Wide-band polarization controller for Si photonic integrated circuits.

A circuit for the management of any arbitrary polarization state of light is demonstrated on an integrated silicon (Si) photonics platform. This circuit allows us to adapt any polarization into the standard fundamental TE mode of a Si waveguide and, conversely, to control the polarization and set it to any arbitrary polarization state. In addition, the integrated thermal tuning allows kilohertz speed which can be used to perform a polarization scrambler. The circuit was used in a WDM link and successfully used to adapt four channels into a standard Si photonic integrated circuit.

Complex effective index in graphene-silicon waveguides.

We report for the first time and characterize experimentally the complex optical conductivity of graphene on silicon photonic waveguides. This permits us to predict accurately the behavior of photonic integrated devices encompassing graphene layers. Exploiting a Si microring add/drop resonator, we show the effect of electrical gating of graphene on the complex effective index of the waveguide by measuring both the wavelength shift of the resonance and the change in the drop peak transmission. Due to electro-refractive effect of graphene a giant (>10-3) change in the effective index is demonstrated for the first time on Si photonics waveguides and this large effect will crucially impact performances and consumption of Si photonics devices. We confirmed the results by two independent experiments involving two different gating schemes: Si gating through the ridge waveguide, and polymer-electrolyte gating. Both the experiments demonstrate a very large phase effect in good agreement with numerical calculations. The reported results validate the Kubo model for the case of graphene-Si photonics interfaces and for propagation in this type of waveguide. This is fundamental for the next design and fabrication of future graphene-silicon photonics devices.

Laparoscopic debulking of bulky lymph nodes in women with cervical cancer: indication and surgical outcomes.

OBJECTIVE: To describe the technique and the surgical outcome of laparoscopic resection of bulky lymph nodes before adjuvant treatment. DESIGN: Prospective pilot study. SETTING: Gynaecological oncology cancer centre. POPULATION: From January 2006 to February 2008, 22 consecutive women presented with cervical cancer and bulky metastatic lymph nodes (>2 cm). METHODS: All women underwent resection of bulky lymph nodes by laparoscopy. A prospective record of the main surgical outcomes was performed. MAIN OUTCOME MEASURES: Safety and efficacy of laparoscopic resection of bulky lymph nodes, conversion to laparotomy, intra- and perioperative morbidity. RESULTS: All the operations were completed by laparoscopy. Median operative time was 197 minutes (range 180-320). Median blood loss was 60 cc (range 10-100), two women experienced complications: one thermal injury of the sciatic root provoking postoperative leg palsy and one chylous ascites. The woman with the thermal injury has recovered most leg function with physiotherapy and the woman with chylous ascites recovered within 2 weeks, slightly delaying the adjuvant treatment. All women were discharged within 4 days from the operation (range 2-4). Pathology reports confirmed the presence of tumour metastases and the lymph nodes size. The adjuvant treatment started at a median time of 12 days (range 3-22). CONCLUSION: Debulking of large pelvic and para-aortic lymph nodes was effectively accomplished by laparoscopy in all 22 women with 9% complication rate. The surgical outcome is similar to historical series on women operated on by laparotomy, with the advantage of a faster recovery and an early start of adjuvant treatment.

The cholesterol requirement for sindbis virus entry and exit and characterization of a spike protein region involved in cholesterol dependence.

Semliki Forest virus (SFV) and Sindbis virus (SIN) are enveloped alphaviruses that enter cells via low-pH-triggered fusion in the endocytic pathway and exit by budding from the plasma membrane. Previous studies with cholesterol-depleted insect cells have shown that SFV requires cholesterol in the cell membrane for both virus fusion and efficient exit of progeny virus. An SFV mutant, srf-3, shows efficient fusion and exit in the absence of cholesterol due to a single point mutation in the E1 spike subunit, proline 226 to serine. We have here characterized the role of cholesterol in the entry and exit of SIN, an alphavirus quite distantly related to SFV. Growth, primary infection, fusion, and exit of SIN were all dramatically inhibited in cholesterol-depleted cells compared to control cells. Based on sequence differences within the E1 226 region between SFV, srf-3, and SIN, we constructed six SIN mutants with alterations within this region and characterized their cholesterol dependence. A SIN mutant, SGM, that had the srf-3 amino acid sequence from E1 position 224 to 235 showed increases of approximately 100-fold in infection and approximately 250-fold in fusion with cholesterol-depleted cells compared with infection and fusion of wild-type SIN. Pulse-chase analysis demonstrated that SGM exit from cholesterol-depleted cells was markedly more efficient than that of wild-type SIN. Thus, similar to SFV, SIN was cholesterol dependent for both virus entry and exit, and the cholesterol dependence of both steps could be modulated by sequences within the E1 226 region.