Cavity soliton inhibition of extreme events in lasers with injection.

Vortex mediated turbulence can be the key element in the generation of extreme events in spatially extended lasers with optical injection. Here, we study the interplay of vortex mediated turbulence and cavity solitons on the onset of extreme events in semiconductor lasers with injection. We first analyze and characterize these two features separately, spatiotemporal chaotic optical vortices for low values of the injection intensity and cavity solitons above the locking regime. In regimes where vortex mediated turbulence and cavity solitons coexist, localized peaks of light inhibit instead of enhancing the generation of rogue waves by locally regularizing the otherwise chaotic phase of the optical field. Cavity solitons can then be used to manipulate and control extreme events in systems displaying vortex mediated turbulence.

Unifying Frequency Combs in Active and Passive Cavities: Temporal Solitons in Externally Driven Ring Lasers.

Frequency combs have become a prominent research area in optics. Of particular interest as integrated comb technology are chip-scale sources, such as semiconductor lasers and microresonators, which consist of resonators embedding a nonlinear medium either with or without population inversion. Such active and passive cavities were so far treated distinctly. Here we propose a formal unification by introducing a general equation that describes both types of cavities. The equation also captures the physics of a hybrid device-a semiconductor ring laser with an external optical drive-in which we show the existence of temporal solitons, previously identified only in microresonators, thanks to symmetry breaking and self-localization phenomena typical of spatially extended dissipative systems.

From the Lugiato-Lefever equation to microresonator-based soliton Kerr frequency combs.

The model, that is usually called the Lugiato-Lefever equation (LLE), was introduced in 1987 with the aim of providing a paradigm for dissipative structure and pattern formation in nonlinear optics. This model, describing a driven, detuned and damped nonlinear Schroedinger equation, gives rise to dissipative spatial and temporal solitons. Recently, the rather idealized conditions, assumed in the LLE, have materialized in the form of continuous wave driven optical microresonators, with the discovery of temporal dissipative Kerr solitons (DKS). These experiments have revealed that the LLE is a perfect and exact description of Kerr frequency combs-first observed in 2007, i.e. 20 years after the original formulation of the LLE-and in particular describe soliton states. Observed to spontaneously form in Kerr frequency combs in crystalline microresonators in 2013, such DKS are preferred state of operation, offering coherent and broadband optical frequency combs, whose bandwidth can be extended exploiting soliton-induced broadening phenomena. Combined with the ability to miniaturize and integrate on-chip, microresonator-based soliton Kerr frequency combs have already found applications in self-referenced frequency combs, dual-comb spectroscopy, frequency synthesis, low noise microwave generation, laser frequency ranging, and astrophysical spectrometer calibration, and have the potential to make comb technology ubiquitous. As such, pattern formation in driven, dissipative nonlinear optical systems is becoming the central Physics of soliton micro-comb technology.This article is part of the theme issue 'Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 2)'.

Dissipative Phase Solitons in Semiconductor Lasers.

We experimentally demonstrate the existence of nondispersive solitary waves associated with a 2π phase rotation in a strongly multimode ring semiconductor laser with coherent forcing. Similarly to Bloch domain walls, such structures host a chiral charge. The numerical simulations based on a set of effective Maxwell-Bloch equations support the experimental evidence that only one sign of chiral charge is stable, which strongly affects the motion of the phase solitons. Furthermore, the reduction of the model to a modified Ginzburg-Landau equation with forcing demonstrates the generality of these phenomena and exposes the impact of the lack of parity symmetry in propagative optical systems.

A concomitant and complete set of nonvolatile all-optical logic gates based on hybrid spatial solitons.

We theoretically demonstrate the realization of a complete canonical set of all-optical logic gates (AND, OR, NOT), with a persistent (stored) output, by combining propagative spatial solitons in a photorefractive crystal and dissipative cavity solitons in a downstream broad-area vertical cavity surface emitting laser (VCSEL). The system uses same-color, optical-axis aligned input and output channels with fixed readout locations, while switching from one gate to another is achieved by simply varying the potential applied to the photorefractive crystal. The inputs are Gaussian beams launched in the photorefractive crystal and the output is a bistable, persistent soliton in the VCSEL with a 'robust' eye diagram and large signal-to-noise ratio (SNR). Fast switching and intrinsic parallelism suggest that high bit flow rates can be obtained.

Observation of electro-activated localized structures in broad area VCSELs.

