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Mazeh, Tsevi, Yuval Krymolowski y David W. Latham. "Detection of Spectroscopic Triples". International Astronomical Union Colloquium 135 (1992): 161–63. http://dx.doi.org/10.1017/s0252921100006308.
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Several binary stars detected by the Center for Astrophysics (CfA) radial-velocity surveys were found to be members of triple systems. We present two examples, each requires a different analysis to discover its multiplicity.One example is G176-46, a double-lined halo star of the Carney & Latham (1987) high proper-motion survey. The secondary star (G176-46b) displays large radial velocity variations, in contrast with the primary (G176-46a), which is constant within the error limits. Figure 1 shows two cross correlations of the stellar spectra against the same calculated template taken at different times, which indicate that only the secondary’s peak changes its position. A similar variation was observed previously for ADS 8811 (Mazeh & Latham 1988).We have found the secondary radial velocity to vary with a period of 10.44 days, and therefore conclude that Gl76-46b is a member of a short-period binary system. The orbital solution has an amplitude of 38 km s−1 and eccentricity of 0.05.
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Tu, Jiaxun, Xingqun Zhan, Maolin Chen, Han Gao y Yuankang Chen. "GNSS intermediate spoofing detection via dual‐peak in frequency domain and relative velocity residuals". IET Radar, Sonar & Navigation 14, n.º 3 (10 de febrero de 2020): 439–47. http://dx.doi.org/10.1049/iet-rsn.2019.0366.
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Hata, Kohkichi, Toshiyuki Hata y Manabu Kitao. "Intratumoral peak systolic velocity as a new possible predictor for detection of adnexal malignancy". American Journal of Obstetrics and Gynecology 172, n.º 5 (mayo de 1995): 1496–500. http://dx.doi.org/10.1016/0002-9378(95)90485-9.
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Newman, Jennifer F., Valliappa Lakshmanan, Pamela L. Heinselman, Michael B. Richman y Travis M. Smith. "Range-Correcting Azimuthal Shear in Doppler Radar Data". Weather and Forecasting 28, n.º 1 (1 de febrero de 2013): 194–211. http://dx.doi.org/10.1175/waf-d-11-00154.1.
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Abstract The current tornado detection algorithm (TDA) used by the National Weather Service produces a large number of false detections, primarily because it calculates azimuthal shear in a manner that is adversely impacted by noisy velocity data and range-degraded velocity signatures. Coincident with the advent of new radar-derived products and ongoing research involving new weather radar systems, the National Severe Storms Laboratory is developing an improved TDA. A primary component of this algorithm is the local, linear least squares derivatives (LLSD) azimuthal shear field. The LLSD method incorporates rotational derivatives of the velocity field and is affected less strongly by noisy velocity data in comparison with traditional “peak to peak” azimuthal shear calculations. LLSD shear is generally less range dependent than peak-to-peak shear, although some range dependency is unavoidable. The relationship between range and the LLSD shear values of simulated circulations was examined to develop a range correction for LLSD shear. A linear regression and artificial neural networks (ANNs) were investigated as range-correction models. Both methods were used to produce fits for the simulated shear data, although the ANN excelled as it could capture the nonlinear nature of the data. The range-correction methods were applied to real radar data from tornadic and nontornadic events to measure the capacity of the corrected shear to discriminate between tornadic and nontornadic circulations. The findings presented herein suggest that both methods increased shear values during tornadic periods by nearly an order of magnitude, facilitating differentiation between tornadic and nontornadic scans in tornadic events.
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Li, Punan y Xiaoli Zhang. "Diagnostic Value and Clinical Performance of Cardiac Ultrasound in Patients with Chronic Heart Failure with Hypertension". Evidence-Based Complementary and Alternative Medicine 2022 (5 de mayo de 2022): 1–5. http://dx.doi.org/10.1155/2022/4238284.
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Objective. To assess the diagnostic value and clinical performance of cardiac ultrasound in patients with chronic heart failure and hypertension. Methods. In this prospective study, between August 2017 and January 2020, 50 patients with chronic heart failure and hypertension were recruited and assigned to the study group and 50 healthy individuals during the same period after physical examinations were included in the control group. Cardiac ultrasound examinations were performed on the participants, and the results were compared and analyzed. Results. The study group had a higher left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD), left ventricular ejection fraction (LVEF), and late diastolic peak flow velocity (A wave) and showed lower early diastolic peak flow velocity (E wave) and late diastolic peak flow velocity/lower early diastolic peak flow velocity (E/A) ratio levels than in the control group. The study group had 15 patients with grade I cardiac function (ultrasound detection rate of 100%), 18 patients with grade II cardiac function (ultrasound detection rate of 100%), and 17 patients with grade III cardiac function (ultrasound detection rate of 100%). Grade I cardiac function patients showed the lowest LVEDD, LVESD, and E/A and the highest LVEF than grade II patients, followed by grade III patients. The study group showed higher LVEF and echocardiographic estimation of the pulmonary arterial systolic pressure (PASP) and lower right ventricular lateral wall systolic excursion velocity and tricuspid annular plane systolic excursion (TAPSE) than the control group. Chronic heart failure with hypertension was associated with high levels of right atrial total emptying volume (RAVIt), right atrial passive emptying volume (RAVIp), right atrial active emptying volume (RAVIa), and right atrial active emptying fraction (RAVIaEF) and low levels of right atrial total emptying fraction (RAVItEF) and right atrial passive emptying fraction (RAVIpEF) versus the healthy status (all P < 0.05). Conclusion. Cardiac ultrasound is a noninvasive operation with low cost, high repeatability, and accurate detection, which can identify right heart function impairment at an early stage, assist clinical treatment, and improve patient prognosis, so it is worthy of promotion and application.
