967 resultados para Low frequency


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Funding • The pooled data coordination team (PBoffetta, MH, YCAL) were supported by National Cancer Institute grant R03CA113157 and by National Institute of Dental and Craniofacial Research grant R03DE016611 • The Milan study (CLV) was supported by the Italian Association for Research on Cancer (Grant no. 10068). • The Aviano study (LDM) was supported by a grant from the Italian Association for Research on Cancer (AIRC), Italian League Against Cancer and Italian Ministry of Research • The Italy Multicenter study (DS) was supported by the Italian Association for Research on Cancer (AIRC), Italian League Against Cancer and Italian Ministry of Research. • The Study from Switzerland (FL) was supported by the Swiss League against Cancer and the Swiss Research against Cancer/Oncosuisse [KFS-700, OCS-1633]. • The central Europe study (PBoffetta, PBrenan, EF, JL, DM, PR, OS, NS-D) was supported by the World Cancer Research Fund and the European Commission INCOCOPERNICUS Program [Contract No. IC15- CT98-0332] • The New York multicentre study (JM) was supported by a grant from National Institute of Health [P01CA068384 K07CA104231]. • The study from the Fred Hutchison Cancer Research Center from Seattle (CC, SMS) was supported by a National Institute of Health grant [R01CA048996, R01DE012609]. • The Iowa study (ES) was supported by National Instituteof Health [NIDCR R01DE011979, NIDCR R01DE013110, FIRCA TW001500] and Veterans Affairs Merit Review Funds. • The North Carolina studies (AFO) were supported by National Institute of Health [R01CA061188], and in part by a grant from the National Institute of Environmental Health Sciences [P30ES010126]. • The Tampa study (PLazarus, JM) was supported by National Institute of Health grants [P01CA068384, K07CA104231, R01DE013158] • The Los Angeles study (Z-F Z, HM) was supported by grants from National Institute of Health [P50CA090388, R01DA011386, R03CA077954, T32CA009142, U01CA096134, R21ES011667] and the Alper Research Program for Environmental Genomics of the UCLA Jonsson Comprehensive Cancer Center. • The Houston study (EMS, GL) was supported by a grant from National Institute of Health [R01ES011740, R01CA100264]. • The Puerto Rico study (RBH, MPP) was supported by a grant from National Institutes of Health (NCI) US and NIDCR intramural programs. • The Latin America study (PBoffetta, PBrenan, MV, LF, MPC, AM, AWD, SK, VW-F) was supported by Fondo para la Investigacion Cientifica y Tecnologica (FONCYT) Argentina, IMIM (Barcelona), Fundaco de Amparo a‘ Pesquisa no Estado de Sao Paulo (FAPESP) [No 01/01768-2], and European Commission [IC18-CT97-0222] • The IARC multicentre study (SF, RH, XC) was supported by Fondo de Investigaciones Sanitarias (FIS) of the Spanish Government [FIS 97/ 0024, FIS 97/0662, BAE 01/5013], International Union Against Cancer (UICC), and Yamagiwa-Yoshida Memorial International Cancer Study Grant. • The Boston study (KKelsey, MMcC) was supported by a grant from National Institute of Health [R01CA078609, R01CA100679]. • The Rome study (SB, GC) was supported by AIRC (Italian Agency for Research on Cancer). • The US multicentre study (BW) was supported by The Intramural Program of the National Cancer Institute, National Institute of Health, United States. • The Sao Paolo study (V W-F) was supported by Fundacao de Ampara a Pesquisa no Estado de Sao Paulo (FAPESP No 10/51168-0) • The MSKCC study (SS, G-P Y) was supported by a grant from National Institute of Health [R01CA051845]. • The Seattle-Leo stud (FV) was supported by a grant from National Institute of Health [R01CA030022] • The western Europe Study (PBoffetta, IH, WA, PLagiou, DS, LS, FM, CH, KKjaerheim, DC, TMc, PT, AA, AZ) was supported by European Community (5th Frame work Programme) grant no QLK1-CT-2001- 00182. • The Germany Heidelberg study (HR) was supported by the grant No. 01GB9702/3 from the German Ministry of Education and Research.

