Lasing mode pattern of a quantum cascade photonic crystal surface-emitting microcavity laser

The identification of the lasing mode within a quantum cascade photonic crystal microcavity laser emitting at λ ~8 µm is presented. The symmetry of the lasing mode is determined by the position of nodal lines within micro-bolometer camera measurements of its polarized spatial distribution. Full three-dimensional finite-difference time-domain simulations are also performed, and the resulting vertically emitted radiation field pattern is seen to follow the experimental results closely

Flood hazard of major river segments, Benevento Province, Southern Italy

On 15 October 2015, a storm-induced flood hit the central sector of Benevento Province (southern Italy) causing two deaths and severe damage to infrastructure, buildings and local agriculture. This area has a long history of similar events and since 1924 its major river segments have been monitored with several hydrometric stations. We used data from two of these stations and a LiDAR derived high-resolution topography to develop a flood hazard map. For map computation, we first derived a flood inundation map from topography. Subsequently we estimated the probability of exceedance of each specific fluvial stage from the combination of a Generalized Extreme Value and a Gamma fits of available hydrometric data. As boundary condition, we considered a reference scenario corresponding to an estimated 500 year flood. The hazard maps provide an overview of the flood hazard in the central sector of Benevento Province and floodplains zonation in flood perspective

Endoscopic management of patients with post-surgical leaks involving the gastrointestinal tract: a large case series

Background: Post-surgical anastomotic leaks often require a re-intervention, are associated with a definite morbidity and mortality, and with relevant costs. We described a large series of patients with different post-surgical leaks involving the gastrointestinal tract managed with endoscopy as initial approach. Methods: This was a retrospective analysis of prospectively collected cases with anastomotic leaks managed with different endoscopic approaches (with surgical or radiological drainage when needed) in two endoscopic centres during 5 years. Interventions included: (1) over-the-scope clip (OTSC) positioning; (2) placement of a covered self-expanding metal stent (SEMS); (3) fibrin glue injection (Tissucol); and (4) endo-sponge application, according to both the endoscopic feature and patient’s status. Results: A total of 76 patients underwent endoscopic treatment for a leak either in the upper (47 cases) or lower (29 cases) gastrointestinal tract, and the approach was successful in 39 (83%) and 22 (75.9%) patients, respectively, accounting for an overall 80.3% success rate. Leak closure was achieved in 84.9% and 78.3% of patients managed by using a single or a combination of endoscopic devices. Overall, leak closure failed in 15 (19.7%) patients, and the surgical approach was successful in all 14 patients who underwent re-intervention, whilst one patient died due to sepsis at 7 days. Conclusions: Our data suggest that an endoscopic approach, with surgical or radiological drainage when needed, is successful and safe in the majority of patients with anastomotic gastrointestinal leaks. Therefore, an endoscopic treatment could be attempted before resorting to more invasive, costly and risky re-intervention

Endoscopic management of patients with post-surgical leaks involving the gastrointestinal tract: a large case series

Background: Post-surgical anastomotic leaks often require a re-intervention, are associated with a definite morbidity and mortality, and with relevant costs. We described a large series of patients with different post-surgical leaks involving the gastrointestinal tract managed with endoscopy as initial approach. Methods: This was a retrospective analysis of prospectively collected cases with anastomotic leaks managed with different endoscopic approaches (with surgical or radiological drainage when needed) in two endoscopic centres during 5 years. Interventions included: (1) over-the-scope clip (OTSC) positioning; (2) placement of a covered self-expanding metal stent (SEMS); (3) fibrin glue injection (Tissucol); and (4) endo-sponge application, according to both the endoscopic feature and patient’s status. Results: A total of 76 patients underwent endoscopic treatment for a leak either in the upper (47 cases) or lower (29 cases) gastrointestinal tract, and the approach was successful in 39 (83%) and 22 (75.9%) patients, respectively, accounting for an overall 80.3% success rate. Leak closure was achieved in 84.9% and 78.3% of patients managed by using a single or a combination of endoscopic devices. Overall, leak closure failed in 15 (19.7%) patients, and the surgical approach was successful in all 14 patients who underwent re-intervention, whilst one patient died due to sepsis at 7 days. Conclusions: Our data suggest that an endoscopic approach, with surgical or radiological drainage when needed, is successful and safe in the majority of patients with anastomotic gastrointestinal leaks. Therefore, an endoscopic treatment could be attempted before resorting to more invasive, costly and risky re-intervention

Quantum Cascade Surface-Emitting Photonic Crystal Laser

We combine photonic and electronic band structure engineering to create a surface-emitting quantum cascade microcavity laser. A high-index contrast two-dimensional photonic crystal is used to form a micro-resonator that simultaneously provides feedback for laser action and diffracts light vertically from the surface of the semiconductor surface. A top metallic contact allows electrical current injection and provides vertical optical confinement through a bound surface plasmon wave. The miniaturization and tailorable emission properties of this design are potentially important for sensing applications, while electrical pumping can allow new studies of photonic crystal and surface plasmon structures in nonlinear and near-field optics

Quantum cascade photonic-crystal microlasers

We describe the realization of Quantum Cascade photonic-crystal microlasers. Photonic and electronic bandstructure engineering are combined to create a novel Quantum Cascade microcavity laser source. A high-index contrast two-dimensional photonic crystal forms a micro-resonator that provides feedback for laser action and diffracts light vertically from the surface of the semiconductor chip. A top metallic contact is used to form both a conductive path for current injection as well as to provide vertical optical confinement to the active region through a bound surface plasmon state at the metal-semiconductor interface. The device is miniaturized compared to standard Quantum Cascade technology, and the emission properties can in principle be engineered by design of the photonic crystal lattice. The combination of size reduction, vertical emission, and lithographic tailorability of the emission properties enabled by the use of a high-index contrast photonic crystal resonant cavity makes possible a number of active sensing applications in the mid- and far-infrared. In addition, the use of electrical pumping in these devices opens up another dimension of control for fundamental studies of photonic crystal and surface plasmon structures in linear, non-linear, and near-field optics