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Kuriki, Ayako, Hiroshi Yamagami, Kozue Saito, Shuichi Tonomura, Kazuki Fukuma, Takeshi Yoshimoto, Soichiro Abe et al. "Effects of calcification on the detection of internal carotid artery stenosis by peak systolic velocity". Japanese Journal of Stroke 41, n.º 3 (2019): 171–76. http://dx.doi.org/10.3995/jstroke.10636.
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Bullock, R., W. Martin, A. Coomarasamy y M. Kilby. "Detection of fetal anaemia: comparison of middle cerebral artery peak systolic velocity and liquor OD450". Journal of Obstetrics and Gynaecology 23, sup1 (enero de 2003): S10. http://dx.doi.org/10.1080/0144361031000092862.
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DIMITROULAS, THEODOROS, GEORGIOS GIANNAKOULAS, KLIO PAPADOPOULOU, HARALAMBOS KARVOUNIS, HARA DIMITROULA, GEORGIOS KOLIAKOS, THEODOROS KARAMITSOS, DESPOINA PARCHARIDOU y LOUKAS SETTAS. "Early Detection of Cardiac Involvement in Systemic Sclerosis Assessed by Tissue-Doppler Echocardiography: Relationship with Neurohormonal Activation and Endothelial Dysfunction". Journal of Rheumatology 37, n.º 5 (1 de marzo de 2010): 993–99. http://dx.doi.org/10.3899/jrheum.090931.
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Objective.Cardiopulmonary complications are common in patients with systemic sclerosis (SSc). We assessed cardiac involvement in patients with SSc using echocardiography and investigated the association of N-terminal pro-brain natriuretic peptide (NT-proBNP) and asymmetric dimethylarginine (ADMA) with echocardiographic measures of myocardial function in sera of patients with SSc who had no symptoms of heart failure.Methods.We prospectively studied 52 patients with SSc (mean age 55.7 ± 10.1 yrs, 51 women), with conventional and tissue-Doppler echocardiography. Plasma NT-proBNP and ADMA levels were measured in all patients. Data were compared with those obtained from 25 healthy controls comparable for age and sex.Results.Patients with SSc had impaired left ventricular (LV) and right ventricular diastolic function expressed by inverted ratio of peak early to peak late transmitral (Mit E/A) and transtricuspid velocity and increased left atrial diameter compared with controls. Peak systolic mitral lateral annular motion velocity and peak early diastolic mitral lateral annular motion velocity (LV Em) were lower, while LV E/Em ratio was higher, in patients with SSc compared to controls. ADMA was significantly related with LV Em and E/Em ratio. NT-proBNP was associated with Mit E, Mit E/A ratio and mitral deceleration time. Significant correlation was also observed between NT-proBNP and ADMA levels.Conclusion.Depressed cardiac function is common, even in asymptomatic patients with SSc. NT-proBNP and ADMA are significantly correlated with echocardiographic abnormalities, providing a potent link for cardiac function, neuroendocrine derangement, and endothelial dysfunction in patients with SSc who have cardiac disease.
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Crowder, Nathan A., Michael R. W. Dawson y Douglas R. W. Wylie. "Temporal Frequency and Velocity-Like Tuning in the Pigeon Accessory Optic System". Journal of Neurophysiology 90, n.º 3 (septiembre de 2003): 1829–41. http://dx.doi.org/10.1152/jn.00654.2002.