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Because of high efficacy, long lifespan, and environment-friendly operation, LED lighting devices become more and more popular in every part of our life, such as ornament/interior lighting, outdoor lightings and flood lighting. The LED driver is the most critical part of the LED lighting fixture. It heavily affects the purchasing cost, operation cost as well as the light quality. Design a high efficiency, low component cost and flicker-free LED driver is the goal. The conventional single-stage LED driver can achieve low cost and high efficiency. However, it inevitably produces significant twice-line-frequency lighting flicker, which adversely affects our health. The conventional two-stage LED driver can achieve flicker-free LED driving at the expenses of significantly adding component cost, design complexity and low the efficiency. The basic ripple cancellation LED driving method has been proposed in chapter three. It achieves a high efficiency and a low component cost as the single-stage LED driver while also obtaining flicker-free LED driving performance. The basic ripple cancellation LED driver is the foundation of the entire thesis. As the research evolving, another two ripple cancellation LED drivers has been developed to improve different aspects of the basic ripple cancellation LED driver design. The primary side controlled ripple cancellation LED driver has been proposed in chapter four to further reduce cost on the control circuit. It eliminates secondary side compensation circuit and an opto-coupler in design while at the same time maintaining flicker-free LED driving. A potential integrated primary side controller can be designed based on the proposed LED driving method. The energy channeling ripple cancellation LED driver has been proposed in chapter five to further reduce cost on the power stage circuit. In previous two ripple cancellation LED drivers, an additional DC-DC converter is needed to achieve ripple cancellation. A power transistor has been used in the energy channeling ripple cancellation LED driving design to successfully replace a separate DC-DC converter and therefore achieved lower cost. The detailed analysis supports the theory of the proposed ripple cancellation LED drivers. Simulation and experiment have also been included to verify the proposed ripple cancellation LED drivers.

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We report on a series of Spanish patients with acute lymphoblastic leukaemia in whom the t(12;21) [TEL/AML1] translocation could not be identified with two sensitive techniques: reverse transcript-polymerase chain reaction (RT-PCR) and fluorescence in-situ hybridization (FISH). 101 cases were analysed: 38 children (29 B-cell precursor; nine T-cell precursor) and 63 adults (48 B-cell precursor; 15 T-cell precursor). Specific RT-PCR to amplify the TEL/AML1 fusion transcript was negative in all 101 cases. Moreover, all 38 paediatric samples were also negative by interphase FISH analysis for the presence of the TEL/AML1 fusion. These results suggest the existence of geographic/race variations in the genotype of acute lymphoblastic leukaemia (ALL).

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To explain the missing heritability after the genome-wide association studies era, sequencing studies allow the identification of low-frequency variants with a stronger effect on disease risk. Common variants in the interleukin 10 gene (IL10) have been consistently associated with Behçet's disease (BD) and the goal of this study is to investigate the role of low-frequency IL10 variants in BD susceptibility.

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We have conducted a mini-survey for low-frequency radio emission from some of the closest brown dwarfs to the Sun with rapid rotation rates: SIMP J013656.5 +093347, WISEPC 150649.97+702736.0, and WISEPA J174124.26+255319.5.We have placed robust 3s upper limits on the flux density in the 111 – 169 MHz frequency range for these targets: WISE 1506: < 0:72 mJy; WISE 1741: < 0:87 mJy; SIMP 0136: < 0:66 mJy. At 8 hours of integration per target to achieve these limits, we find that systematic and detailed study of this class of object at LOFAR frequencies will require a substantial dedication of resources.

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Erratum in: Low-frequency and common genetic variation in ischemic stroke: The METASTROKE collaboration. [Neurology. 2016]

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Background: Vibroacoustic disease (VAD) is a systematic pathology characterized by the abnormal growth of extra-cellular matrices in the absence of infl ammatory processes, namely collagen and elastin, both of which are abundant in the basement membrane zone of the vocal folds. VAD can develop due to long-term exposure to infrasound and low-frequency noise (ILFN, <500 Hz). Mendes et al. (2006, 2008 and 2012) revealed that ILFN-exposed males and females presented an increased fundamental frequency (F0), decreased jitter %, and reduced maximum phonation frequency range, when compared with normative data. Temporal measures of maximum phonation time and S/Z ratio were generally reduced. Study Aims: Herein, the same voice acoustic parameters of 48 males, 36 airline pilots and 12 cabin crewmembers (age range 25-60 years) were studied, and the effects and interaction of age and years of ILFN exposure were investigated within those parameters. ILFN-exposure time (i.e. years of professional activity) ranged from 3.5 to 36 years. Materials and Methods: Spoken and sung phonatory tasks were recorded with a DA-P1 Tascam DAT and a C420III PP AKG head-worn microphone, positioned at 3 cm from the mouth. Acoustic analyses were performed using KayPENTAX Computer Speech Lab and Multi-Dimensional Voice Program. Results: Results revealed that even though pilots and cabin crewmembers were exposed to occupational environments with distinct (ILFN-rich) acoustical frequency distributions and sound pressure levels, differences in the vocal acoustic parameters were not evident. Analyzing data from both professional groups (N = 48) revealed that F0 increased signifi cantly with the number of years of professional activity. Conclusion: These results strongly suggest that the number of years of professional activity (i.e. total ILFN exposure time) had a signifi cant effect on F0. Furthermore, they may refl ect the histological changes specifi cally observed on the vocal folds of ILFN-exposed professionals.

