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GaAs nanomembranes grown by selective area epitaxy are novel structures. The high refractive index of GaAs makes them good candidates for nanoantennas. We numerically studied the optical modal structure of the resonator. The nanomembrane geometry introduces a strong light-polarization dependence. The scattering is dominated by an electric dipole contribution for polarization along the nanomembrane long dimension and by a magnetic dipole contribution in the orthogonal direction. The dependence on the geometry of the resonances close to the GaAs band gap was modeled by a single coefficient. It describes the resonance shifts against up-to 40% changes in length, height, and width. We showed that the nanomembranes exhibited field enhancement, far-field directionality, and tunability with the GaAs band gap. All these elements confirm their great potential as nanoantennas.

Objectives: The aim of this study was to analyse outcomes over 2 decades using cryopreserved vascular allografts to treat vascular infection. Methods: We conducted a retrospective study of patients identified from our institutional database who were treated for primary or secondary vascular infection using implanted allografts. Results: Between October 1992 and May 2014, 54 patients underwent surgery for vascular infection out of 118 patients implanted with cryopreserved vascular allografts. The 52 patients for whom we had full information form the basis of the study with a 96% follow-up. The average age was 64 ± 11 years ; 87% were men ; 65% had previous vascular surgery ; 19% had emergency operations. A total of 75% of the patients had aortoiliofemoral infections. Five patients underwent surgery with cardiopulmonary bypass. Fifty percent required more than 1 allograft and 15% had concomitant procedures. Seventy-three percent (38/52) of specimen cultures yielded positive results with polymicrobial flora in 29%. Surgical specimens most frequently grew coagulase-negative staphylococci. The early postoperative reoperation rate was 15% for allograft- related complications. There were 20 (38%) early deaths, including deaths of acute myocardial infarction, anastomosis rupture and persistent sepsis and shock. Uncontrolled infection leading to septic shock and multiple organ failure was the cause of death in 50% of the cases. The mean duration of freedom from allograft reintervention was 12.2 years. The mean duration of freedom from allograft occlusion or limb loss was 12.1 years [95% confidence interval (CI) 9.9-14.4]. Of the 32 surviving patients, we had patency information for 66% obtained by angiography or computed tomography. The mean survival for the cohort was 5.9 years (95% CI 3.9-7.8). Mean freedom from cardiovascular infection-related death was 9.3 years (95% CI 7.2- 11.4). Conclusions: Allografts can be indicated for treatment of primary/secondary infection and have remarkable results in multimorbid patients. Patients with vascular infection have a high-risk profile, around 40% mortality during the first 6 months, with reduction in overall mortality thereafter. We believe that allografts may play a role in the surgical treatment of vascular infection.

The aim of this in vivo study was to compare the efficacy of vancomycin at standard doses (VAN-SD) to that of VAN at adjusted doses (VAN-AD) in achieving a VAN area under the curve/MIC ratio (AUC/MIC) of ≥400 against three methicillin-resistant Staphylococcus aureus (MRSA) strains with different microdilution VAN MICs in an experimental endocarditis model. The valve vegetation bacterial counts after 48 h of VAN therapy were compared, and no differences were observed between the two treatment groups for any of the three strains tested. Overall, for VAN-SD and VAN-AD, the rates of sterile vegetations were 15/45 (33.3%) and 21/49 (42.8%) ( P = 0.343), while the medians (interquartile ranges [IQRs]) for log 10 CFU/g of vegetation were 2 (0 to 6.9) and 2 (0 to 4.5) ( P = 0.384), respectively. In conclusion, this VAN AUC/MIC pharmacodynamic target was not a good predictor of vancomycin efficacy in MRSA experimental endocarditis.

The growth mechanism of stacked InAs/InP(001) quantum wires (QWRs) is studied by combining an atomic-scale cross-sectional scanning tunnelling microscopy analysis with in situ and in real-time stress measurements along the [110] direction (sensitive to stress relaxation during QWR formation). QWRs in stacked layers grow by a non-Stranski–Krastanov (SK) process which involves the production of extra InAs by strain-enhanced As/P exchange and a strong strain driven mass transport. Despite the different growth mechanism of the QWR between the first and following layers of the stack, the QWRs maintain on average the same shape and composition in all the layers of the stack, revealing the high stability of this QWR configuration., This work has been supported by the European Union through the SANDiE Network of Excellence (contract No. NMP4-CT-2004-500101). The authors also acknowledge financial support by the Spanish MEC and CAM through projects TEC-2005-05781-C03-01, NAN2004-09109-C04-01, Consolider QOIT CSD2006-0019 and S-505/ESP/000200.