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Neurons in the accessory optic system (AOS) and pretectum are involved in the analysis of optic flow and the generation of the optokinetic response. Previous studies found that neurons in the pretectum and AOS exhibit direction selectivity in response to large-field motion and are tuned in the spatiotemporal domain. Furthermore, it has been emphasized that pretectal and AOS neurons are tuned to a particular temporal frequency, consistent with the “correlation” model of motion detection. We examined the responses of neurons in the nucleus of the basal optic root (nBOR) of the AOS in pigeons to large-field drifting sine wave gratings of varying spatial (SF) and temporal frequencies (TF). nBOR neurons clustered into two categories: “Fast” neurons preferred low SFs and high TFs, and “Slow” neurons preferred high SFs and low TFs. The fast neurons were tuned for TF, but the slow nBOR neurons had spatiotemporally oriented peaks that suggested velocity tuning (TF/SF). However, the peak response was not independent of SF; thus we refer to the tuning as “apparent velocity tuning” or “velocity-like tuning.” Some neurons showed peaks in both the fast and slow regions. These neurons were TF-tuned at low SFs, and showed velocity-like tuning at high SFs. We used computer simulations of the response of an elaborated Reichardt detector to show that both the TF-tuning and velocity-like tuning shown by the fast and slow neurons, respectively, may be explained by modified versions of the correlation model of motion detection.
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Morris, Nicholas A., Nathan Manning, Randolph S. Marshall, E. Sander Connolly, Jan Claassen, Sachin Agarwal, David J. Roh, J. Michael Schmidt y Soojin Park. "Transcranial Doppler Waveforms During Intra-aortic Balloon Pump Counterpulsation for Vasospasm Detection After Subarachnoid Hemorrhage". Neurosurgery 83, n.º 3 (21 de julio de 2017): 416–21. http://dx.doi.org/10.1093/neuros/nyx405.
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Abstract BACKGROUND Transcranial Doppler ultrasound is a standard screening tool for vasospasm after subarachnoid hemorrhage. Prevention of vasospasm-induced delayed cerebral ischemia after subarachnoid hemorrhage depends on optimization of cerebral perfusion pressure, which can be challenged by neurogenic stress cardiomyopathy. Intra-aortic balloon pumps have been utilized to augment cerebral perfusion, but they change the transcranial Doppler waveform, altering its interpretability for vasospasm screening. OBJECTIVE To assess the features of the transcranial Doppler waveform that correlate with vasospasm. METHODS We retrospectively reviewed cases of subarachnoid hemorrhage that underwent same-day transcranial Doppler ultrasound and angiography. Transcranial Doppler waveforms were assessed for mean velocity, peak systolic velocity, balloon pump-augmented diastolic velocity, and a novel feature, “delta velocity” (balloon pump-augmented velocity − systolic velocity). Relationship of flow velocity features to vasospasm was estimated by generalized estimating equation models using a Gaussian distribution and an exchangeable correlation structure. RESULTS There were 31 transcranial Doppler and angiography pairings (12 CT angiography/19 digital subtraction angiography) from 4 patients. Fourteen pairings had proximal vasospasm by angiography. Delta velocity was associated with proximal vasospasm (coefficient –6.8 [95% CI –9.8 to –3.8], P < .001). There was no significant correlation with proximal vasospasm for mean velocity (coefficient –13.0 [95% CI –29.3 to 3.4], P = .12), systolic velocity (coefficient –8.7 [95% CI –24.8 to 7.3], P = .29), or balloon pump-augmented velocity (coefficient –15.3 [95% CI –31.3 to 0.71], P = .06). CONCLUSION Delta velocity, a novel transcranial Doppler flow velocity feature, may reflect vasospasm in patients with subarachnoid hemorrhage and intra-aortic balloon pumps.
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Bhambhani, Yagesh N., Robert S. Burnham, Gary D. Wheeler, Peter Eriksson, Leona J. Holland y Robert D. Steadward. "Ventilatory Threshold during Wheelchair Exercise in Untrained and Endurance-Trained Subjects with Quadriplegia". Adapted Physical Activity Quarterly 12, n.º 4 (octubre de 1995): 333–43. http://dx.doi.org/10.1123/apaq.12.4.333.
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In this study we compared the ventilatory threshold (VT) between 8 untrained and 8 endurance-trained males with quadriplegia during simulated wheelchair exercise. Each subject completed an incremental velocity test in his personal wheelchair mounted on a customized roller system designed to provide velocity and distance feedback. VT was identified by two trained evaluators using established respiratory gas exchange criteria. A significant interevaluator reliability coefficient of .90 (p < .01) was observed for the detection of VT. Relative oxygen uptake (V̇O2, ml · kg-1 · min-1) at VT and peak V̇O2 were significantly (p < .05) higher in the endurance-trained compared to untrained subjects. However, no significant difference (p > .05) was observed between the two groups when VT was expressed as a percentage of peak V̇O2. Significant correlations of .86 and .81 (p < .01) were observed between VT and peak V̇O2 in the untrained and trained groups, respectively. It was concluded that endurance training improves both VT and peak V̇O2 during wheelchair exercise in male subjects with quadriplegia but does not improve VT when it is expressed relative to peak V̇O2.
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Kingfield, Darrel M. y James G. LaDue. "The Relationship between Automated Low-Level Velocity Calculations from the WSR-88D and Maximum Tornado Intensity Determined from Damage Surveys". Weather and Forecasting 30, n.º 5 (1 de octubre de 2015): 1125–39. http://dx.doi.org/10.1175/waf-d-14-00096.1.
