Ultrafast optical ranging using microresonator soliton frequency combs.

Light detection and ranging is widely used in science and industry. Over the past decade, optical frequency combs were shown to offer advantages in optical ranging, enabling fast distance acquisition with high accuracy. Driven by emerging high-volume applications such as industrial sensing, drone navigation, or autonomous driving, there is now a growing demand for compact ranging systems. Here, we show that soliton Kerr comb generation in integrated silicon nitride microresonators provides a route to high-performance chip-scale ranging systems. We demonstrate dual-comb distance measurements with Allan deviations down to 12 nanometers at averaging times of 13 microseconds along with ultrafast ranging at acquisition rates of 100 megahertz, allowing for in-flight sampling of gun projectiles moving at 150 meters per second. Combining integrated soliton-comb ranging systems with chip-scale nanophotonic phased arrays could enable compact ultrafast ranging systems for emerging mass applications.

Coherent modulation up to 100 GBd 16QAM using silicon-organic hybrid (SOH) devices.

We demonstrate the generation of higher-order modulation formats using silicon-based inphase/quadrature (IQ) modulators at symbol rates of up to 100 GBd. Our devices exploit the advantages of silicon-organic hybrid (SOH) integration, which combines silicon-on-insulator waveguides with highly efficient organic electro-optic (EO) cladding materials to enable small drive voltages and sub-millimeter device lengths. In our experiments, we use an SOH IQ modulator with a π-voltage of 1.6 V to generate 100 GBd 16QAM signals. This is the first time that the 100 GBd mark is reached with an IQ modulator realized on a semiconductor substrate, leading to a single-polarization line rate of 400 Gbit/s. The peak-to-peak drive voltages amount to 1.5 Vpp, corresponding to an electrical energy dissipation in the modulator of only 25 fJ/bit.

Mode-multiplexed transmission over conventional graded-index multimode fibers.

We present experimental results for combined mode-multiplexed and wavelength multiplexed transmission over conventional graded-index multimode fibers. We use mode-selective photonic lanterns as mode couplers to precisely excite a subset of the modes of the multimode fiber and additionally to compensate for the differential group delay between the excited modes. Spatial mode filters are added to suppress undesired higher order modes. We transmit 30-Gbaud QPSK signals over 60 WDM channels, 3 spatial modes, and 2 polarizations, reaching a distance of 310 km based on a 44.3 km long span. We also report about transmission experiments over 6 spatial modes for a 17-km single-span experiment. The results indicate that multimode fibers support scalable mode-division multiplexing approaches, where modes can be added over time if desired. Also the results indicate that mode-multiplexed transmission distance over 300 km are possible in conventional multimode fibers.

Wavelength-selective switch with direct few mode fiber integration.

The first realization of a wavelength-selective switch (WSS) with direct integration of few mode fibers (FMF) is fully described. The free-space optics FMF-WSS dynamically steers spectral information-bearing beams containing three spatial modes from an input port to one of nine output ports using a phase spatial light modulator. Sources of mode dependent losses (MDL) are identified, analytically analyzed and experimentally confirmed on account of different modal sensitivities to fiber coupling in imperfect imaging and at spectral channel edges due to mode clipping. These performance impacting effects can be reduced by adhering to provided design guidelines, which scale in support of higher spatial mode counts. The effect on data transmission of cascaded passband filtering and MDL build-up is experimentally investigated in detail.

Digital coherent superposition for performance improvement of spatially multiplexed coherent optical OFDM superchannels.

We demonstrate the use of digital coherent superposition to improve the performance of space-division-multiplexed (SDM) 676-Gb/s OFDM-16QAM superchannels, achieving ~4 dB improvement in OSNR by using two SDM copies and 1075-km (14 x 76.8 km) transmission over a seven-core-fiber with an effective aggregate spectral efficiency of 23.7 b/s/Hz. We further show that the performance improvement from the coherent superposition is retained in the nonlinear transmission regime through coordinated scrambling of signal constellations at the transmitter and appropriate unscrambling at the receiver, by using a series of simple scrambling functions.

Video-assisted thoracoscopic surgery as a primary intervention in pediatric parapneumonic effusion and empyema.

