Digital Doppler-cancellation servo for ultra-stable optical frequency dissemination over fiber

Progress made in optical references, including ultra-stable Fabry-Perot cavities, optical frequency combs and optical atomic clocks, have driven the need for ultra-stable optical fiber networks. Telecom-wavelength ultra-pure optical signal transport has been demonstrated on distances ranging from the laboratory scale to the continental scale. In this manuscript, we present a Doppler-cancellation setup based on a digital phase-locked loop for ultra-stable optical signal dissemination over fiber. The optical phase stabilization setup is based on a usual heterodyne Michelson-interferometer setup, while the Software Defined Radio (SDR) implementation of the phase-locked loop is based on a compact commercial board embedding a field programmable gate array, analog-to-digital and digital-to-analog converters. Using three different configurations including an undersampling method, we demonstrate a 20 m long fiber link with residual fractional frequency instability as low as $10^{-18}$ at 1000 s, and an optical phase noise of $-70$ dBc/Hz at 1 Hz with a telecom frequency carrier.Comment: 11 pages, 6 figure

TRAITEMENT RADIOTHERAPIQUE DES TUMEURS LARYNGEES PAR SUPERVOLTAGE. ETUDE DES RESULTATS

87 patients with laryngeal carcinoma were treated by irradiation between 1963 - 1967, 80 with Cobalt and 7 by Betatron. The dose was 6700 to 7200 rads over a period of 6 to 7 weeks. Subglottic cancers comprised 61% and 50% were in grade T3 or T4. Thirty two patients were alive five years after treatment. Of the subglottic group 16(29%) were recurrence at five years. Laryngectomy was done in 10 of the 20 cases with local recurrence, and of these 3 survived five years. In the subglottic group, all the recurrences occurred within the first three years. An improvement in results is anticipated with an increase in the size of the fields irradiated. (Suggit - Queensland)SCOPUS: NotDefined.jinfo:eu-repo/semantics/publishe

The role of radiotherapy in the treatment of oropharyngeal epithelioma

The use of high level radiation has brought about undeniable progress in the treatment of numerous types of epithelioma of the oropharynx. In spite of this, while telecobalt therapy in particular appears to be used to the limit of its possibilities, the prognosis in these disorders remains dismal. Irradiation used as exclusive therapy and within the limits of fractionation of the more or less classic dosage, hardly offers the prospect of an efficacious curative treatment except for lesions. of small dimensions, in particular those of the lateral wall. In other cases, it is the leading palliative treatment. It is equally very efficacious in treating micrometastases in cervical ganglia; it is exceptional to find development of symptoms of adenopathy at this level following prophylactic irradiation at a moderate dosage. In cases of macroscopic adenopathy, only moderate manifestations can be eliminated by this means, with a success rate of around 60%; cervical evidement is consequently often indispensable. It must be borne in mind that these results may be improved by associating irradiation with surgery or chemotherapy.SCOPUS: NotDefined.jinfo:eu-repo/semantics/publishe

EXPERIENCE DE L'INSTITUT BORDET DANS LE TRAITEMENT DES EPITHELIOMAS DE L'OROPHARYNX

SCOPUS: NotDefined.jinfo:eu-repo/semantics/publishe

Human equilibrative nucleoside transporter 1 testing in pancreatic ductal adenocarcinoma: A comparison between murine and rabbit antibodies

Aims: The human equilibrative nucleoside transporter 1 (hENT1) expression level in pancreatic ductal adenocarcinoma (PDAC) may predict survival in gemcitabine-treated patients after resection. These results have been obtained with a murine anti-hENT1 antibody (10D7G2) that is not commercially available. Another antibody, which is rabbit-derived (SP120), appears to have no predictive value in local, advanced or metastatic PDAC. We aimed to study whether the two antibodies are equivalent. Methods and results: We compared hENT1 expression with both antibodies in resected PDAC. The results were correlated with overall survival (OS) following gemcitabine treatment. Tissues from two sets of patients (n = 147 each) were stained with SP120 by the use of different equipment, with an amplification technique being used for set 2. The rate of 'hENT1 high' cases was lower with SP120 (set 1, 7% versus 48%; set 2, 11% versus 38%). With the amplification technique, the rate of hENT1 high cases was globally similar between both antibodies. However, concordance between the antibodies was found in only 50% of cases. High hENT1 expression was predictive of OS only with 10D7G2 (hazard ratio 0.49; 95% confidence interval 0.24-0.98; P = 0.045). Conclusions: The two antibodies are not equivalent. Further prospective studies seem to be warranted before hENT1 testing for PDAC is used in daily practise.SCOPUS: ar.jFLWINinfo:eu-repo/semantics/publishe

A simple-architecture fibered transmission system for dissemination of high stability 100 MHz signals

International audienceWe report on the development of a simple-architecture fiber-based frequency distribution system used to transfer high frequency stability 100 MHz signals. This work is focused on the emitter and the receiver performances that allow the transmission of the radio-frequency signal over an optical fiber. The system exhibits a residual fractional frequency stability of 1 × 10-14 at 1 s integration time and in the low 10-16 range after 100 s. These performances are suitable to transfer the signal of frequency references such as those of a state-of-the-art hydrogen maser without any phase noise compensation scheme. As an application, we demonstrate the dissemination of such a signal through a 100 m long optical fiber without any degradation. The proposed setup could be easily extended for operating frequencies in the 10 MHz-1 GHz range

Molecular changes in pancreatic cancer: Implications for molecular targeting therapy

Pancreatic ductal adenocarcinoma has a high mortality rate, which is generally related to the initial diagnosis coming at late stage disease combined with a lack of effective treatment options. Gemcitabine has been the most commonly used drug over the past decade and is still the cornerstone of therapy in adjuvant and metastatic settings. Intrinsic or acquired resistance of tumours to gemcitabine is, however, a major clinical problem. New therapeutic strategies are urgently needed whereas we also need to identify new prognostic and predictive biomarkers. This article focuses on gemcitabine resistance, on the role of chemokines and chemokine receptors in pancreatic carcinoma initiation and progression, and on stellate cells as partners in crime with neoplastic epithelial cells.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Compact Ultra-Stable Laser

International audienceWe present an ultra-stable laser based on a compact Fabry-Perot cavity with a thermal noise limit expected at 2 × 10 15 in trems of fractional frequency stability. The 25 mm long cavity is housed in a cubic vacuum chamber with a volume of about 2.2 L. The measured phase noise is 3 dBrad2/Hz at 1 Hz with a simple optical set-up at 1542 nm

Photonic Generation of High Power, Ultrastable Microwave Signals by Vernier Effect in a Femtosecond Laser Frequency Comb

Abstract Optical frequency division of an ultrastable laser to the microwave frequency range by an optical frequency comb has allowed the generation of microwave signals with unprecedently high spectral purity and stability. However, the generated microwave signal will suffer from a very low power level if no external optical frequency comb repetition rate multiplication device is used. This paper reports theoretical and experimental studies on the beneficial use of the Vernier effect together with the spectral selective filtering in a double directional coupler add-drop optical fibre ring resonator to increase the comb repetition rate and generate high power microwaves. The studies are focused on two selective filtering aspects: the high rejection of undesirable optical modes of the frequency comb and the transmission of the desirable modes with the lowest possible loss. Moreover, the conservation of the frequency comb stability and linewidth at the resonator output is particularly considered. Accordingly, a fibre ring resonator is designed, fabricated, and characterized, and a technique to stabilize the resonator’s resonance comb is proposed. A significant power gain is achieved for the photonically generated beat note at 10 GHz. Routes to highly improve the performances of such proof-of-concept device are also discussed