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Abstract The relationship between automated low-level velocity derived from WSR-88D severe storm algorithms and two groups of tornado intensity were evaluated using a 4-yr climatology of 1975 tornado events spawned from 1655 supercells and 320 quasi-linear convective systems (QLCSs). A comparison of peak velocity from groups of detections from the Mesocyclone Detection Algorithm and Tornado Detection Algorithm for each tornado track found overlapping distributions when discriminating between weak [rated as category 0 or 1 on the enhanced Fujita scale (EF0 and EF1)] and strong (EF2–5) events for both rotational and delta velocities. Dataset thresholding by estimated affected population lowered the range of observed velocities, particularly for weak tornadoes while retaining a greater frequency of events for strong tornadoes. Heidke skill scores for strength discrimination were dependent on algorithm, velocity parameter, population threshold, and convective mode, and varied from 0.23 and 0.66. Bootstrapping the skill scores for each algorithm showed a wide range of low-level velocities (at least 7 m s−1 in width) providing an equivalent optimal skill at discriminating between weak and strong tornadoes. This ultimately limits identification of a single threshold for optimal strength discrimination but the results match closely with larger prior manual studies of low-level velocities.
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Geerts, L., J. N. Rossouw, A. C. Van Wyk y C. A. Wright. "Limitations of middle cerebral artery peak systolic velocity in the detection of severe anaemia: A case report". South African Journal of Obstetrics and Gynaecology 21, n.º 2 (14 de diciembre de 2015): 44. http://dx.doi.org/10.7196/sajog.898.
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Morita, Chiho, Takaaki Nakatsu, Shozo Kusachi, Tomoki Kitawaki, Shinichi Usui, Kazuo Tobe, Shinji Toyonaga, Hiroko Ogawa, Satoshi Hirohata y Yasushi Shiratori. "Development of an automatic Doppler flow signal detection system: variability of pulmonary and aortic peak flow velocity". Journal of Medical Ultrasonics 34, n.º 1 (15 de marzo de 2007): 37–42. http://dx.doi.org/10.1007/s10396-006-0126-7.
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Romanic, Djordje, Junayed Chowdhury, Jubayer Chowdhury y Horia Hangan. "Investigation of the Transient Nature of Thunderstorm Winds from Europe, the United States, and Australia Using a New Method for Detection of Changepoints in Wind Speed Records". Monthly Weather Review 148, n.º 9 (26 de agosto de 2020): 3747–71. http://dx.doi.org/10.1175/mwr-d-19-0312.1.
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Abstract This paper investigates the transient characteristics in 41 velocity records of 19 thunderstorm events from around the world—9 from Europe, 9 from the United States, and 1 from Australia. The transient features of thunderstorm winds were examined by introducing an objective method for the detection of changepoints in the time series. The methodology divides velocity records into segments characterized by different statistical properties. The segmentation is based on the following properties of the isolated segments: mean (M) and the standard deviation (SD). This study demonstrated that the maximum velocity during the thunderstorm peak in the events from Europe is typically 2–4 times larger than the mean wind speed before the thunderstorm. The duration of the thunderstorm velocity peak was 2–5 min in approximately 60% of the analyzed records using the M statistic and 5–10 min when analyzed using the SD statistic. Therefore, the velocity fluctuations caused by thunderstorm winds last longer than the abrupt changes in the mean wind field. Similarly, the ramp-up time was longer when the records were analyzed using the SD statistic. The segmentation methodology was tested for different duration of velocity records and using data with different sampling frequencies. The performances of the introduced method were compared against the results of two other segmentation procedures proposed in the literature. One of the practical applications of this method is the physical separation between the thunderstorm and nonthunderstorm components of a wind event. Significance Statement Thunderstorm outflow winds are short-lived phenomena produced by cold downdrafts that originate in thunderstorm clouds. This study analyzes the transient nature of thunderstorm winds from Europe, the United States, and Australia using a segmentation method applied to anemometer velocity records. This segmentation method identifies abrupt changes of mean wind speed and wind fluctuations in the velocity data. This research provides the means of isolating different segments within the thunderstorm wind records in an objective way that is based on rigorous mathematical principles. The proposed method can automatically distinguish thunderstorm from nonthunderstorm winds. The peak velocities in thunderstorm outflows are 2–4 times the mean wind speed before the thunderstorm. The most intense episodes of thunderstorm winds usually last 2–5 min.
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Mariak, Zenon, Jaroslaw Krejza, Miroslaw Swiercz, Kazimierz Kordecki y Janusz Lewko. "Accuracy of transcranial color Doppler ultrasonography in the diagnosis of middle cerebral artery spasm determined by receiver operating characteristic analysis". Journal of Neurosurgery 96, n.º 2 (febrero de 2002): 323–30. http://dx.doi.org/10.3171/jns.2002.96.2.0323.
