Algorithms for Weld Depth Measurement in Laser Welding of Copper with Scanning Optical Coherence Tomography.

In-process monitoring of weld penetration depth is possible with optical coherence tomography (OCT). The weld depth can be identified with OCT by statistical signal processing of the raw OCT signal and keyhole mapping. This approach is only applicable to stable welding processes and requires a time-consuming keyhole mapping to identify the optimal placement of a singular OCT measuring beam. In this work, we use an OCT measurement line for the identification of the weld depth. This approach shows the advantage that the calibration effort can be reduced as the measurement line requires only calibration in one dimension. As current literature focuses on weld depth measurement with a singular measurement point in the keyhole, no optimal algorithm exists for weld depth measurement with an OCT measurement line. We developed seven different weld depth processing pipelines and tested these algorithms under different weld conditions, such as stable deep penetration welding, unstable deep penetration welding, and heat conduction welding. We analyzed the accuracy of the weld depth processing algorithms by comparing the measured weld depth with metallographic weld depths. The intensity accumulation approach is identified as the most accurate algorithm for successful weld depth measurement with a scanning OCT measurement line.

In-Process Analysis of Melt Pool Fluctuations with Scanning Optical Coherence Tomography for Laser Welding of Copper for Quality Monitoring.

Optical coherence tomography (OCT) is an inline process monitoring technology for laser welding with various applications in the pre-, in-, and post-process. In-process monitoring with OCT focuses on the measurement of weld depth by the placement of a singular measurement beam into the keyhole. A laterally scanned measurement beam gives the opportunity to measure the keyhole and melt pool width. The processing region can be identified by separating higher signal intensities on the workpiece surface from lower signal intensities from the keyhole and the melt pool. In this work, we apply a scanned measurement beam for the identification of keyhole fluctuations. Different laser processing parameters are varied for laser welding of copper to evoke welds in the heat conduction regime, stable deep penetration welding, and unstable deep penetration welding. As keyhole instabilities can be related to the generation of spatter and other defects, we identified a feature for the classification of different weld statuses. In consequence, feedback can be given about possible defects which are originated in keyhole fluctuations (e.g., spatter).

Trimming laser-written waveguides through overwriting.

Femtosecond laser direct writing is widely used to create waveguide circuits for optical processing in applications including communications, astrophotonics, simulation and quantum information processing. The properties of these waveguide circuits can be sensitive to the fabrication conditions, meaning that noticeable variability can be present in nominally identical manufactured components. One potential solution to this problem is the use of device trimming, whereby additional laser fabrication is applied to optimise the optical properties of a device based upon measurement feedback. We show how this approach can be used in the manufacture of directional couplers by overwriting the laser-written structure to alter the coupling ratios.

Bilateral urinary calculi with discordant stone composition.

OBJECTIVES: To describe a cohort of bilateral stone formers with significantly different compositions between renal units. METHODS: Patients treated for bilateral nephrolithiasis over a 4-year period (2007-2010) were identified. Stones were categorized by dominant (≥50%) mineralogical component. Patients with significant compositional differences between renal units (discordant stone formers) were compared to patients with a similar stone type in each kidney. RESULTS: Fifteen of the 59 bilateral stone formers (25.4%) were discordant stone formers with significant differences in stone composition between renal units. Forty-four of the 59 patients (74.6%) had the same stone composition on each side. Thirty percent of discordant stones had calcium phosphate as the dominant stone component. Discordant stone formers were younger, had better renal function, and tended to have a larger stone burden (p < 0.05). CONCLUSIONS: A significant minority of bilateral stone formers form a different type of stone in each kidney. Local or micro-environmental etiologies may explain this phenomenon and may also account for failure of preventive therapy in some patients.

Determination of valid benchmarks for outcome indicators in cataract surgery: a multicenter, prospective cohort trial.

OBJECTIVE: To evaluate a systematic approach to derive valid benchmarks for 2 outcome indicators intended to ascertain quality in cataract surgery and to propose benchmark levels drawn from the study results. DESIGN: Prospective, multicenter cohort trial. PARTICIPANTS: A total of 1685 patients (206-239 eyes per trial site) were recruited consecutively at 7 study sites. The patients featured age-related cataracts and were undergoing unilateral cataract surgery in the period between January 2007 and August 2008. METHODS: Only patients with uncomplicated age-related cataracts were included. Cataract surgery was performed by phacoemulsification. The SN60AT (Alcon, Inc., Fort Worth, TX) intraocular lens (IOL) was used as a study lens. The IOL power was calculated using the SRK-T formula with a standardized A constant. Biometry was performed with the IOL Master (Carl Zeiss Meditex, Jena, Germany). Only highly experienced senior surgeons were involved. MAIN OUTCOME MEASURES: The outcome indicators 1 month and 3 months after surgery were the respective achievement of: (1) maximum absolute deviation of 0.5 diopter (D) between target refraction and postoperative spherical equivalent (primary end point, refractive accuracy); (2) best-corrected visual acuity of at least 0.8 (secondary end point, visual acuity outcome). RESULTS: In the pooled data, maximum absolute deviation of ± 0.5 D from target refraction was achieved in 80% (95% confidence interval, 78%-82%) of cases. Visual acuity of 0.8 or more was reached in 87% (95% confidence interval, 80%-93%) of cases. The results from the trial centers differed significantly in the outcomes of the primary and secondary end points (P<0.001). CONCLUSIONS: The study quantified benchmark levels for 2 outcome indicators in a standardized cataract surgery procedure. External confounding factors such as the comorbidity of patients, which cannot be influenced by the surgeon, were excluded. The derived benchmarks selectively illustrate the quality of the surgery and are superior to success rates published in the literature from unspecific data collections. This method is more suited for improving outcome quality by benchmarking. General methodologic problems are discussed, leading to recommendations for future study designs. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Paclitaxel inhibits ureteral smooth muscle cell proliferation and collagen production in the absence of cell toxicity.

