Peregrine solitons and resonant radiation in cubic and quadratic media.

We present the fascinating phenomena of resonant radiation emitted by transient rogue waves in cubic and quadratic nonlinear media, particularly those shed from Peregrine solitons, one of the main wavepackets used today to model real-world rogue waves. In cubic media, it turns out that the emission of radiation from a Peregrine soliton can be attributed to the presence of higher-order dispersion, but is affected by the intrinsic local longitudinal variation of the soliton wavenumber. In quadratic media, we reveal that a two-color Peregrine rogue wave can resonantly radiate dispersive waves even in the absence of higher-order dispersion, subjected to a phase-matching mechanism that involves the second-harmonic wave, and to a concomitant difference-frequency generation process. In both cubic and quadratic media, we provide simple analytic criteria for calculating the radiated frequencies in terms of material parameters, showing excellent agreement with numerical simulations.

Transplantation to save the life, TSH screening to save the brain: A report and brief literature review of autoimmune thyroid disease after HSCT for severe combined immunodeficiency.

Autoimmune thyroid disease has been described as a complication of HSCT for different indications and as a manifestation of inborn errors of immunity, like SCID. A 1-month female was diagnosed with RAG1-mutated SCID and received allogenic HSCT. She developed autoimmune hypothyroidism 5 months after transplantation and was treated with levo-thyroxine with a good response. Autoimmune thyroid disease can develop after HSCT during the immune reconstitution phase, leading to potentially severe neurological and growth impairment, particularly in SCID patients, often transplanted during the first year of life. Recommendations regarding early and frequent vigilance for thyroid function are needed in these patients.

Spatial Beam Self-Cleaning in Second-Harmonic Generation.

We experimentally demonstrate the spatial self-cleaning of a highly multimode optical beam, in the process of second-harmonic generation in a quadratic nonlinear potassium titanyl phosphate crystal. As the beam energy grows larger, the output beam from the crystal evolves from a highly speckled intensity pattern into a single, bell-shaped spot, sitting on a low energy background. We demonstrate that quadratic beam cleanup is accompanied by significant self-focusing of the fundamental beam, for both positive and negative signs of the linear phase mismatch close to the phase-matching condition.

X-linked hypophosphatemic rickets: an Italian experts' opinion survey.

BACKGROUND: X-linked hypophosphatemic rickets (XLH) is the first cause of inherited hypophosphatemia and is caused by mutation in the PHEX gene, resulting in excessive expression of the phosphaturic factor FGF23. Symptoms are mainly related to rickets in children and osteomalacia in adults and cause several complications that can be highly invalidating. Due to its rarity, XLH is poorly known and diagnosis is frequently delayed. Conventional treatment is based on oral phosphate salts supplementation and activated vitamin D analogs, which however, cannot cure the disease in most cases. OBJECTIVE: Due to the low prevalence of XLH, an experts' opinion survey was conducted across Italian centers to collect data on XLH and on its management. METHODS: A questionnaire was developed by a group of experts to collect data on XLH epidemiology, diagnosis and treatment in Italy. RESULTS: Data from 10 Italian centers (nine of which pediatric) on 175 patients, followed between 1998 and 2017, were included in the survey. Most patients were followed since childhood and 63 children became adults during the investigated period. The diagnosis was made before the age of 1 and between 1 and 5 years in 11 and 50% of cases, respectively. Clinically apparent bone deformities were present in 95% of patients. These were ranked moderate/severe in 75% of subjects and caused growth stunting in 67% of patients. Other frequent complications included bone pain (40%), dental abscesses (33%), and dental malpositions (53%). Treatment protocols varied substantially among centers. Nephrocalcinosis was observed in 34% of patients. Tertiary hyperparathyroidism developed in 6% of patients. CONCLUSIONS: XLH remains a severe condition with significant morbidities.

Statistics of vector Manakov rogue waves.

We present a statistical analysis based on the height and return-time probabilities of high-amplitude wave events in both focusing and defocusing Manakov systems. We find that analytical rational or semirational solutions, associated with extreme, rogue wave (RW) structures, are the leading high-amplitude events in this system. We define the thresholds for classifying an extreme wave event as a RW. Our results indicate that there is a strong relationship between the type of RW and the mechanism which is responsible for its creation. Initially, high-amplitude events originate from modulation instability. Upon subsequent evolution, the interaction among these events prevails as the mechanism for RW creation. We suggest a strategy for confirming the basic properties of different extreme events. This involves the definition of proper statistical measures at each stage of the RW dynamics. Our results point to the need for redefining criteria for identifying RW events.

Zero focusing via competing nonlinearities in beta-barium-borate crystals.

We investigate nonlinear focusing behavior of light beams propagating in beta-barium-borate crystals under mismatched second-harmonic generation. We clearly identify experimentally multiple self-focusing and defocusing regions against the orientation angle and the condition where competing quadratic and cubic nonlinearities perfectly compensate each other (zero-focusing point).

Competing wave-breaking mechanisms in quadratic media.

We show that second-harmonic generation in the regime of weak dispersion/diffraction can exhibit a coexistence of wave breaking mechanisms, such that a gradient catastrophe yielding a dispersive shock wave competes with modulational instability, leading to the generation of wavetrains with incommensurate frequencies and eventually to the destruction of the shock wave-train.

Severe hypoglycemic episodes: a persistent threat for children with Type 1 diabetes mellitus and their families.