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Object. The value of transcranial Doppler ultrasonography for the detection of middle cerebral artery (MCA) spasm has been asserted. None of the published studies, however, has adequately scrutinized the overall diagnostic accuracy of this procedure. There are only sporadic reports concerning the utility of transcranial color Doppler (TCCD) ultrasonography, although this method has been proved to be more precise. In this study the authors attempted to estimate the performance of TCCD ultrasonography in detecting MCA narrowing by using receiver operating characteristic (ROC) curve analysis, based on TCCD studies obtained in a relatively large, randomly selected population of patients. Methods. Transcranial color Doppler ultrasonography studies were obtained in 100 consecutive patients (54 men and 46 women ages 18–74 years, median age 50 years) routinely referred by neurosurgeons for intraarterial angiography. The M1 segment of the MCA was insonated using a 2.5-MHz probe via a temporal acoustic window, and angle-corrected flow velocities were obtained. Angiographically depicted vasospasm was graded as none, mild (≤ 25% vessel caliber reduction), and moderate to severe (> 25% vessel caliber reduction). The effectiveness of TCCD ultrasonography in diagnosing MCA spasm was evaluated by calculating the areas under the ROC curves (Az). Of the 200 MCAs examined, 173 were successfully visualized with the aid of TCCD ultrasonography. Mild vasospasm was angiographically diagnosed in 15 arteries and moderate-to-severe vasospasm in 28. The best-performing TCCD parameter for the detection of MCA narrowing was revealed to be peak systolic velocity. The Az value for moderate-to-severe vasospasm only was 0.93 and that for all vasospasms was 0.8. The best efficiency, that is, the optimal tradeoff between sensitivity and specificity in diagnosing vasospasms, was associated with a peak systolic velocity of 182 cm/second. Conclusions. The performance of TCCD ultrasonography in the diagnosis of advanced MCA narrowing is very good, and is acceptable for all vasospasms. The best-performing parameter was peak systolic velocity.
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Nieh, J. C. y J. Tautz. "Behaviour-locked signal analysis reveals weak 200–300 Hz comb vibrations during the honeybee waggle dance". Journal of Experimental Biology 203, n.º 10 (15 de mayo de 2000): 1573–79. http://dx.doi.org/10.1242/jeb.203.10.1573.
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Waggle-dancing honeybees produce vibratory movements that may facilitate communication by indicating the location of the waggle dancer. However, an important component of these vibrations has never been previously detected in the comb. We developed a method of fine-scale behavioural analysis that allowed us to analyze separately comb vibrations near a honeybee waggle dancer during the waggle and return phases of her dance. We simultaneously recorded honeybee waggle dances using digital video and laser-Doppler vibrometry, and performed a behaviour-locked Fast Fourier Transform analysis on the substratum vibrations. This analysis revealed significantly higher-amplitude 200–300 Hz vibrations during the waggle phase than during the return phase (P=0.012). We found no significant differences in the flanking frequency regions between 100–200 Hz (P=0.227) and 300–400 Hz (P=0.065). We recorded peak waggle phase vibrations from 206 to 292 Hz (244+/−28 Hz; mean +/− s. d., N=11). The maximum measured signal - noise level was +12.4 dB during the waggle phase (mean +5.8+/−2.7 dB). The maximum vibrational velocity, calculated from a filtered signal, was 128 microm s(−)(1) peak-to-peak, corresponding to a displacement of 0.09 microm peak-to-peak at 223 Hz. On average, we measured a vibrational velocity of 79+/−28 microm s(−)(1) peak-to-peak from filtered signals. These signal amplitudes overlap with the detection threshold of the honeybee subgenual organ.
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Li, Jie, Bingzhe Dai, Jiahao Zhou, Junchao Zhang, Qilin Zhang, Jing Yang, Yao Wang et al. "Preliminary Application of Long-Range Lightning Location Network with Equivalent Propagation Velocity in China". Remote Sensing 14, n.º 3 (25 de enero de 2022): 560. http://dx.doi.org/10.3390/rs14030560.
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The equivalent propagation method adopts a variable propagation velocity in lightning location, minimizing the location error caused by various factors in the long-range lightning location network. To verify the feasibility of this method, we establish a long-range lightning location network in China. A new method is used to extract the ground wave peak points of the lightning sferics and is combined with the equivalent propagation velocity method for lightning location. By comparing with the lightning data detected by the lightning locating system called advanced direction and time-of-arrival detecting (ADTD) that has been widely used for tens of years in China, the feasibility of this method is initially verified. Additionally, it is found that the relative detection efficiency of our long-range lightning location network can reach 53%, the average location error is 9.17 km, and the detection range can reach more than 3000 km. The equivalent propagation method can improve the average location accuracy by ~1.16 km, compared with the assumed light speed of lightning-radiated sferic from the lightning stroke point to the observation station. The 50th percentile of the equal propagation velocity is 0.998c, which may be used in the long-range lightning location networks.