We demonstrate experimentally the electro-activation of a localized optical structure in a coherently driven broad-area vertical-cavity surface-emitting laser (VCSEL) operated below threshold. Control is achieved by electro-optically steering a writing beam through a pre-programmable switch based on a photorefractive funnel waveguide.

Excimer laser technology in percutaneous coronary interventions: Cardiovascular laser society's position paper.

Excimer Laser Coronary Atherectomy (ELCA) is a well-established therapy that emerged for the treatment of peripheral vascular atherosclerosis in the late 1980s, at a time when catheters and materials were rudimentary and associated with the most serious complications. Refinements in catheter technology and the introduction of improved laser techniques have led to their effective use for the treatment of a wide spectrum of complex coronary lesions, such as thrombotic lesions, severe calcific lesions, non-crossable or non-expandable lesions, chronic occlusions, and stent under-expansion. The gradual introduction of high-energy strategies combined with the contrast infusion technique has enabled us to treat an increasing number of complex cases with a low rate of periprocedural complications. Currently, the use of the ELCA has also been demonstrated to be effective in acute coronary syndrome (ACS), especially in the context of large thrombotic lesions.

Difference differential equations for a resonator with a very thin nonlinear medium.

We derive from the classic Maxwell-Bloch equations a set of difference-differential equations valid, in general, when the length of the nonlinear medium in the optical cavity is much smaller than a wavelength. Such equations provide an elegant and simple framework in which the case of Fabry-Perot and ring cavity can be discussed in a unified way. We outline a complete scenario for the multimode laser instability in the Fabry-Perot case, illustrating the results for parameter values appropriate to quantum cascade lasers. Our approach can have a relevant impact also on the study of dynamical instabilities in external cavity semiconductor lasers, including multiple quantum well or quantum-dot structures.

Quality and in vitro fertilizing ability of cryopreserved cat spermatozoa obtained by urethral catheterization after medetomidine administration.

Quality and in vitro fertilizing ability of frozen-thawed cat semen collected by urethral catheterization (CT) or electroejaculation (EE) after medetomidine administration were compared. Sperm collection was performed by an urinary tomcat catheter and, 4 days apart, by electroejaculation from each of eight tomcats. Results showed that semen collected by CT was characterized by lower volume (10.5+/-5.3 microL, P<0.05), higher sperm concentration (1868.4+/-999.8 x 10(6)/mL, P<0.05) and lower pH (7.0+/-0.4, P<0.05) than that collected by EE (67.1+/-25.9 microL, 542.9+/-577.9 x 10(6)/mL, and 7.9+/-0.4, respectively). Spermatozoa characteristics after thawing at 0, 3 and 6h did not differ between the two methods of collection. Also cleavage rate and embryo production from oocytes fertilized with frozen-thawed spermatozoa collected by CT or EE showed no significant differences (P>0.05). In conclusion, the results obtained in the present study indicate that good quality freezable semen can be collected from cats by urethral catheterization after medetomidine administration. This new method of semen collection appears very useful in practice and, compared with the electroejaculation protocol, permits to obtain semen samples characterized by a higher concentration of spermatozoa, lower total volume and lower pH.

Gram-positive bloodstream infections in liver transplant recipients: incidence, risk factors, and impact on survival.

The objective of the study was to assess the incidence, risk factors, and survival of gram-positive bloodstream infections (GP-BSI(s)) among liver transplant recipients during the first year after transplantation. Between October 2000 and September 2006, 42 episodes of GP-BSI(s) occurred in 205 patients with an overall incidence of 0.20 episodes/patient. Coagulase-negative staphylococci were detected in 45.2% of cases, Enterococcus species in 42.9% (E faecalis, eight; E faecium, seven; E avium, two; E gallinarum, one) and Staphylococcus aureus in 11.9%. Retransplantation was the only independent risk factor for GP-BSI (odds ratio [OR], 0.253; 95% confidence interval (CI), 0.089 to 0.715; P = .009). Thirty-day mortality rate was 28.5% and S aureus infections were related to a poorer outcome. It is noteworthy that all the isolates of S aureus were methicillin-resistant. Ampicillin was inactive against all the strains of E faecium and 50% of E avium isolates, but active against all E faecalis and E gallinarum strains. All the isolates were glycopeptide-susceptible. No significant differences in mortality rate were observed in relation to sex, etiologies of end-stage liver disease, cytomegalovirus infection/reinfection, type of donor, rejection, or retransplantation. GP-BSI, the only independent risk factor for death (OR, 0.262; 95% CI, 0.106 to 0.643; P = .003), reduced the survival rate by 26% in the first year posttransplant. In conclusion, GP-BSI(s) impact significantly on morbidity and mortality posttransplant, particularly among retransplantations. Control measures are required to reduce the incidence of GP-BSI(s) in liver transplant recipients. These findings must be considered when empirical antimicrobial therapy is indicated while awaiting blood-culture results.