We have studied the optical properties of InAs site-controlled quantum dots (SCQDs) grown on pre-patterned GaAs substrates. Since InAs nucleates preferentially on the lithography motifs, the location of the resulting QDs is determined by the pattern, which is fabricated by local oxidation nanolithography. Optical characterization has been performed on such SCQDs to study the fundamental and excited states. At the ground state different exciton complex transitions of about 500 μeV linewidth have been identified and the fine structure splitting of the neutral exciton has been determined (≈65 μeV). The observed electronic structure covers the demands of future quantum information technologies. © 2013 AIP Publishing LLC., The authors want to acknowledge the financial support from Spanish government through grants QD-NANOTICS: TEC2011-29120-C05-01, EPIC-NANOTICS: TEC2011-29120-C05-04, PROMESA: ENE2012-37804-C02-02, and Q&C Light: S2009ESP-1503. We also thank the support from the PROMETEO 2009/74 project (Generalitat Valenciana). J.C.-F. thanks the Spanish MCI for his FPI grant (No. BES-2006-12300) and J.H. acknowledges to the JAE program for the funds.

We report compelling evidence for a >gray> condensate of dipolar excitons, electrically polarised in a 25 nm wide GaAs quantum well. The condensate is composed by a macroscopic population of dark excitons coherently coupled to a lower population of bright excitons. To create the exciton condensate we use an all-optical approach in order to produce microscopic traps which confine a dense exciton gas (~ 1010 cm-2) that yet exhibits an anomalously weak photoemission at sub-kelvin temperatures. This is the first fingerprint for the >gray> condensate. It is then confirmed by the macroscopic spatial coherence and the linear polarization of the weak excitonic photoluminescence emitted from the trap, as theoretically predicted. Copyright © EPLA, 2014., This work has been supported by the European projects (EU) ITN-INDEX, EU-CIG XBEC, EU-ERC OSYRIS, EU-IP SIQS, EU-STREP EQUAM, by the Spanish MINECO (Grant TEC2011-29120-C05-04), CAM (Grant S2009ESP-1503).

4 figuras, 4 páginas.-- PACS number(s): 78.67.Hc, 73.21.La, 78.55.Cr, We investigate the electronic and optical properties of InAs double quantum dots grown on GaAs (001) and laterally aligned along the [110] crystal direction. The emission spectrum has been investigated as a function of a lateral electric field applied along the quantum dot pair mutual axis. The number of confined electrons can be controlled with the external bias, leading to sharp energy shifts which we use to identify the emission from neutral and charged exciton complexes. Quantum tunneling of these electrons is proposed to explain the reversed ordering of the trion emission lines as compared to that of excitons in our system., The authors wish to acknowledge to Spanish MICINN through projects Consolider-Ingenio 2010 QOIT (CSD2006-0019), TEC2008-06756-C03-01/03, and CTQ2008-03344, and to Comunidad Autónoma de Madrid through project Q&CLight (S2009ESP-1503).

This article is distributed under the terms of the Creative Commons Attribution Noncommercial License.-- This article is part of the series 8th International Workshop on Epitaxial Semiconductors on Patterned Substrates and Novel Index Surfaces., In this work, we present results on the formation of vertical molecule structures formed by two vertically aligned InAs quantum dots (QD) in which a deliberate control of energy emission is achieved. The emission energy of the first layer of QD forming the molecule can be tuned by the deposition of controlled amounts of InAs at a nanohole template formed by GaAs droplet epitaxy. The QD of the second layer are formed directly on top of the buried ones by a strain-driven process. In this way, either symmetric or asymmetric vertically coupled structures can be obtained. As a characteristic when using a droplet epitaxy patterning process, the density of quantum dot molecules finally obtained is low enough (2 × 108 cm−2) to permit their integration as active elements in advanced photonic devices where spectroscopic studies at the single nanostructure level are required., The authors wish to acknowledge to Spanish MICINN through projects Consolider-Ingenio 2010 QOIT (CSD2006-0019) and IMAGINE (CSD2009-00013), NANINPHO-QD (TEC2008-06756-C03-01/03 and 02), the Junta de Andalucía (PAI research group TEP-120 and project P08-TEP-03516) and CAM 2010 Q&CLight (S2009ESP-1503).