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Angelaki, D. E. y B. J. Hess. "Three-dimensional organization of otolith-ocular reflexes in rhesus monkeys. II. Inertial detection of angular velocity". Journal of Neurophysiology 75, n.º 6 (1 de junio de 1996): 2425–40. http://dx.doi.org/10.1152/jn.1996.75.6.2425.
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1. The dynamic contribution of otolith signals to three-dimensional angular vestibuloocular reflex (VOR) was studied during off-vertical axis rotations in rhesus monkeys. In an attempt to separate response components to head velocity from those to head position relative to gravity during low-frequency sinusoidal oscillations, large oscillation amplitudes were chosen such that peak-to-peak head displacements exceeded 360 degrees. Because the waveforms of head position and velocity differed in shape and frequency content, the particular head position and angular velocity sensitivity of otolith-ocular responses could be independently assessed. 2. During both constant velocity rotation and low-frequency sinusoidal oscillations, the otolith system generated two different types of oculomotor responses: 1) modulation of three-dimensional eye position and/or eye velocity as a function of head position relative to gravity, as presented in the preceding paper, and 2) slow-phase eye velocity as a function of head angular velocity. These two types of otolith-ocular responses have been analyzed separately. In this paper we focus on the angular velocity responses of the otolith system. 3. During constant velocity off-vertical axis rotations, a steady-state nystagmus was elicited that was maintained throughout rotation. During low-frequency sinusoidal off-vertical axis oscillations, dynamic otolith stimulation resulted primarily in a reduction of phase leads that characterize low-frequency VOR during earth-vertical axis rotations. Both of these effects are the result of an internally generated head angular velocity signal of otolithic origin that is coupled through a low-pass filter to the VOR. No change in either VOR gain or phase was observed at stimulus frequencies larger than 0.1 Hz. 4. The dynamic otolith contribution to low-frequency angular VOR exhibited three-dimensional response characteristics with some quantitative differences in the different response components. For horizontal VOR, the amplitude of the steady-state slow-phase velocity during constant velocity rotation and the reduction of phase leads during sinusoidal oscillation were relatively independent of tilt angle (for angles larger than approximately 10 degrees). For vertical and torsional VOR, the amplitude of steady-state slow-phase eye velocity during constant velocity rotation increased, and the phase leads during sinusoidal oscillation decreased with increasing tilt angle. The largest steady-state response amplitudes and smallest phase leads were observed during vertical/torsional VOR about an earth-horizontal axis. 5. The dynamic range of otolith-borne head angular velocity information in the VOR was limited to velocities up to approximately 110 degrees/s. Higher head velocities resulted in saturation and a decrease in the amplitude of the steady-state response components during constant velocity rotation and in increased phase leads during sinusoidal oscillations. 6. The response characteristics of otolith-borne angular VORs were also studied in animals after selective semicircular canal inactivation. Otolith angular VORs exhibited clear low-pass filtered properties with a corner frequency of approximately 0.05-0.1 Hz. Vectorial summation of canal VOR alone (elicited during earth-vertical axis rotations) and otolith VOR alone (elicited during off-vertical axis oscillations after semicircular canal inactivation) could not predict VOR gain and phase during off-vertical axis rotations in intact animals. This suggests a more complex interaction of semicircular canal and otolith signals. 7. The results of this study show that the primate low-frequency enhancement of VOR dynamics during off-vertical axis rotation is independent of a simultaneous activation of the vertical and torsional “tilt” otolith-ocular reflexes that have been characterized in the preceding paper. (ABSTRACT TRUNCATED)
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Garcia, Julio, Kailey Beckie, Ali F. Hassanabad, Alireza Sojoudi y James A. White. "Aortic and mitral flow quantification using dynamic valve tracking and machine learning: Prospective study assessing static and dynamic plane repeatability, variability and agreement". JRSM Cardiovascular Disease 10 (enero de 2021): 204800402199990. http://dx.doi.org/10.1177/2048004021999900.