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Size and shape tuneable ZnO nanostructures were prepared by a low frequency ultrasound (42 kHz) route using various organic solvents as the reaction media. The crystalline nature, lattice parameters and microstructural parameters such as microstrain, stress and energy density of the prepared ZnO nanostructures were revealed through X-ray diffraction (XRD) analysis. The organic solvents influenced the size and morphology of the ZnO nanostructures, and interesting morphological changes involving a spherical to triangular shaped transition were observed. The visible emission properties and lattice vibrational characteristics of the nanostructures were drastically modified by the changes in size and shape. Raman spectral measurements revealed the presence of multiphonon processes in the ZnO nanostructures. The intensity of the visible emission band was found to vary with the size and morphology of the structures. The strongest visible emission band corresponded to the structure with the largest surface/volume ratio and could be attributed to surface oxygen vacancies. The control over the size and morphology of ZnO nanostructures has been presented as a means of determining the intensity of the visible emission band

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The low-frequency electromagnetic compatibility (EMC) is an increasingly important aspect in the design of practical systems to ensure the functional safety and reliability of complex products. The opportunities for using numerical techniques to predict and analyze system’s EMC are therefore of considerable interest in many industries. As the first phase of study, a proper model, including all the details of the component, was required. Therefore, the advances in EMC modeling were studied with classifying analytical and numerical models. The selected model was finite element (FE) modeling, coupled with the distributed network method, to generate the model of the converter’s components and obtain the frequency behavioral model of the converter. The method has the ability to reveal the behavior of parasitic elements and higher resonances, which have critical impacts in studying EMI problems. For the EMC and signature studies of the machine drives, the equivalent source modeling was studied. Considering the details of the multi-machine environment, including actual models, some innovation in equivalent source modeling was performed to decrease the simulation time dramatically. Several models were designed in this study and the voltage current cube model and wire model have the best result. The GA-based PSO method is used as the optimization process. Superposition and suppression of the fields in coupling the components were also studied and verified. The simulation time of the equivalent model is 80-100 times lower than the detailed model. All tests were verified experimentally. As the application of EMC and signature study, the fault diagnosis and condition monitoring of an induction motor drive was developed using radiated fields. In addition to experimental tests, the 3DFE analysis was coupled with circuit-based software to implement the incipient fault cases. The identification was implemented using ANN for seventy various faulty cases. The simulation results were verified experimentally. Finally, the identification of the types of power components were implemented. The results show that it is possible to identify the type of components, as well as the faulty components, by comparing the amplitudes of their stray field harmonics. The identification using the stray fields is nondestructive and can be used for the setups that cannot go offline and be dismantled

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This paper reports on a low frequency piezoelectric energy harvester that scavenges energy from a wire carrying an AC current. The harvester is described, fabricated and characterized. The device consists of a silicon cantilever with integrated piezoelectric capacitor and proof-mass that incorporates a permanent magnet. When brought close to an AC current carrying wire, the magnet couples to the AC magnetic field from a wire, causing the cantilever to vibrate and generate power. The measured average power dissipated across an optimal resistive load was 1.5 μW. This was obtained by exciting the device into mechanical resonance using the electro-magnetic field from the 2 A source current. The measurements also reveal that the device has a nonlinear response that is due to a spring hardening mechanism.

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Diffuse radio emission in galaxy clusters has been observed with different size and properties. Giant radio halos (RH), Mpc-size sources found in merging clusters, and mini halos (MH), 0.1-0.5 Mpc size sources located in relaxed cool-core clusters, are thought to be distinct classes of objects with different formation mechanisms. However, recent observations have revealed the unexpected presence of diffuse emission on Mpc-scales in relaxed clusters that host a central MH and show no signs of major mergers. The study of these sources is still at the beginning and it is not yet clear what could be the origin of their unusual emission. The main goal of this thesis is to test the occurrence of these peculiar sources and investigate their properties using low frequency radio observations. This thesis consists in the study of a sample of 12 cool-core galaxy clusters which present some level of dynamical disturbances on large-scale. The heterogeneity of sources in the sample allowed me to investigate under which conditions a halo-type emission is present in MH clusters; and also to study the connection between AGN bubbles and the local environment. Using high sensitivity LOFAR observations, I have detected large-scale emission in four non-merging clusters, in addition to the central MH. I have constrained for the first time the spectral properties of diffuse emission in these double radio component galaxy clusters, and I have investigated the connection between their thermal and non-thermal emission for a better comprehension of the acceleration mechanism. Furthermore, I derived upper limits to the halo power for the other clusters in the sample, which could present large-scale diffuse emission under the detection threshold. Finally, I have reconstructed the duty-cycle of one of the most powerful AGN known, located at the centre of a galaxy cluster of the sample.