Evolution of the size, shape and composition of self-assembled InAs/InP quantum wires through the Stranski–Krastanov transition has been determined by aberration-corrected Z-contrast imaging. High resolution compositional maps of the wires in the initial, intermediate and final formation stages are presented. (001) is the main facet at their very initial stage of formation, which is gradually reduced in favour of {114} or {118}, ending with the formation of mature quantum wires with {114} facets. Significant changes in wire dimensions are measured when varying slightly the amount of InAs deposited. These results are used as input parameters to build three-dimensional models that allow calculation of the strain energy during the quantum wire formation process. The observed morphological evolution is explained in terms of the calculated elastic energy changes at the growth front. Regions of the wetting layer close to the nanostructure perimeters have higher strain energy, causing migration of As atoms towards the quantum wire terraces, where the structure is partially relaxed; the thickness of the wetting layer is reduced in these zones and the island height increases until the (001) facet is removed., This work was supported by the Spanish MCI (TEC2008-06756-C03-02 and 03, Consolider-Ingenio 2010 IMAGINE CSD2009-00013 and QOIT CSD2006-0019), the Junta de Andalucia (PAI research groups TEP-120 and TIC-145; project P08-TEP-03516), the CAM (Q&CLight S2009ESP-1503) and the Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, US DOE (MV and SJP).

Trabajo presentado a la "11th International Conference on Optics of Excitons in Confined Systems" (OECS), celebrada en en Madrid (España) del 7 al 11 de Septiembre de 2009., We have studied the lateral coupling between InAs/GaAs quantum dot pairs embedded in a field-effect structure. Quantum dot pairs and molecules have been identified by the correlated evolution of the Coulomb blockade features of each QD in the pair. This behaviour is largely distorted in the presence of resonant coupling states in the QD molecule. Single QD voltage evolution shows a crossover in the lineshape profile, which is associated to Spectral Diffusion processes due to residual charged environment., The authors gratefully acknowledge financial support by Spanish Ministry of Science and Innovation through grants NANINPHO-QD (TEC-2008-06756-C03-01/03) and Consolider-Ingenio 2010 QOIT(CSD2006-0019) and CAM (S-505/ESP/000200).

To manufacture improved nanostructures for telecommunication devices which respond to increasing requirements of data transmission speed and stability, the self-assembly process is an interesting approach to be followed. In this context, the control of the morphology, position, composition and strain of the nano-objects constituting these nanostructures is a crucial factor to improve their functionality [1]. It is well known that, during the growth of stacked layers, the upper nano-objects are strongly influenced by the distribution and intensity of the heterogeneous strain field caused by the ones underneath. Key aspects such as substrate temperature and spacer layer thickness between layers alter the strain field at the growth surface and therefore the nucleation sites of the stacked nano-objects.

http://link.aip.org/link/?JAPIAU/103/056108/1, We demonstrated the effect of reactive ion beam etching (RIBE) process on the PL properties of CdTe/sapphire metal organic vapor phase epitaxy layers. At optimum conditions, the RIBE attack does not make significant morphological changes but it results in an increase of the concentration of acceptor impurities. This was revealed by an increase of the overall photoluminescence (PL) intensity and, simultaneously, a decrease of the PL decay time, more important on the low energy side of PL spectrum due to the recombination of carriers in acceptor pairs., This work was supported by the Spanish projects TEC-2005-05781-C03-03 and CAM SENSORCDT S-0505/MAT/0209.

Póster presentado a la Reunión Anual de la Sociedad Óptica Europea celebrada en Paris (Francia) en 2008.

We present a study of the structural and optical properties of InAs quantum dots formed in a low density template of nanoholes fabricated by droplet epitaxy on GaAs (001). The growth conditions used here promote the formation of isolated quantum dots only inside the templated nanoholes. Due to the good optical quality and low density of these nanostructures, their ensemble and individual emission properties could be investigated and related to the particular growth method employed and the quantum dot morphology., The authors gratefully acknowledge the financial support by the Spanish MEC and CAM through project Nos. TEC-2005-05781-C03-01/-03 and NAN2004-09109-C04-01/-03, by the Consolider-Ingenio 2010 CSD2006-0019 and S-505/ESP/000200, and by the European Commission through SANDIE Network of Excellence No. NMP4-CT-2004- 500101 . P.A.G. thanks the I3P program.