The use and effectiveness of video-assisted thoracoscopic surgery (VATS) for the treatment of empyema and complex parapneumonic collections in pediatric patients is well documented. Timing of this intervention still remains controversial. We reviewed our experience with VATS to determine if it should be used as the initial procedure in children with pleural collections. We reviewed all pediatric (age younger than 17 years) patients with a diagnosis of pneumonia admitted between July 1998 and June 2008. Demographics, comorbidities, laboratory data, and hospital length of stay (LOS) were evaluated. Patients were divided into groups: those who only had thoracentesis or thoracostomy (Group A), those who underwent a procedure and then required VATS (Group B), and those who went directly to VATS (Group C). We identified 382 patients admitted with pneumonia. Of these, 79 (21%) required a thoracic drainage procedure. Overall, 49 (67%) of patients with a thoracic fluid collection underwent VATS at some point. With regard to type of intervention, there was no statistical difference noted in clinical variables. Thirty (38%) patients were in Group A, 18 (22%) in Group B, and 31 (39%) in Group C. LOS for Group C (10.5 days) was significantly (P < 0.05) shorter than for both Group A (14.8 days) and Group B (15 days). Only two (6%) patients required conversion to open thoracotomy. A high percentage of children initially treated by tube thoracostomy eventually require additional interventions, leading to increased LOS. As a result of its simplicity, safety, and efficacy, VATS pleural evacuation can be recommended as the initial intervention in pediatric parapneumonic effusions and empyema in patients who do not require emergent drainage.

Record high-speed short-range transmission over 1 mm core diameter POF employing DMT modulation.

We report multigigabit/second transmission capacity in 1 mm core diameter graded index plastic optical fiber (POF) exploiting off-the-shelf low-cost components and discrete multitone (DMT) modulation. Transmission capacities of 10.1 Gbits/s x 15 m and 12.7 Gbits/s x 3 m are achieved for average bit-error rates less than 10(-3).

Primary thoracoscopic gross total resection of neuroblastoma.

BACKGROUND: Thoracic neuroblastomas are generally less aggressive and have a better prognosis than those arising below the diaphragm. Our purpose was to study the safety and efficacy of thoracoscopic resection and to evaluate tumor data and patient outcomes. PATIENTS AND METHODS: We reviewed the records of patients who underwent primary thoracoscopic resection of neuroblastoma (NB) between 1998 and 2002. Data included demographics, symptoms, size, location, operative time, complications, hospital stay, histology, biologic markers, adjuvant therapy, and outcome. RESULTS: Five patients (age range, 9 to 44 months) underwent thoracoscopic resection of NB. Three of the patients had neurological symptoms. Tumor size ranged from 2.1 to 6.0 cm. Two tumors were apical, three supradiaphragmatic. Primary thoracoscopic gross total resection was achieved in all 5 cases, all of which were stage 1. Operative time ranged from 64 to 175 minutes. The only complications were two cases of small tumor spillage. Hospital stay was 1 to 4 days. Histology ranged from ganglioneuroma to differentiating NB, with a favorable classification in 4 of 5 cases. None of the tumors were N-Myc amplified. Chemotherapy or radiation therapy was not indicated for any patient. All are alive with no evidence of disease at 14 to 55 months' follow-up. CONCLUSION: Primary gross total resection of mediastinal NB can be achieved safely and effectively by a thoracoscopic approach. In our series, most tumors had favorable histology and biology, and all appear to be potentially treatable by primary thoracoscopic resection alone.

Diagnostic laparoscopy with planned appendectomy: an integral step in the evaluation of unexplained right lower quadrant pain.

Recurrent right lower quadrant (RLQ) abdominal pain is often difficult to diagnose and treat. We reviewed our experience with diagnostic laparoscopy with planned appendectomy for children with unexplained RLQ pain. This procedure was performed when the cause of atypical RLQ pain could not be diagnosed by comprehensive medical and radiological evaluation. Outcome data was obtained at office visits and by telephone. From 1997 to 2000, 30 children (22 female) presented with unexplained RLQ pain. Ages ranged from 5 to 16 years (mean 11 years). Symptoms had been present from 6 days to 2 years (median 6 weeks). Gross and/or histological appendiceal abnormalities were found in 26 children (87%). Incidental findings included patent processus vaginalis in one and adnexal cysts in six. Two complications occurred: pelvic fluid collection and umbilical suture reaction. At initial follow-up, 29 patients (97%) were pain-free. Long-term follow-up was continued through 2002. At a median of 19 months (range 2-47 months), 25 of 28 patients (89%) reported no recurrence of their original pain. Our results confirm that the appendix is an important source of unexplained recurrent RLQ pain in children. Diagnostic laparoscopy with planned appendectomy is highly effective and should be considered an integral step in the management of these patients.