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Background Blood flow is a crucial measurement in the assessment of heart valve disease. Time-resolved flow using magnetic resonance imaging (4 D flow MRI) can provide a comprehensive assessment of heart valve hemodynamics but it relies in manual plane analysis. In this study, we aimed to demonstrate the feasibility of automate the detection and tracking of aortic and mitral valve planes to assess blood flow from 4 D flow MRI. Methods In this prospective study, a total of n = 106 subjects were enrolled: 19 patients with mitral disease, 65 aortic disease patients and 22 healthy controls. Machine learning was employed to detect aortic and mitral location and motion in a cine three-chamber plane and a perpendicular projection was co-registered to the 4 D flow MRI dataset to quantify flow volume, regurgitant fraction, and a peak velocity. Static and dynamic plane association and agreement were evaluated. Intra- and inter-observer, and scan-rescan reproducibility were also assessed. Results Aortic regurgitant fraction was elevated in aortic valve disease patients as compared with controls and mitral valve disease patients ( p < 0.05). Similarly, mitral regurgitant fraction was higher in mitral valve patients ( p < 0.05). Both aortic and mitral total flow were high in aortic patients. Static and dynamic were good (r > 0.6, p < 0.005) for aortic total flow and peak velocity, and mitral peak velocity and regurgitant fraction. All measurements showed good inter- and intra-observer, and scan-rescan reproducibility. Conclusion We demonstrated that aortic and mitral hemodynamics can efficiently be quantified from 4 D flow MRI using assisted valve detection with machine learning.
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Pan, Ya’ni, Zhili Jin, Pengfei Tong, Weiwei Xu y Wei Wang. "Edge Detection Method for Determining Boundary Layer Height Based on Doppler Lidar". Atmosphere 12, n.º 9 (26 de agosto de 2021): 1103. http://dx.doi.org/10.3390/atmos12091103.
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The top of the boundary layer, referred to as the planetary boundary layer height (BLH), is an important physical parameter in atmospheric numerical models, which has a critical role in atmospheric simulation, air pollution prevention, and climate prediction. The traditional methods for determining BLHs using Doppler lidar vertical velocity variance (σw2) can be classified into the variance and peak methods, which depend on atmospheric conditions due to their use of a single threshold, hence limiting their ability to estimate diurnal BLHs. Edge detection (ED) was later introduced in BLH estimation due to its ability to identify the 2D gradient of an image. A key step in ED is automatically identifying the edge of BLHs based on the peaks of the profile, hence avoiding the influence of extreme atmospheric conditions. Two cases in the diurnal cycle on 4 March 2019 and 8 July 2019 reveal that ED outperforms both the variance and peak methods in nighttime and extreme atmospheric conditions. The retrieved BLHs from 2018 to 2020 were compared with radiosonde (RS) measurements for the same time at the neutral, stable, and convective boundary layers. The correlation coefficient (R: 0.4 vs. 0.05, 0.14; 0.26 vs. −0.10, −0.16; 0.35 vs. 0.01, 0.16) and root mean square error (RMSE (km): 0.58 vs. 0.82, 0.90; 0.37 vs. 1.01, 0.50; 0.66 vs. 0.98, 0.82) obtained by the ED method were higher and lower than those obtained by the variance and peak methods, respectively. The mean absolute error (MAE) of the ED method under the NBL, SBL, and CBL conditions are lower than the variance and peak methods (MAE (km): 0.44, 0.14, 0.50 vs. 0.62, 0.34, 0.64; 0.59, 0.75, 0.74), respectively. The mean relative error (MRE) of the ED method is lower than the variance and peak methods under the NBL condition (MRE: −8.88% vs. −18.39%, 13.91%). Under the SBL, the MRE of the ED method is lower than the variance method and higher than the peak method (−38.64%, vs. −152.23%; 14.02%). Under the CBL, the MRE of the ED method is lower than the variance method and higher than the peak method (−15.07% vs. 2.24%; 5.64%). In addition, the comparison between ED and wavelet covariance transform (WCT) method and RS measurements showed that the ED method has a similar performance with the WCT method and is even better. In the long-term analysis, the hourly and monthly BLHs in the diurnal and annual cycles, respectively, as obtained by ED, were highly consistent with the RS measurements and obtained the lowest standard error. In the annual cycle, the retrieved BLHs in summer and autumn were higher than those retrieved in spring and winter.
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Leung, K. Y., C. P. Lee, M. H. Y. Tang, H. Y. Chan, E. S. K. Ma y V. Chan. "Detection of increased middle cerebral artery peak systolic velocity in fetuses affected by hemoglobin H Quong Sze disease". Ultrasound in Obstetrics and Gynecology 23, n.º 5 (mayo de 2004): 525–26. http://dx.doi.org/10.1002/uog.1051.
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Benedict, G. Fritz, Beverly J. Smith y J. D. P. Kenney. "CO in NGC 4314: The Detection of Inflow Along the Bar". International Astronomical Union Colloquium 157 (1996): 227–29. http://dx.doi.org/10.1017/s0252921100049794.
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AbstractWe present CO(1-0) interferometer data with × spatial resolution and 13 km s−1 velocity resolution acquired at the Owens Valley Radio Observatory. These data reveal a clumpy circumnuclear ring of gas. We also find a central peak of CO within 2″ of the optical center. Deviations from circular motion are seen where the dust lanes along the leading edge of the bar intersect the nuclear ring, consistent with gas inflow along the bar. Hα maps of this galaxy show bright HII regions near the ends of this inflow region, indicating triggering of star formation by the inflow.