This work presents a selective ultraviolet (UV)-ozone oxidation-chemical etching process that has been used, in combination with laser interference lithography (LIL), for the preparation of GaAs patterned substrates. Further molecular beam epitaxy (MBE) growth of InAs results in ordered InAs/GaAs quantum dot (QD) arrays with high optical quality from the first layer of QDs formed on the patterned substrate. The main result is the development of a patterning technology that allows the engineering of customized geometrical displays of QDs with the same optical quality as those formed spontaneously on flat non-patterned substrates. The authors gratefully acknowledge financial support from the Spanish MEC and CAM through projects nos TEC-2005-05781-C03-01, NAN2004-09109-C04-01, Consolider-Ingenio 2010 CSD2006-0019 and S-505/ESP/000200, and from the European Commission through the SANDIE Network of Excellence (no. NMP4-CT-2004-500101). PAG and JMS thank the I3P program. Mr H Kelderman of the MESA+research institute is gratefully acknowledged for production of the LIL patterns.

6 páginas, 4 figuras, 1 tabla.-- PACS: 42.55.Px; 73.21.Cd; 73.21.Hb., Waveguides formed by (InP)5/(Ga0.47In0.53As)4 short-period superlattices (SPSL) have been grown and characterized for their use as waveguides in InAs self-assembled quantum wires (QWR) lasers. Atomic force microscopy has been used to characterize both the SPSL and the QWR morphology quality. It is demonstrated that the shape of the QWR strongly depends on the roughness of the SPSL surface and that an atomically flat surface is necessary to obtain a uniform QWR size and shape morphology. Photoluminescence (PL) spectroscopy is also employed as a feedback to achieve the optimum growth parameters in order to obtain high-quality QWR confined by SPSL., This work was financed by Spanish projects MEC TEC- 2005-05781-C03-01, CONSOLIDER-Ingenio 2010 QOIT CSD2006-0019 and CAM S_0505ESP_0200, and by UE SANDIE Network of excellence (Contract no. NMP4-CT- 2004-500101).

We present a Raman study of the vibrational modes in InAs/InP (001) quantum wires. The energy of the observed phonon modes evidences the confinement properties of the wires, their strain anisotropy and the effect of atomic intermixing. Resonance effects in confined and interface phonons are discussed for excitation in the vicinity of the E1 critical point. The observed vibrations and their variation with sample characteristics are in agreement with the conclusions of previous structural and optical characterization performed in the same samples. © 2007 American Institute of Physics.

This study was performed to determine the value of dipyridamole-99 mTc-methoxy-isobutyl isonitrile perfusion (99mTC-MIBI) tomographic scintigraphy in the assessment of cardiac risk in patients being evaluated prior to combined pancreas-kidney transplantation (PKT). We performed perfusion tomographic scintigraphy using single photon emission computed tomography (SPECT) on 77 patients. The tomographic images did not show clinically relevant findings in 65 patients. In the remaining 12 patients, coronary arteriography was performed: 2 showed normal results, 4 showed no stenosis, and 6 showed significant stenosis (≥ 70%). Seventy-two patients underwent PKT. During the follow-up (6–48 months), there were seven cardiac events, 4 patients with significant stenosis, and 3 with nonsignificant stenosis upon coronary arteriography, and all had pathological tomographic images. 99mTc-MIBI tomographic scintigraphy may be useful in identifying patients at low risk of incurring cardiac events after PKT and may, in a large group of patients, obviate the need for routine coronary angiography.

Esophageal cancer is characterized by an overall poor prognosis. Due to late onset of symptoms and early metastatic spread, only about 15–20% of patients undergo curative resection [1]. Accurate staging in esophageal squamous cell carcinoma (SCC) is essential to decide the correct therapeutic strategy. Currently, a limited number of patients are candidates for curative resection while in those with advanced-stage disease a combination of neoadjuvant chemotherapy and/or radiotherapy followed by surgery is recommended.