Frequency-noise measurements of optical frequency combs by multiple fringe-side discriminator

open5noThe frequency noise of an optical frequency comb is routinely measured through the hetherodyne beat of one comb tooth against a stable continuous-wave laser. After frequency-to-voltage conversion, the beatnote is sent to a spectrum analyzer to retrive the power spectral density of the frequency noise. Because narrow-linewidth continuous-wave lasers are available only at certain wavelengths, heterodyning the comb tooth can be challenging. We present a new technique for direct characterization of the frequency noise of an optical frequency comb, requiring no supplementary reference lasers and easily applicable in all spectral regions from the terahertz to the ultraviolet. The technique is based on the combination of a low finesse Fabry-Perot resonator and the so-called "fringe-side locking" method, usually adopted to characterize the spectral purity of single-frequency lasers, here generalized to optical frequency combs. The effectiveness of this technique is demonstrated with an Er-fiber comb source across the wavelength range from 1 to 2 μm.Coluccelli, Nicola; Cassinerio, Marco; Gambetta, Alessio; Laporta, Paolo; Galzerano, GianlucaColuccelli, Nicola; Cassinerio, Marco; Gambetta, Alessio; Laporta, Paolo; Galzerano, Gianluc

The optical frequency comb fibre spectrometer

Optical frequency comb sources provide thousands of precise and accurate optical lines in a single device enabling the broadband and high-speed detection required in many applications. A main challenge is to parallelize the detection over the widest possible band while bringing the resolution to the single comb-line level. Here we propose a solution based on the combination of a frequency comb source and a fibre spectrometer, exploiting all-fibre technology. Our system allows for simultaneous measurement of 500 isolated comb lines over a span of 0.12 THz in a single acquisition; arbitrarily larger span are demonstrated (3,500 comb lines over 0.85 THz) by doing sequential acquisitions. The potential for precision measurements is proved by spectroscopy of acetylene at 1.53 μm. Being based on all-fibre technology, our system is inherently low-cost, lightweight and may lead to the development of a new class of broadband high-resolution spectrometers

Finding and treating gaucher disease type 1 - The role of the haematologist

Gaucher disease (GD) type 1 is the most common lysosomal storage disease and the most common genetic disorder among Ashkenazi Jews. The majority of patients with GD present with unexplained splenomegaly and/or thrombocytopenia, and the disorder often affects children; consequently, haematologists and paediatricians are ideally placed to diagnose this condition. Prompt management of GD type 1 using enzyme-replacement therapy or substrate reduction therapy can reduce the risk of developing long-term GD complications and reverse many of the initial signs/symptoms, thereby improving both quality and duration of life. Treatment is most effective when initiated early; consequently, a prompt diagnosis is essential. Despite this, the average time to diagnosis following the onset of clinical symptoms is 4 years. Reasons for the delay include the heterogeneous nature of the disease, together with a lack of awareness of rare haematological disorders and the benefits of early treatment. Indeed, studies show that only 20% of haematologists consider GD type 1 in their differential diagnosis for patients presenting with splenomegaly and/or thrombocytopenia. To help raise awareness of GD, reduce the diagnostic delay and prevent unnecessary tissue biopsies, simple diagnostic algorithms and screening tools have been developed and validated, both in adults and in children

