4,028 research outputs found

    Timing Signals and Radio Frequency Distribution Using Ethernet Networks for High Energy Physics Applications

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    Timing networks are used around the world in various applications from telecommunications systems to industrial processes, and from radio astronomy to high energy physics. Most timing networks are implemented using proprietary technologies at high operation and maintenance costs. This thesis presents a novel timing network capable of distributed timing with subnanosecond accuracy. The network, developed at CERN and codenamed “White- Rabbit”, uses a non-dedicated Ethernet link to distribute timing and data packets without infringing the sub-nanosecond timing accuracy required for high energy physics applications. The first part of this thesis proposes a new digital circuit capable of measuring time differences between two digital clock signals with sub-picosecond time resolution. The proposed digital circuit measures and compensates for the phase variations between the transmitted and received network clocks required to achieve the sub-nanosecond timing accuracy. Circuit design, implementation and performance verification are reported. The second part of this thesis investigates and proposes a new method to distribute radio frequency (RF) signals over Ethernet networks. The main goal of existing distributed RF schemes, such as Radio-Over-Fibre or Digitised Radio-Over-Fibre, is to increase the bandwidth capacity taking advantage of the higher performance of digital optical links. These schemes tend to employ dedicated and costly technologies, deemed unnecessary for applications with lower bandwidth requirements. This work proposes the distribution of RF signals over the “White-Rabbit” network, to convey phase and frequency information from a reference base node to a large numbers of remote nodes, thus achieving high performance and cost reduction of the timing network. Hence, this thesis reports the design and implementation of a new distributed RF system architecture; analysed and tested using a purpose-built simulation environment, with results used to optimise a new bespoke FPGA implementation. The performance is evaluated through phase-noise spectra, the Allan-Variance, and signalto- noise ratio measurements of the distributed signals

    Effects of therapeutic and aerobic exercise programs in temporomandibular disorder-associated headaches

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    Objective: To assess the effects of three 8-week exercise programs on the frequency, intensity, and impact of headaches in patients with headache attributed to temporomandibular disorder (TMD). Methodology: Thirty-six patients diagnosed with headache attributed to TMD participated in the study and were divided into three groups of 12 patients: a therapeutic exercise program (G1, mean age: 26.3±5.6 years), a therapeutic and aerobic exercise program (G2, mean age: 26.0±4.6 years), and an aerobic exercise program (G3, 25.8±2.94 years). Headache frequency and intensity were evaluated using a headache diary, and the adverse headache impact was evaluated using the Headache Impact Test (HIT-6). The intensity was reported using the numerical pain rating scale. These parameters were evaluated twice at baseline (A01/A02), at the end of the 8-week intervention period (A1), and 8-12 weeks after the end of the intervention (A2). Results: At A1, none of the G2 patients reported having headaches, in G1, only two patients reported headaches, and in G3, ten patients reported headache. The headache intensity scores (0.3 [95% CI: -0.401, 1.068]), (0.0 [95% CI: -0.734, 0.734]) and HIT-6 (50.7 [95% CI: 38.008, 63.459]), (49.5 [95% CI: 36.808, 62.259]), significantly decreased in G1 and G2 at A1. At A2 headache intensity scores (0.5 [95% CI: -0.256, 1.256]), (0.0 [95% CI: -0.756, 0.756]) and HIT-6 (55.1 [95% CI: 42.998, 67.268]), (51.7 [95% CI: 39.532, 63.802]) in G1 and G2 haven't change significantly. The effects obtained immediately after the completion of the intervention programs were maintained until the final follow-up in all groups. Conclusion: The programs conducted by G1 (therapeutic exercises) and G2 (therapeutic and aerobic exercise) had significant results at A1 and A2.info:eu-repo/semantics/publishedVersio

    Aortic root enlargement does not increase the surgical risk and short-term patient outcome

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    Objective: To analyze the short-term outcome of aortic root enlargement (ARE) using death and adverse events as end points. Methods: From January 1999 through December 2009, 3339 patients were subjected to aortic valve replacement (AVR). A total of 678 were considered to have small aortic roots (SARs) in which an aortic prosthesis size 21mm or smaller was implanted. ARE using a bovine pericardial patch was performed in another 218 patients, who constitute the study population. This comprised 174 females (79.8%); the mean age was 69.4±13.4 years (8-87, median 74 years), the body surface area (BSA) was 1.59±0.15m(2) and the body mass index (BMI) 25.77±3.16kgm(-2), and 192 (88.5%) were in New York Heart Association (NYHA) II-III. Preoperative echocardiography revealed significant left ventricular (LV) dysfunction in 17 patients (8%), a mean aortic valve area of 0.57±0.27cm(2), and a mean gradient of 62.51±21.25mmHg. A septal myectomy was performed in 129 subjects (59.2%), and other associated procedures, mostly coronary artery bypass grafting (CABG), in 60 (27.5%). Bioprostheses were implanted in 161 patients (73.9%). The mean valve size was 21.9±1.0 (21-25). The mean extracorporeal circulation (ECC) and aortic clamping times were 82.8±19.8min and 56.8±12.5min, respectively. Results: Hospital mortality was 0.9% (n=2) for ARE as compared with 0.6% (n=4) for the SAR group (p=0.8). Inotropic support was required in only 13 (5.9%) patients and the first 24-h chest drainage was 336.2±202ml. Other complications included pacemaker implantation (7.8%), acute renal failure (10.6%), respiratory (4.1%), and CVA/transient ischemic attack (CVA/TIA) (3.2%). Postoperative echocardiographic evaluation showed a significant decrease in peak and mean aortic gradients (23.7±9.5 and 14±6.2mmHg, respectively, p<0.0001). The mean indexed effective orifice area (iEOA) was 0.92±0.01cm(2)m(-2) (vs 0.84±0.07cm(2)m(-2), in SAR, p<0.0001). Only 11% of patients (n=24) with ARE exhibited moderate patient-prosthesis mismatch (PPM) and none had severe PPM. Mean hospital stay was 9.7±9.29 days (median 7 days). Conclusions: With the growing number of patients with degenerative aortic valve pathology, mainly an older population, sometimes with calcified and fragile aortic wall, the issue of dealing with an SAR poses the dilemma of whether to implant a smaller prosthesis and admit some degree of PPM, or to enlarge the aortic root. This study demonstrates that the latter can be done in a safe and reproducible manner
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