Effects of ketamine or medetomidine administration on quality of electroejaculated sperm and on sperm flow in the domestic cat.

The effects of two commonly used drugs for anaesthesia in the domestic cat, ketamine and medetomidine, on features of electroejaculated semen and on sperm flow in this species were evaluated performing three experiments. This is the first study about these topics in the domestic cat. In Experiment 1, ketamine or medetomidine effects on cat sperm quality after collection by electroejaculation (E.E.) have been assessed in nine animals. Results showed that mean sperm concentration was significantly higher (p<0.01) after medetomidine than after ketamine administration. In Experiment 2, ketamine or medetomidine effects on sperm flow in 12 electroejaculated cats were studied. Mean sperm concentration and mean total number of spermatozoa resulted significantly higher (p<0.01) in medetomidine than in ketamine treated animals. The number of spermatozoa displaced in urethra was significantly higher (p<0.01) using medetomidine. No significant differences were observed in percentages of retrograde flow. In Experiment 3, ketamine or medetomidine effects on urethral sperm flow, without any stimulation for sperm collection, were evaluated. Data obtained showed a significantly higher (p<0.05) number of spermatozoa displaced in urethra after medetomidine than after ketamine injection. In conclusion, E.E. in the cat after medetomidine administration determined a higher number of spermatozoa per ejaculate than after ketamine administration, with a good pharmacological restriction and without increasing sperm retrograde flow.

Refractory period of an excitable semiconductor laser with optical injection.

Injection-locked semiconductor lasers can be brought to a neuronlike excitable regime when parameters are set close to the unlocking transition. Here we study experimentally the response of this system to repeated optical perturbations and observe the existence of a refractory period during which perturbations are not able to elicit an excitable response. The results are analyzed via simulations of a set of dynamical equations which reproduced adequately the experimental results.

Publisher's Note: Refractory period of an excitable semiconductor laser with optical injection [Phys. Rev. E 95, 012214 (2017)].

This corrects the article DOI: 10.1103/PhysRevE.95.012214.

Characterization of antibody response in neuroinvasive infection caused by Toscana virus.

OBJECTIVES: Among sandfly-borne pathogens, Toscana virus (TOSV) is a prominent cause of summer meningitis in Mediterranean Europe. Here, we assessed the kinetics of anti-TOSV antibodies over time in 41 patients diagnosed with TOSV meningitis or meningoencephalitis in northeastern Italy. METHODS: Acute and follow-up serum samples were collected up to 20 months after diagnosis of TOSV infection and tested for the presence of specific antibody using immunoenzymatic and indirect immunofluorescence assays. In addition, maturation of anti-TOSV IgG over time was evaluated as well as production of neutralizing antibodies. RESULTS: Specific IgM and IgG response was present at diagnosis in 100% of patients; TOSV-specific IgM and IgG were detected in patients' sera up to 6 and 20 months after diagnosis, respectively. The avidity index (AI) increased over the first month after infection in 100% of patients and most cases exceeded 60% by Day 30 post infection. The AI subsequently plateaued then declined at 20 months after diagnosis. Finally, neutralization assay to TOSV was performed in 217 sera collected from 41 patients; 69.6% of tested samples resulted in reactive and moderate levels of neutralizing antibodies observed during all phases of infection despite high titres of total anti-TOSV IgG. CONCLUSIONS: Specific antibody response develops rapidly and is long-lasting for neuroinvasive TOSV infection. Serodiagnosis of neuroinvasive TOSV requires simultaneous detection of specific IgM and IgG. Moderate levels of neutralizing antibodies were maintained over the study period, while the protective role of antibodies lacking neutralizing activity is unclear and requires further evaluation.

Ultrasonography for pregnancy diagnosis and evaluation in queens.

