Highly efficient generation of narrowband terahertz radiation driven by a two-spectral-line laser in PPLN.

We demonstrate record ∼0.9% efficiencies for optical conversion to narrowband (<1% relative bandwidth) terahertz (THz) radiation by strongly cascaded difference frequency generation. These results are achieved using a novel, to the best of our knowledge, laser source, customized for high efficiencies, with two narrow spectral lines of variable separation and pulse duration (≥250 ps). THz radiation generation in 5% MgO-doped periodically poled lithium niobate (PPLN) crystals of varying poling period was explored at cryogenic and room temperature operation as well as with different crystal lengths. This work addresses an increasing demand for high-field THz radiation pulses which has, up to now, been largely limited by low optical-to-THz radiation conversion efficiencies.

Frequency-comb-based laser system producing stable optical beat pulses with picosecond durations suitable for high-precision multi-cycle terahertz-wave generation and rapid detection.

We generate temporally modulated optical pulses with a beat frequency of 255 GHz, a duration of 360 ps, and a repetition rate of 2 MHz. The temporal envelope, beat frequency, and repetition rate are computer-programmable. A frequency comb serves as a phase and frequency reference for the locking of two laser lines. The system enables beat frequencies that are adjustable in steps of the frequency comb's repetition rate and exhibit Hz-level precision and accuracy. We expect the optical beat pulses to be well suited for versatile multi-cycle terahertz-wave generation with controllable carrier-envelope phase. We demonstrate that the inherent synchronization of the frequency comb's ultra-short pulse train and the synthesized optical beat (or later the multi-cycle terahertz) pulses enables rapid and phase-sensitive sampling of such pulses.

The Detection of Genetic Parameters for Prognostic Stratification of Neuroblastoma Using Multiplex Ligation-Dependent Probe Amplification Technique.

BACKGROUND: Neuroblastoma (NB) is a neoplasm of the sympathetic nervous system and the most frequent extra cranial solid tumor of early childhood. These tumors display a wide range of clinical behavior and are characterized by complex chromosomal changes, some of which are associated with distinct clinical phenotypes. We investigated the contribution of genetic variables to staging and histology by logistic regression analyses. METHODS: We used multiplex ligation-dependent probe amplification (MLPA) to detect segmental genomic imbalances and gene copy number changes in 202 primary NBs. RESULTS: Cases with NB were categorized into four distinct groups based on the genomic changes. Group 1 (48 cases, 23.7%) contained tumors with a 1p deletion and/or MYCN gene amplification (MNA). Group 2 included 46 cases (22.8%) with 3p and/or 11q deletions without 1p deletion and MYCN gene amplification. Tumors harboring at least two commonly observed deletions with or without MNA were classified as Group 3 (25 cases, 12.4%). Tumors with chromosomal imbalance other than MYCN gene amplification and 1p, 3p, and 11q deletions were in Group 4 (83 cases, 41.1%). MYCN gene amplification and 17q gain were significant predisposing factors for unfavorable histology. Significant correlations were detected between 1p deletion and MYCN gene amplification; 3p and 11q deletions; and 11q deletion and 17q gain. CONCLUSION: MLPA can be used effectively to simultaneously detect multiple genomic imbalances and these changes can be utilized to classify neuroblastomas by prognostic subtypes. The genetic changes detected in NB in this study and their associations with clinical characteristics are in line with previously published reports.

Paroxysmal Complete Atrioventricular Block: A Rare Cause of Syncope in Children.

Paroxysmal atrioventricular block (PAVB) is a rare cause of syncope, mostly reported in adults. In the present study, a child with recurrent syncope due to PAVB is reported. A 12-year old boy was admitted due to syncope. Some syncopal episodes were consistent with vasovagal syncope, while others had atypical features. Electrocardiography, echocardiography and 24-hour electrocardiography monitoring were normal. Head-up tilt table test revealed mixed type vasovagal syncope. With beta-blocker treatment, the frequency of syncopal episodes decreased; however, the episodes with atypical features continued. Intracardiac electrophysiological study was normal, but repeated external loop recorder monitoring revealed transient AVB during a syncopal episode. In children with syncope with atypical features, PAVB should be kept in mind. Repeated external loop recorder monitoring may be useful in the diagnosis of such seldom seen arrhythmic causes.

Partial anomalous pulmonary venous return associated with vascular anomalies of the aorta: multidetector computed tomography findings.

Partial anomalous pulmonary venous return (PAPVR) is a congenital anomaly that involves drainage of one to three pulmonary veins directly into the right heart or systemic venous system, creating a partial left-to-right shunt. This drainage is associated with cardiac abnormalities such as mitral stenosis and pulmonary stenosis, patent ductus arteriosus, and atrial septal defects. We report a case of PAPVR associated with vascular anomalies of the aorta by multidetector computed tomography in an adult female patient.

A case of Bonneau syndrome associated with multiple renal cortical cysts.

We describe a 2-month-old girl with congenital anomalies including facial anomalies, complex cardiac anomalies, polysyndactyly, dysgenesis of distal extremities and bilateral multiple renal cysts. The proband was the child of first-cousin parents. Clinical synopsis in Bonneau syndrome (OMIM: 263630) is polysyndactyly and cardiac malformation. In addition, liver anomalies were reported in two patients. We discuss polysyndactyly and cardiac malformation with bilateral multiple renal cysts, a combination not reported previously.

Postoperative hepatic laceration in a child with type 3 von Willebrand disease.

We report an unusual postoperative complication (hepatic laceration) in a child with type 3 vWD, who has not received any prophylaxis.