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The purpose of this study was to investigate the effects of a short-term low-or high-carbohydrate (CHO) diet consumed after exercise on sympathetic nervous system activity. Twelve healthy males underwent a progressive incremental test; a control measurement of plasma catecholamines and heart rate variability (HRV); an exercise protocol to reduce endogenous CHO stores; a low-or high-CHO diet (counterbalanced order) consumed for 2 days, beginning immediately after the exercise protocol; and a second resting plasma catecholamine and HRV measurement. The exercise and diet protocols and the second round of measurements were performed again after a 1-week washout period. The mean (+/- SD) values of the standard deviation of R-R intervals were similar between conditions (control, 899.0 +/- 146.1 ms; low-CHO diet, 876.8 +/- 115.8 ms; and high-CHO diet, 878.7 +/- 127.7 ms). The absolute high-and low-frequency (HF and LF, respectively) densities of the HRV power spectrum were also not different between conditions. However, normalized HF and LF (i.e., relative to the total power spectrum) were lower and higher, respectively, in the low-CHO diet than in the control diet (mean +/- SD, 17 +/- 9 normalized units (NU) and 83 +/- 9 NU vs. 27 +/- 11 NU and 73 +/- 17 NU, respectively; p < 0.05). The LF/HF ratio was higher with the low-CHO diet than with the control diet (mean +/- SD, 7.2 +/- 6.2 and 4.2 +/- 3.2, respectively; p < 0.05). The mean values of plasma catecholamines were not different between diets. These results suggest that the autonomic control of the heart rate was modified after a short-term low-CHO diet, but plasma catecholamine levels were not altered.

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The aim of this study was to examine the effects of low carbohydrate (CHO) availability on heart rate variability (HRV) responses during moderate and severe exercise intensities until exhaustion. Six healthy males (age, 26.5 +/- 6.7 years; body mass, 78.4 +/- 7.7 kg; body fat %, 11.3 +/- 4.5%; (V) over dotO(2max), 39.5 +/- 6.6 mL kg(-1) min(-1)) volunteered for this study. All tests were performed in the morning, after 8-12 h overnight fasting, at a moderate intensity corresponding to 50% of the difference between the first (LT(1)) and second (LT(2)) lactate breakpoints and at a severe intensity corresponding to 25% of the difference between the maximal power output and LT(2). Forty-eight hours before each experimental session, the subjects performed a 90-min cycling exercise followed by 5-min rest periods and subsequent 1-min cycling bouts at 125% (V) over dotO(2max) (with 1-min rest periods) until exhaustion, in order to deplete muscle glycogen. A diet providing 10% (CHO(low)) or 65% (CHO(control)) of energy as carbohydrates was consumed for the following 2 days until the experimental test. The Poicare plots (standard deviations 1 and 2: SD1 and SD2, respectively) and spectral autoregressive model (low frequency LF, and high frequency HF) were applied to obtain HRV parameters. The CHO availability had no effect on the HRV parameters or ventilation during moderate-intensity exercise. However, the SD1 and SD2 parameters were significantly higher in CHO(low) than in CHO(control), as taken at exhaustion during the severe-intensity exercise (P < 0.05). The HF and LF frequencies (ms(2)) were also significantly higher in CHO(low) than in CHO(control) (P < 0.05). In addition, ventilation measured at the 5 and 10-min was higher in CHO(low) (62.5 +/- 4.4 and 74.8 +/- 6.5 L min(-1), respectively, P < 0.05) than in CHO(control) (70.0 +/- 3.6 and 79.6 +/- 5.1 L min(-1), respectively; P < 0.05) during the severe-intensity exercise. These results suggest that the CHO availability alters the HRV parameters during severe-, but not moderate-, intensity exercise, and this was associated with an increase in ventilation volume.

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The present study details new turbulence field measurements conducted continuously at high frequency for 50 hours in the upper zone of a small subtropical estuary with semi-diurnal tides. Acoustic Doppler velocimetry was used, and the signal was post-processed thoroughly. The suspended sediment concentration wad further deduced from the acoustic backscatter intensity. The field data set demonstrated some unique flow features of the upstream estuarine zone, including some low-frequency longitudinal oscillations induced by internal and external resonance. A striking feature of the data set is the large fluctuations in all turbulence properties and suspended sediment concentration during the tidal cycle. This feature has been rarely documented.