Experimental demonstration of the supersonic-subsonic bifurcation in the circular jump: A hydrodynamic white hole

We provide an experimental demonstration that the circular hydraulic jump represents a hydrodynamic white hole or gravitational fountain (the time-reverse of a black hole) by measuring the angle of the Mach cone created by an object in the "supersonic" inner flow region. We emphasise the general character of this gravitational analogy by showing theoretically that the white hole horizon constitutes a stationary and spatial saddle-node bifurcation within dynamical-systems theory. We also demonstrate that the inner region has a "superluminal" dispersion relation, i.e., that the group velocity of the surface waves increases with frequency, and discuss some possible consequences with respect to the robustness of Hawking radiation. Finally, we point out that our experiment shows a concrete example of a possible "transplanckian distortion" of black/white holes.Comment: 5 pages, 5 figures. New "transplanckian effect" described. Several clarifications, additional figures and references. Published versio

Proximal ischemia is a frequent cause of exercise-induced pain in patients with a normal ankle to brachial index at rest

BACKGROUND: Excluding a vascular origin of exercise-related pain is often difficult in clinical practice. Recent papers have underlined the frequent association of concurrent lumbar spine degenerative disease and peripheral arterial disease. Furthermore, even when suspected, isolated exercise-induced proximal ischemia is difficult to diagnose. Measurement of transcutaneous oxygen pressure (tcpO2) is an interesting and accurate method to differentiate proximal (buttock) from distal (calf) regional blood flow impairment (RBFI) during exercise. OBJECTIVES: We searched for isolated proximal-without-distal RBFI as a possible cause of claudication, in patients with borderline (ABI-b: 0.91 - 0.99) or normal (ABI-n: 1.00 to 1.40) ankle to brachial index at rest. STUDY DESIGN: Retrospective cohort design study. We analyzed patients referred to our laboratory with symptom limiting claudication and an ankle brachial index within normal limits. SETTING: University-based exercise-investigation center. METHODS: Over a 12-year period, we identified 463 patients referred to our laboratory that had their lowest resting ABI between 0.90 and 1.40. The tcpO2 on chest, buttocks, and calves were recorded during treadmill walking tests (3.2 km/h, 10% slope) in 220 ABI-b and 243 ABI-n unique consecutive patients complaining of limiting claudication (each patient\u27s ABI was the lowest of the 2 legs). Limiting claudication was defined as the reported inability to walk 1 kilometer without stopping. A DROP index (limb tcpO2-changes minus chest tcpO2-changes from rest) below -15 mmHg was used to indicate a positive result (i.e. exercise-induced RBFI). RESULTS: Treadmill exercise showed evidence for proximal or distal RBFI, of at least one side, in 128 out of 220 patients (58.2%) and in 86 out of 243 (35.4%) patients with ABI-b and ABI-n, respectively. Isolated proximal-without-distal RBFI was found in 32 out of the 128 (25.0 %) positive tests in ABI-b and 32 out of the 86 (37.2%) positive tests in ABI-n patients. LIMITATIONS: Study limitations include the absence of systematic follow-up of diagnosed patients and absence of systematic search for cardio-respiratory co-morbid conditions. CONCLUSION: Isolated proximal-without distal RBFI is found in approximately one out of 7 patients complaining of symptom limiting claudication with a borderline or normal resting ABI. Exercise-tcpO2 may help to discriminate patients with arterial claudication that could benefit from invasive vascular investigations and procedures

Status of the low beta 0.07 cryomodules for SPIRAL2

International audienceThe status of the low beta cryomodules for SPIRAL2, supplied by the Irfu institute of CEA Saclay, is reported in this paper. We summarise in three parts the RF tests performed on the cavities in vertical cryostat, the RF power tests of the qualifying cryomodule performed in 2010 and the RF power tests performed in 2011 on the first cryomodule of the serie

Horizon effects for surface waves in wave channels and circular jumps

Surface waves in classical fluids experience a rich array of black/white hole horizon effects. The dispersion relation depends on the characteristics of the fluid (in our case, water and silicon oil) as well as on the fluid depth and the wavelength regime. In some cases, it can be tuned to obtain a relativistic regime plus high-frequency dispersive effects. We discuss two types of ongoing analogue white-hole experiments: deep water waves propagating against a counter-current in a wave channel and shallow waves on a circular hydraulic jump.Comment: 4 pages, 2 figs. To appear in: Proceedings of the Spanish Relativity Meeting (ERE2010