PURPOSE: Urinary tract stricture results from excess collagen deposition at an injured area. Paclitaxel (Sigma-Aldrich®) prevents coronary artery restenosis by inhibiting vascular smooth muscle cell proliferation and collagen production. We evaluated the effects of paclitaxel on ureteral smooth muscle cell proliferation and collagen production. MATERIALS AND METHODS: Three phases of experiments were done in canine smooth muscle cells. In phase 1 we used proliferation assay to study smooth muscle cells exposed to various concentrations of paclitaxel during 7 days. Phase 2 consisted of 6-day enzyme-linked immunosorbent assay to detect the total amount of type III collagen produced by smooth muscle cells exposed to paclitaxel. In phase 3 we assessed smooth muscle cell membrane damage using a lactate dehydrogenase cytotoxicity assay in which cells were exposed to escalating paclitaxel concentrations for 14 days. RESULTS: Proliferation studies showed that 10 and 100 nM paclitaxel significantly inhibited ureteral smooth muscle cell proliferation. Enzyme-linked immunosorbent assay revealed significantly decreased type III collagen production at 100 nM. Cytotoxicity testing showed that 1 to 100 nM paclitaxel did not harm smooth muscle cells. CONCLUSIONS: Paclitaxel effectively inhibits canine ureteral smooth muscle cell proliferation and collagen production without toxicity to smooth muscle cells at concentrations up to 100 nM. These results may ultimately translate into new methods of preventing and treating urinary stricture disease.

Oral cavity metastasis of renal cell carcinoma: a case report.

INTRODUCTION: Despite being reported rarely, renal cell carcinoma is the third most frequent neoplasm to metastasize to the head and neck region preceded only by breast and lung cancer. Little information exists regarding the presentation and work-up of metastatic renal cell carcinoma in the oral cavity. CASE PRESENTATION: We report the case of a 63-year-old Caucasian man presenting with an oral cavity lesion that was painful and that had grown substantially over several months. Biopsy resulted in persistent bleeding requiring cautery and manual pressure. Immunoperoxidase testing was necessary to make the diagnosis of metastatic renal cell carcinoma and rule out other clear cell carcinomas of salivary gland origin. CONCLUSION: Metastatic renal cell carcinoma is part of the differential diagnosis for patients presenting with a new head or neck lesion in the setting of a history of kidney cancer. The physician needs to be prepared for the increased risk of bleeding and understand the importance of immunohistochemical staining to differentiate between metastatic renal cell carcinoma and malignancies of salivary origin. Unfortunately, the prognosis is invariably poor in these patients.

[Relationship and dependency in a hemodialysis unit]. / Relation et dépendance dans un service de dialyse.

Dialysis substitutes a deficient organ. To perform dialysis requires qualified nurses and physicians, necessitates time and is an expensive procedure. In a society which valorises autonomy, dialysis leads to dependency and therefore is associated with a very bad image. This loss of autonomy is one of the most common complains of dialyzed patients. For this reason, patients and caregivers valorise renal transplantation. It illustrates how the concept of autonomy and dependency may influence the life experience of dialyzed patients. We propose another approach which is oriented to the aspects of relations during dialysis. This approach is illustrated by two case reports. This concept allows to change the perception of the dialyzed patient and thus to change his life experience.

Laparoscopic living donor nephrectomy: a look at current trends and practice patterns at major transplant centers across the United States.

PURPOSE: Laparoscopic living donor nephrectomy is now the preferred technique for living donor renal transplantation. To our knowledge we provide the first published multi-institutional consensus describing practice patterns, technical considerations and interesting controversies involved in laparoscopic living donor nephrectomy. MATERIALS AND METHODS: We designed a survey with 33 multiple choice questions looking at demographics, patient selection, technical considerations, postoperative care and followup involved in laparoscopic living donor nephrectomy. Surveys were sent to the 58 fellowship training programs in the United States accredited by the American Society of Transplant Surgeons. RESULTS: The 32 responding programs performed approximately 40% of laparoscopic living donor nephrectomies in the United States in 2005. We found that almost all centers used a donor committee to screen candidates, enforce a body mass index cutoff, and use right kidneys when necessary and left kidneys in women of childbearing age. Regarding laparoscopic access, pure laparoscopy was favored 2 to 1 over the hand assisted technique and most of those who use nonbladed trocars do not close the fascia. Most surgeons divide the adrenal vein in left cases, use a vascular stapler on the renal artery and vein, and keep the ureter with the gonadal vein in the specimen. At most centers heparin is given before controlling the vessels. Extraction in pure laparoscopic cases is usually performed using a preplaced entrapment bag through a modified Pfannenstiel incision. CONCLUSIONS: Our survey describes how most renal transplant centers with accredited fellowship programs in the United States approach laparoscopic living donor nephrectomy. Specifically trends are revealed regarding patient selection, laparoscopic access and surgical technique.