Molecular Epidemiology and Virulence Profiles of Colistin-Resistant Klebsiella pneumoniae Blood Isolates From the Hospital Agency “Ospedale dei Colli,” Naples, Italy

Resistance to colistin is increasingly reported in Klebsiella pneumoniae clinical isolates. The aim of this study was to analyze the molecular epidemiology and virulence profiles of 25 colistin-resistant K. pneumoniae blood isolates from the Hospital Agency “Ospedale dei Colli,” Naples, Italy, during 2015 and 2016. Colistin MIC values of isolates ranged from 4 to 256 mg/L. The inactivation of the mgrB gene, encoding a negative regulator of the PhoQ/PhoP signaling system, was the most frequent mechanism of colistin resistance found in 22 out of 25 isolates. Of these, 10 isolates assigned to ST512 and PFGE types A and A4 showed identical frameshift mutation and premature termination of mgrB gene; 4 isolates assigned to ST258 and PFGE types A1 showed non-sense, frameshift mutation, and premature termination; 3 and 1 isolates assigned to ST258 and PFGE A2 and ST512 and PFGE A3, respectively, had insertional inactivation of mgrB gene due to IS5-like mobile element; 2 isolates assigned to ST101 and 1 to ST392 had missense mutations in the mgrB gene, 1 isolate assigned to ST45 showed insertional inactivation of mgrB gene due to IS903-like mobile element. phoQ missense mutations were found in 2 isolates assigned to ST629 and ST101, respectively, which also showed a missense mutation in pmrA gene. The mcr-1-2-3-4 genes were not detected in any isolate. Colistin-resistant K. pneumoniae isolates showed variable virulence profiles in Galleria mellonella infection assays, with the infectivity of two isolates assigned to ST45 and ST629 being significantly higher than that of all other strains (P < 0.001). Interestingly, colistin MIC values proved to make a significant contribution at predicting lethal doses values (LD50 and LD90) of studied isolates in G. mellonella. Our data show that MgrB inactivation is a common mechanism of colistin resistance among K. pneumoniae in our clinical setting. The presence of identical mutations/insertions in isolates of the same ST and PFGE profile suggests the occurrence of clonal expansion and cross-transmission. Although virulence profiles differ among isolates irrespective of their genotypes, our results suggest that high colistin MIC could predict lower infectivity capability of the isolates

Influence of Chemical Composition and Microvesiculation on the Chromatic Features of the Obsidian of Sierra de las Navajas (Hidalgo, Mexico)

The obsidian of Sierra de las Navajas is well known for its green color and gold hue. In order to relate these features with compositional and microtextural characteristics, we have carried out a microanalytical study by Wave Dispersion System associated to Electron Probe Micro-Analyzer, Scanning Electron Microscope observation, and X-rays micro-tomographic analyses of samples showing different colors (dark to light green, sometimes with bands of different color intensity) and hues (changing, uniform, no hue). In accordance with previous studies, the green color of the obsidian seems to be related to a high iron content, probably in its reduced state. However, no significant difference in composition occurs between dark and light green samples. The SEM observation and microtomographic study revealed the absence of microcrystals and the occurrence of vesicles of different size, shape, and orientation. Lighter green colors are shown by highly vesiculated surfaces, whereas non-vesiculated samples are darker. On the surfaces with a high concentration of coarse vesicles, a uniform golden hue is observed. Decreasing vesiculation gives a hue changing with the angle of incident light. However, when the vesicularity approaches zero, no hue is visible. The iso-orientation of vesicles along preferential directions and their distribution in bands determine the variation in color intensity and hue on differently oriented surfaces. Microvesiculation also influences other characteristics that were important features for the use of obsidian in the past, such as fracture, transparency, and roughness

Clinically relevant increases in serum neurofilament light chain and glial fibrillary acidic protein in patients with Susac syndrome

Background and purpose: Serum levels of neurofilament light chain (sNfL) and glial fibrillary acidic protein (sGFAP) are promising neuro-axonal damage and astrocytic activation biomarkers. Susac syndrome (SS) is an increasingly recognized neurological condition and biomarkers that can help assess and monitor disease evolution are highly needed for the adequate management of these patients. sNfL and sGFAP levels were evaluated in patients with SS and their clinical relevance in the relapse and remission phase of the disease was assessed. Methods: As part of a multicentre study that enrolled patients diagnosed with SS from six international centres, sNfL and sGFAP levels were assessed in 22 SS patients (nine during a relapse and 13 in remission) and 59 age- and sex-matched healthy controls using SimoaTM assay Neurology 2-Plex B Kit. Results: Serum NfL levels were higher than those of healthy controls (p < 0.001) in SS patients and in both subgroups of patients in relapse and in remission (p < 0.001 for both), with significantly higher levels in relapse than in remission (p = 0.008). sNfL levels showed a negative correlation with time from the last relapse (r = -0.663; p = 0.001). sGFAP levels were slightly higher in the whole group of patients than in healthy controls (p = 0.046) and were more pronounced in relapse than in remission (p = 0.013). Conclusion: In SS patients, both sNFL and sGFAP levels increased compared with healthy controls. Both biomarkers had higher levels during clinical relapse and much lower levels in remission. sNFL was shown to be time sensitive to clinical changes and can be useful to monitor neuro-axonal damage in SS