BACKGROUND: As lowering glycated hemoglobin (HbA1c) levels is still the main goal of insulin treatment, severe hypoglycemia (SH) remains a common experience in children with Type 1 diabetes mellitus (T1DM) and their families. AIM: This study aims to evaluate the incidence and the clinical features of SH episodes in our Centre in the last 20 yr. SUBJECTS AND METHODS: We analyzed SH incidence in 269 patients (pts) diagnosed from 1990 to 2010 (total follow-up 2212.9 pts/yr). Inclusion criteria were at least 3 visits/yr and 1-yr follow- up. SH episode was defined as any condition of low blood glucose requiring third-party assistance. RESULTS: 50.2% of patients experienced at least 1 SH episode for a total of 345 episodes. Whole incidence was 15.6/100 pts/yr, slightly different between first and second decade (12.6 vs 16.5, p=0.047). HbA1c at the time of SH was lower in the non-basal bolus group (7.4±1.3 vs 8.2±1.4; p=0.0001) and worsened 3 months later (p=0.0001). Impaired awareness was the main or only symptom in 43.5%. SH occurred at night in 32% of patients; they were significantly younger than those with SH at other times. Five SH episodes or more occurred in 8.1% of patients who presented a lower HbA1c, a younger age and shorter disease duration than the other patients. HbA1c at first SH was negatively correlated with number of SH (r=-0.20; p=0.05). CONCLUSIONS: Despite the advent of new insulin regimens, we confirm that SH still represents a relevant risk and a current threat for patients with T1DM and their families.

Dispersive shock waves in phase-mismatched second-harmonic generation.

We investigate wave-breaking and dispersive shock wave formation driven by a pulse undergoing second-harmonic generation in a quadratic medium. We show that the process is accessible in the regime of high phase-mismatch (cascading limit) and weak dispersion. Insight into the phenomenon is obtained by means of a suitable hydrodynamic reduction of the equations that govern the mixing.

Autoimmune-polyendocrinopathy-candidiasis-ectodermal-dystrophy in Calabria: clinical, immunological and genetic patterns.

UNLABELLED: Autoimmune polyendocrinopathy-candidiasis-ectodermal- dystrophy (APECED), also known as autoimmune polyendocrine syndrome type 1 (APS-1), is a very rare disease. Diagnosis requires the presence of at least two of three major clinical features: chronic mucocutaneous candidiasis, chronic hypoparathyroidism, and Addison's disease. DESIGN: In this study, we analyzed Autoimmune Regulator (AIRE) gene mutations and genotype-phenotype correlation in APECED patients originating from Calabria, a region in the south of Italy. PATIENTS AND METHODS: Four patients and their first-degree relatives were evaluated for clinical manifestations, autoantibody presence and AIRE gene mutations. RESULTS: Three patients carried a homozygous W78R mutation on exon 2, typical of patients with APECED from Apulia; the fourth patient had a homozygous R203X mutation on exon 5, typical of APECED patients from Sicily. Clinical disease expression showed wide variability. Analysis of relatives allowed the identification of 6 heterozygotes, none of whom showed major findings of APECED. CONCLUSIONS: No AIRE gene mutations specific to Calabria were found in patients with APS-1, but mutations similar to those in patients from Apulia and Sicily. Heterozygosity for AIRE gene mutation is not associated with major findings of APECED.

The SHOX gene: a new indication for GH treatment.

Short stature homeobox-containing (SHOX) gene mutations causing haploinsufficiency have been reported in idiopathic short stature, but the real prevalence of this defect in the population with growth failure is debated. Based on current data, the prevalence of SHOXdefect (SHOX-D) has been calculated to have occurred in at least 1 in 2,000 children. This occurrence rate is higher than that of classic GH deficiency or Turner syndrome. In all probability, the real prevalence of SHOX-D will increase in the future with the improvement of the genetic analysis with investigations for point mutations in the enhancer sequences or for deletions in other parts of this region. A selection criterion to individuate the most appropriate candidates eligible for the SHOX region analysis has been suggested based on the evaluation of a disproportional short stature. The efficacy of GH treatment in these patients has recently been demonstrated with results that are similar to those observed in Turner syndrome.

Synthesis of picosecond pulses by spectral compression and shaping of femtosecond pulses in engineered quadratic nonlinear media.

Narrow-bandwidth picosecond pulses of predetermined spectral and temporal shapes are generated with high efficiency by frequency conversion of femtosecond pulses in lithium tantalate crystals with engineered quasi-phase-matching structures. We give examples of the synthesis of Gaussian and super-Gaussian picosecond pulses and also of a pair of synchronized phase-coherent picosecond pulses with a predetermined carrier-frequency difference.

Narrow-bandwidth picosecond pulses by spectral compression of femtosecond pulses in second-order nonlinear crystals.

We introduce a simple approach for the efficient generation of tunable narrow-bandwidth picosecond pulses synchronized to broadband femtosecond ones. Second harmonic generation in the presence of large group velocity mismatch between the interacting pulses transfers a large fraction of the energy of a broadband fundamental frequency pulse into a narrowband second harmonic one. Using a periodically poled stoichiometric lithium tantalate crystal coupled to an infrared optical parametric amplifier, we generated 200-nJ pulses with spectral width lower than 8.5 cm(-1) and tunability from 720 to 890 nm. Energy scaling and extension of the tuning range are straightforward.

Spectral shift of femtosecond pulses in nonlinear quadratic PPSLT Crystals.

Spectral blue- and red-shifts in a range of 100 nm are achieved by propagating 40 fs pulses with a 70 nm spectrum centered at 1450 nm in a 25-mm-long periodically poled stoichiometric lithium tantalate crystal. We show experimentally that these shifts, originating from a phase-mismatched second harmonic generation process under conditions of strong group velocity mismatch, can be efficiently controlled by acting on pulse intensity and phase-mismatch.