In the present paper, we describe the clinical utility of ultrasonography for diagnosing and evaluating pregnancy in domestic cats. Ultrasonography is a non-invasive technique that permits an accurate diagnosis of pregnancy and allows serial evaluation of the developing embryo/fetus and the extrafetal structures. The first ultrasonographic indication of pregnancy is a gestational chamber seen on day 10 after mating as a small circular anechoic structure. From day 30, it is possible to recognize different fetal organs, and between 38 and 43 days, the gender of the fetus can be determined. Measurements obtained during the second half of gestation can be used to determine fetal age and calculations can then be made that may more accurately predict the time of parturition. Further studies are needed in the queen to determine the applicability of the echo-Doppler technique used routinely in human obstetric medicine. This type of ultrasonography could potentially provide useful information about fetal health and the maturity of the placenta.

In-stent neointimal proliferation correlates with the amount of residual plaque burden outside the stent: an intravascular ultrasound study.

BACKGROUND: The aim of this study was to evaluate the relationship between residual plaque burden after coronary stent implantation and the development of late in-stent neointimal proliferation. METHODS AND RESULTS: Between January 1996 and May 1997, 50 patients underwent intravascular ultrasound (IVUS) interrogation at 6+/-1.2 months after coronary stent implantation in native coronary arteries. IVUS images were acquired with a motorized pullback, and cross-sectional measurements were performed within the stents at 1-mm intervals. The following measurements were obtained: (1) lumen area (LA), (2) stent area (SA), (3) area delimited by the external elastic membrane (EEMA), (4) percent neointimal area calculated as (SA-LA/SA)x100, and (5) percent residual plaque area calculated as (EEMA-SA)/EEMAx100. Volume measurements within the stented segments were calculated by applying Simpson's rule. In the pooled data analysis of 876 cross sections, linear regression showed a significant positive correlation between percent residual plaque area and percent neointimal area (r=0.50, y= 45.03+0.29x, P<0.01). There was significant incremental increase in mean percent neointimal area for stepwise increase in percent residual plaque area. Mean percent neointimal area was 16.3+/-10.3% for lesions with a percent residual plaque area of <50% and 27.7+/-11% for lesions with a percent residual plaque area of >/=50% (P<0.001). The volumetric analysis showed that the percent residual plaque volume was significantly greater in restenotic lesions compared with nonrestenotic lesions (58.7+/-4.3% versus 51.4+/-5.7%, respectively; P<0.01). CONCLUSIONS: Late in-stent neointimal proliferation has a direct correlation with the amount of residual plaque burden after coronary stent implantation, supporting the hypothesis that plaque removal before stent implantation may reduce restenosis.

Energetic, structural, and antimicrobial analyses of beta-lactam side chain recognition by beta-lactamases.

BACKGROUND: Penicillins and cephalosporins are among the most widely used and successful antibiotics. The emergence of resistance to these beta-lactams, most often through bacterial expression of beta-lactamases, threatens public health. To understand how beta-lactamases recognize their substrates, it would be helpful to know their binding energies. Unfortunately, these have been difficult to measure because beta-lactams form covalent adducts with beta-lactamases. This has complicated functional analyses and inhibitor design. RESULTS: To investigate the contribution to interaction energy of the key amide (R1) side chain of beta-lactam antibiotics, eight acylglycineboronic acids that bear the side chains of characteristic penicillins and cephalosporins, as well as four other analogs, were synthesized. These transition-state analogs form reversible adducts with serine beta-lactamases. Therefore, binding energies can be calculated directly from K(i) values. The K(i) values measured span four orders of magnitude against the Group I beta-lactamase AmpC and three orders of magnitude against the Group II beta-lactamase TEM-1. The acylglycineboronic acids have K(i) values as low as 20 nM against AmpC and as low as 390 nM against TEM-1. The inhibitors showed little activity against serine proteases, such as chymotrypsin. R1 side chains characteristic of beta-lactam inhibitors did not have better affinity for AmpC than did side chains characteristic of beta-lactam substrates. Two of the inhibitors reversed the resistance of pathogenic bacteria to beta-lactams in cell culture. Structures of two inhibitors in their complexes with AmpC were determined by X-ray crystallography to 1.90 A and 1.75 A resolution; these structures suggest interactions that are important to the affinity of the inhibitors. CONCLUSIONS: Acylglycineboronic acids allow us to begin to dissect interaction energies between beta-lactam side chains and beta-lactamases. Surprisingly, there is little correlation between the affinity contributed by R1 side chains and their occurrence in beta-lactam inhibitors or beta-lactam substrates of serine beta-lactamases. Nevertheless, presented in acylglycineboronic acids, these side chains can lead to inhibitors with high affinities and specificities. The structures of their complexes with AmpC give a molecular context to their affinities and may guide the design of anti-resistance compounds in this series.