Amniotic sheets.

Seventeen cases of an aberrant sheet of tissue in the amniotic cavity are described to expand and clarify previous observations of this entity. The sheet of tissue demonstrates a thickened base and a free edge that undulates. The fetus moves freely about the sheet of tissue. There are no associated fetal deformities, and infants have no manifestations of the amniotic-band syndrome. Evidence suggests that these sheets may originate from "wrapping" of the amniochorionic membrane over a uterine synechia. These benign sheets of tissue should not be confused with the amniotic-band syndrome.

Parathyroid variants: US evaluation.

High-resolution (10-MHz) ultrasonography was performed in 181 patients with primary or secondary hyperparathyroidism during a 4-year period and evaluated retrospectively. Thirty-seven unusual-appearing parathyroid tumors were found among 235 parathyroid glands identified as abnormal. There was pathologic correlation in 36. The typical appearance of parathyroid adenoma was that of an oval hypoechoic or anechoic lesion in the neck, aligned in a craniocaudal direction and often posterior to the thyroid. Morphologic variations from the norm included giant size (n = 11) (4.6%), cystic changes in a solid tumor (n = 9) (3.8%), calcified glands (n = 6[in three patients]) (2.5%), a multilobulated configuration (n = 5) (2.1%), an inhomogeneous pattern (n = 5) (2.1%), and a parathyroid cyst (n = 1) (0.4%). Recognizing the abnormal parathyroid variants can increase the diagnostic accuracy of sonographic examination.

Experience with percutaneous indwelling peripheral arterial catheterization in neonates.

We present an experience with indwelling peripheral arterial catheters in preterm and term neonates. During a 12-month interval, 158 peripheral arterial lines were inserted in 115 infants. Eighty-eight infants required a single line while 27 infants required more than one line. Ninety-one catheters (57.6%) were electively removed, and 67 (42.4%) had to be discontinued prematurely. Vessels used included 110 radial arteries (69.6%), 27 posterior tibial arteries (17.1%), and 21 temporal arteries (13.3%). There were only two major complications (1.27%), both related to infections. The technique is described in detail. In our experience, with appropriate precaution, peripheral arterial cannulation has been a safe and reliable alternative to umbilical arterial catheterization.

Computed tomography of axial myopia.

Computed tomography (CT) is the primary imaging modality for evaluation of an orbital mass presenting as proptosis. Axial myopia is a benign cause of unilateral proptosis frequently encountered by the ophthalmologist. Identification of this condition by CT avoids additional investigation of the cause of the proptosis.

Follow-up of Wilms tumor: comparison of CT with other imaging procedures.

In a retrospective review, computed tomography (CT) was compared to a "routine" combination of other diagnostic imaging procedures used for follow-up evaluations of 13 children being treated for Wilms tumor. The examined variables were diagnostic accuracy, expense, and duration of examination. Results from 13 patients indicated that CT most accurately answers diagnostic queries pertinent to follow-up evaluation of Wilms tumor: the presence and extent of bilateral renal tumors, local recurrence, contralateral renal hypertrophy, and metastasis to liver or lungs, For diagnosing pulmonary metastases, CT was superior to conventional chest radiography both in sensitivity (4/4 vs. 2/4) and specificity (9/9 vs. 6/9). In depiction of liver metastases, CT (3/3) was superior to liver scintigraphy (2/3). The extent of bilateral Wilms tumors was better defined by CT than by urography. In no instances were the alternative diagnostic imaging studies found to be more accurate than CT for detection of recurrent tumor. Average cost for a CT examination ($344) is considerably less than the cost for a routine combination of the other imaging studies ($594). Examination time and diagnostic radiation does are also reduced using CT. Pending larger comparison studies, CT is recommended as the primary diagnostic method for follow-up evaluation of patients with Wilms tumor.