were taken from involved skin in 22 of the 39 patients and studied immunohistologically for tryptase+ mast cells, EG2+ eosinophils, lipocalin+ neutrophils and CD3+ T lymphocytes. The sweat gland and sweat duct were visualized with AE1/AE3 antibody (cytokeratins 1-8, 10, 14/15, 16, 19). In addition to neutrophils in the pustule and lymphocytes in the upper dermis, there were also large numbers of mast cells and eosinophils in the subpustular area. Numerous eosinophils were present in the pustule. The epidermal part of the eccrine duct was not detectable in any of the specimens from patients with PPP but was present in all of the nine control persons (including two smokers). The results indicate that the acrosyringium is involved in the inflammation and also that mast cells and eosinophils participate in a hitherto unknown way. Of the 39 patients clinically examined, two had previously diagnosed thyroid disease and two had gluten hypersensitivity. Seventeen had one or several abnormal serum concentrations of thyroid-stimulating hormone, thyroxin, antibodies against thyroglobulin or thyroperoxidase and 10 had immunoglobulin (Ig) A antibodies to gliadin. The mean +/- SD for serum IgA and for eosinophil cationic protein was increased. From the questionnaire the most notable finding was that 56 of the 59 patients had been or still were smokers, all of whom had started smoking before the first signs of PPP. We hypothesize that the acrosyringium might be the target for the inflammation and that PPP is linked to autoimmune thyroid disease and smoking.

Metal contents in liver tissues of non-fledged goldeneye, Bucephala clangula, ducklings: a comparison between samples from acidic, circumneutral, and limed lakes in south Sweden.

The risk of increased exposure to metals for a vertebrate predator foraging on aquatic insects in acidified lakes was investigated through analyses of the content of Al, As, Ca, Cd, Cu, Fe, Hg, Mn, Pb, Ru, Se, and Zn in the liver tissue of 42 non-fledged Goldeneye, Bucephala clangula, ducklings from acidic, circumneutral, and limed lakes in South Sweden. No indications of significantly different concentrations in samples from acidic lakes in comparison with circumneutral lakes were detected for any metal, but among individual birds from acidic lakes there were high contents of Hg. Liming probably affects the exposure to some metals; lower contents of Hg were recorded from limed lakes in comparison with acidic lakes, while the reverse trend was recorded for Cd and Mn.