Outcome after supracricoid laryngectomies in the material of ENT Department, Poznan University of Medical Sciences

All patients with T1 and T2 laryngeal cancer should be treated with the intent to preserve the larynx. In T3 glottic low-volume tumors, larynx preservation is an appropriate standard treatment option. Supracricoid partial laryngectomy remains a reasonable alternative to radiotherapy for patients with T2–T3 glottic cancer. Prospective clinical study aims to evaluate the oncological results of supracricoid partial laryngectomy as a treatment for selected glottic and supraglottic carcinoma, and to determine the different prognostic factors that may influence local control and survival. In the period of 2000–2007, 145 patients were treated at the academic tertiary referral medical center: ENT Department, University of Medical Sciences, Poznán, Poland. The ages of the analyzed group of patients ranged from 23 to 79, with mean 56.5 age for men and 25 for women. All of the patients had biopsy proven squamous cell carcinoma. Of the 145 patients 82 had glottic cancer and 63 had supraglottic cancer. The patients were staged according to the 2003 edition of the TNM classification established by the AJCC. The pathological TNM classification was additionally taken into consideration. All patients were treated by means of supracricoid and transglottic partial laryngectomy. The type of supracricoid partial laryngectomy was based on tumor localization and extension. Four patients underwent cricohyoidopexy, 57 cricohyoidoepiglottopexy, 65 reconstruction modo Calearo, and 19 modo Sedlacek-Tucker. We performed 21 unilateral selective neck dissections and none bilateral. A nasogastric feeding tube was inserted in all patients, and removed in patients that regained proper swallowing. As a result, we took into consideration the oncological and functional results. Histopathological examination of the operating specimen revealed the presence of dysplasia or invasive carcinoma at the margins, or a close margin of less than 5 mm from the edge of the resection (16 cases). The metastases were found on the neck in three cases, predominantly in the level II (2 cases) and III (1 case). Metastasis was found in one patient that had undergone CHP, Sedlacek-Tucker, and Calearo, respectively. Five patients received postoperative radiotherapy. The decision to use adjuvant radiotherapy was based on the presence of invasive carcinoma at the resection margin and on the presence of multiple positive neck nodes or extracapsular spread of the disease. The Kaplan–Meier estimated 3- and 5-year overall survival rates in the group of 122 because 23 patients did not report for medical check-ups

SPIRAL2 RFQ prototype - First results

JACoW web site MOPCH103International audienceThe SPIRAL2 RFQ is designed to accelerate either 5 mA deuteron beam (Q/A=1/2) or a 1 mA of q/A=1/3 particle up to 0.75 MeV/A at 88 MHz. It is a CW machine which has to show stable operation, provide the required availability and reduce losses to a minimum in order to minimize the activation constraints. Extensive modelisation was done to ensure a good vane position under RF. The prototype of this 4-vane RFQ was built and tested in INFN-LNS Catania and then in IN2P3-LPSC Grenoble. It allowed us to measure the vacuum quality, the RF field by X-ray measurements, the cavity displacement and the real vane displacement during the RF injection. Different techniques were used, including an innovative CCD measurement with a 0.8 μm precision. This paper outlines the different results

The GANIL control system as seen from the control room

http://accelconf.web.cern.ch/AccelConf/c81/papers/fp-08.pdfInternational audienc

Experimental study of a positive surge. Part 1: Basic flow patterns and wave attenuation

A positive surge results from a sudden change in flow that increases the depth. It is the unsteady flow analogy of the stationary hydraulic jump and a geophysical application is the tidal bore. Positive surges are commonly studied using the method of characteristics and the Saint-Venant equations. The paper presents the results from new experimental investigations conducted in a large rectangular channel. Detailed unsteady velocity measurements were performed with a high temporal resolution using acoustic Doppler velocimetry and non-intrusive free-surface measurement devices. Several experiments were conducted with the same initial discharge (Q=0.060 m³/s) and 6 different gate openings after closure resulting in both non-breaking undular and breaking bores. The analysis of undular surges revealed wave amplitude attenuation with increasing distance of surge propagation were in agreement with Ippen and Kulin theory. Also, undular wave period and wave length data were relatively close to the values predicted by the wave dispersion theory for gravity waves in intermediate water depths