Isolated office hypertension : A 3-year follow-up study

The study aimed to evaluate, over a 3-year period, the progression towards sustained hypertension and left ventricular (LV) changes in patients with isolated office (IO) hypertension (office BP140 and/or 90 mmHg, daytime BP130/80 mmHg). After 3 years from the basal evaluation, 38 subjects with basal normal BP and 42 subjects with basal IO hypertension underwent a second 24-h BP monitoring and echocardiography; 19 patients of the basal IO hypertension group were not revaluated because they had already developed ambulatory hypertension and were on antihypertensive treatment. At the second evaluation, the 38 normotensive subjects had unchanged BP and LV parameters; 25 IO hypertensives have developed sustained hypertension. Considering them together with the 19 patients already treated, 72% of 61 IO hypertensives developed ambulatory hypertension over a 3-year period. The patients who subsequently developed hypertension differed from the group who did not only for lower basal values of LV diastolic parameters; all the patients with basal LV hypertrophy and/or preclinical diastolic impairment subsequently developed sustained hypertension. In conclusion, IO hypertensive patients show a high rate of progression towards sustained hypertension. Basal LV hypertrophy and/or preclinical diastolic dysfunction were the only markers of a greater risk of becoming hypertensives

An Intriguing Case of Anaemia and Splenomegaly

Objectives: Thrombocytopenia and splenomegaly are common features in several haematological disorders. Gaucher disease (GD) is a rare lysosomal storage disorder frequently characterized by thrombocytopenia and splenomegaly, which represents a clinical challenge for haematologists and internists. Case: We describe the case of a 37-year-old patient with a diagnosis of spherocytosis since childhood, who developed hepatic failure and presented striking features of GD including hepatosplenomegaly, bone fractures and post-partum bleeding. We reconsidered the diagnosis of spherocytosis and investigated Gaucher disease. Conclusion: GD should be considered in the differential diagnosis of thrombocytopenia and splenomegaly

Liver steatosis is highly prevalent and is associated with metabolic risk factors and liver fibrosis in adult patients with type 1 Gaucher disease

Background and Aims: Gaucher disease (GD) is associated with peculiar metabolic abnormalities (ie hypermetabolic state, peripheral insulin resistance, dyslipidaemia), partially reverted by enzyme replacement therapy (ERT) at the expense of weight gain. Such metabolic alterations together with an unhealthy lifestyle acquired by an ageing GD population may favour the development of liver steatosis. We aimed at evaluating the prevalence of significant liver steatosis and at identifying the factors associated with liver steatosis in a cohort of patients with type 1 GD. Methods: Twenty adult type 1 GD patients from an Italian academic referral centre were prospectively submitted to vibration-controlled transient elastography (Fibroscan®) with controlled attenuation parameter (CAP); significant steatosis was defined as CAP values ≥250 dB/min. Results: Median CAP values were 234 [165-358] dB/min and 8 patients (40%) had significant steatosis. Significant steatosis was associated with indices of adiposity (weight, BMI and waist circumference), high blood pressure, insulin resistance and metabolic syndrome. GD-related variables and dose and duration of ERT were not associated with significant steatosis. In the subgroup of 16 patients on stable ERT for at least 24 months, CAP resulted significantly and positively associated with liver stiffness (rho 0.559, P =.024). Conclusions: Significant steatosis is highly prevalent in adult type 1 GD patients and is strongly associated with a worse metabolic profile, featuring metabolic dysfunction-associated fatty liver disease (MAFLD). MAFLD may determine liver fibrosis progression in GD patients on stable ERT and may be a risk factor for long-term liver-related complications

Linfopenia B: Reporte de Casos

1 p.La linfopenia B (<2%) es un hallazgo poco frecuente. Cuando se acompaña de niveles séricos de inmunoglobulinas (Igs) menores a 2DS para la edad permite realizar un diagnóstico (Dx) posible de Agammaglobulinemia (AG). Es una Inmunodeficiencia Primaria predominantemente de anticuerpos de herencia ligada al X (AG-X) en la mayoría de los casos.Fil: Raimondo, Natalia. Hospital de Niños Santísima Trinidad; ArgentinaFil: Selina, Manrique. Hospital de Niños Santísima Trinidad; ArgentinaFil: Cassinerio, Adriana. Hospital de Niños Santísima Trinidad; ArgentinaFil: Mosca, Liliana. Hospital de Niños Santísima Trinidad; ArgentinaFil: Orellano, Julio. Hospital de Niños Santísima Trinidad; ArgentinaPediatrí