Usefulness of three-dimensional reconstruction for interpretation and quantitative analysis of intracoronary ultrasound during stent deployment.

We examined 49 coronary stents in 33 patients after angiographically guided optimization of the deployment by intracoronary ultrasound, and compared the findings of a conventional 2-dimensional analysis approach with the results obtained from an automatic lumen recognition provided by a 3-dimensional reconstruction system. The automatic lumen analysis demonstrated that only 15 stents (31%) fulfilled defined ultrasound criteria of adequate stent deployment, and that 5 of these cases were missed by the conventional approach, which systematically overestimated the dimensions of the minimal stent lumen.

Usefulness of on-line three-dimensional reconstruction of intracoronary ultrasound for guidance of stent deployment.

The additional information provided by automated on-line 3-dimensional (3-D) reconstruction of intracoronary ultrasound (ICUS) was assessed in 42 patients (62 stents) who underwent stent deployment after achieving an optimal quantitative angiographic result. In 10 of 42 patients, 3-D ICUS was also performed before stenting. ICUS images of stents and adjacent reference segments were acquired by using a motorized pullback at a constant speed (1 mm/s) and immediately processed in the catheterization laboratory. Optimal stent expansion was detected by 3-D ICUS in case of complete apposition of stent struts to the vessel wall. Furthermore, an attempt was made to maximize the intrastent lumen area to match lumen area of the reference segment and to cover with stents all the segments with residual significant lesions (plaque burden >50%). Three-dimensional automated reconstruction of ICUS was successful in 8 of 10 patients (80%) before, and in 36 of 42 patients (86%) after stent deployment. In all 8 patients who underwent successful 3-D ICUS assessment before stent implantation, the selection of stent length was facilitated by accurately measuring the lesion length. After stenting, 3-D ICUS modified the management strategy in 21 of 36 patients (58%), triggering additional high-pressure dilatations in 13 patients (36%) and additional stent deployment in 8 (22%). In conclusion, on-line 3-D ICUS facilitates stent selection and strongly modifies the revascularization strategy by accurately detecting stent underexpansion and presence of uncovered lesions.

Transient myocardial ischemia detected by Holter monitoring during the early post-infarction period.

BACKGROUND: On the basis of extensive studies concerning the prognostic value of Holter monitoring in patients with angina, we evaluated the clinical outcome of patients with transient ischemic episodes soon after myocardial infarction. METHODS: The incidence and clinical significance of myocardial ischemia, detected in the acute phase of myocardial infarction, were evaluated in 87 patients. Twenty-four-hour Holter recordings were obtained on the 2nd, 4th, 6th, and 12th hospital day. RESULTS: Myocardial ischemia was detected during at least one of the four recording periods in 28 patients (32%). A total of 157 ischemic episodes were documented. The proportion of recordings that showed transient myocardial ischemia progressively declined from 20% on the 2nd day to 5% on the 12th post-infarction day. Of the 157 ischemic episodes, 132 (84%) were silent and 25 (16%) were symptomatic. Transient ST-segment elevation was present in 99 of the 157 episodes (63%), while transient ST-segment depression occurred in the remaining 58 of the 157 cases (37%). One or more in-hospital cardiac events (reinfarction, acute pulmonary edema, ventricular tachycardia or fibrillation, cardiac death) were more frequent in patients with (group I) than in those without (group II) transient myocardial ischemia [nine out of 28 (32%) versus six out of 59 (10%); P < 0.03]. At follow-up (mean 11.5 +/- 2 months) the incidence of cardiac events (angina, reinfarction, heart failure, ventricular tachycardia or fibrillation, revascularization procedures, cardiac death, sudden death) was comparable in the two groups [four out of 24 (17%) versus 10 out of 49 (20%); NS]. Predischarge exercise testing, performed in 64 patients (74%), showed myocardial ischemia in 50%; the percentage did not vary significantly between group I and group II patients. Moreover, a positive exercise test was not predictive of major cardiac events at follow-up. CONCLUSION: Transient myocardial ischemia, frequently silent, is not uncommon in the acute phase of myocardial infarction and progressively decreases during the in-hospital stay. Its recognition in the subacute phase of myocardial infarction may lead to the identification of a subset of patients at the highest risk of early major complications, who may benefit from aggressive diagnostic and therapeutic strategies.