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Pogson, Jacob M., Rachael L. Taylor, Andrew P. Bradshaw, Leigh McGarvie, Mario D’Souza, G. Michael Halmagyi y Miriam S. Welgampola. "The human vestibulo-ocular reflex and saccades: normal subjects and the effect of age". Journal of Neurophysiology 122, n.º 1 (1 de julio de 2019): 336–49. http://dx.doi.org/10.1152/jn.00847.2018.
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Here we characterize in 80 normal subjects (16–84 yr (means ± SD, 47 ± 19 yr) the vestibulo-ocular reflex (VOR) and saccades in response to three-dimensional head impulses with a monocular video head impulse test (vHIT) of the right eye. Impulses toward the right lateral, right anterior, and left posterior canals (means: 0.98, 0.91, 0.79) had slightly higher mean gains compared with their counterparts (0.95, 0.86, 0.76). In the older age group (>60 yr), gains of the left posterior canal dropped 0.09 and left anterior canals rose 0.09 resulting in symmetry. All canal gains reduced with increasing head velocity (0.02–0.13 per 100°/s). Comparison of lateral canal gains calculated using five published algorithms yielded lower values (~0.80) when a narrow detection window was used. Low-amplitude refixation saccades (amplitude: 1.11 ± 0.98°, peak velocity: 63.9 ± 34.0°/s at 262.0 ± 93.9 ms) were observed among all age groups (frequency: 40.2 ± 23.4%), increasing in amplitude, peak velocity, and frequency in older subjects. Impulses toward anterior canals showed the least frequent saccades and lateral and posterior canals were similar, but lateral canal impulses showed the smallest saccades and the posterior canal showed the largest saccades. Saccade peak-velocity approximate amplitude “main sequence” slope was steeper for the horizontal canals compared with the vertical planes (60 vs. <40°/s per 1°). In summary, we found small but significant asymmetries in monocular vHIT gain that changed with age. Healthy subjects commonly have minuscule refixation saccades that are moderately to strongly correlated with vHIT gain. NEW & NOTEWORTHY Gaze fixation is normally stabilized during rapid “head-impulse” movements by the bisynaptic vestibulo-ocular reflex (VOR), but earlier studies of normal subjects also report small amplitude saccades. We found that with increased age of the subject the vertical VOR became more variable, while in all semicircular canal directions the saccade frequency, amplitude, and peak velocity increased. We also found that the VOR gain algorithm significantly influences values.
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Liu, Bo, Li Gong y Quan Jie Song. "Structural Detection and Safety Ensuring Methods of Impervious Wall during Nuclear Power Plant Construction". Applied Mechanics and Materials 256-259 (diciembre de 2012): 1125–30. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.1125.
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Combined with the dynamic compaction example of a nuclear power plant, a fully field tests was conducted to get the permeability and integrality of the impervious wall in real time. The dynamic compaction vibration impact on impervious wall was researched based on the test results. The relationships between damage characteristic and peak particle velocity of impervious wall are suggested also. The safety control standards which used vibration safety threshold to control the potential damage for impervious wall under long-term dynamic compaction were presented. When the PPV of impervious wall is not exceeding the safety threshold, the impervious wall will in its secured state. According to the damage detection method and the presented safety threshold of vibration velocity, the protected structure can be simply and protected during dynamic compaction. The research methods reflects the damage of protected structure directly, and more accurate and safety than traditional methods.
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Saberi, M., W. H. T. Vlemmings, E. De Beck, R. Montez y S. Ramstedt. "Detection of CI line emission towards the oxygen-rich AGB star omi Ceti". Astronomy & Astrophysics 612 (abril de 2018): L11. http://dx.doi.org/10.1051/0004-6361/201833080.
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We present the detection of neutral atomic carbon CI(3P1–3P0) line emission towards omi Cet. This is the first time that CI is detected in the envelope around an oxygen-rich M-type asymptotic giant branch (AGB) star. We also confirm the previously tentative CI detection around V Hya, a carbon-rich AGB star. As one of the main photodissociation products of parent species in the circumstellar envelope (CSE) around evolved stars, CI can be used to trace sources of ultraviolet (UV) radiation in CSEs. The observed flux density towards omi Cet can be reproduced by a shell with a peak atomic fractional abundance of 2.4 × 10−5 predicted based on a simple chemical model where CO is dissociated by the interstellar radiation field. However, the CI emission is shifted by ~4 km s−1 from the stellar velocity. Based on this velocity shift, we suggest that the detected CI emission towards omi Cet potentially arises from a compact region near its hot binary companion. The velocity shift could, therefore, be the result of the orbital velocity of the binary companion around omi Cet. In this case, the CI column density is estimated to be 1.1 × 1019 cm−2. This would imply that strong UV radiation from the companion and/or accretion of matter between two stars is most likely the origin of the CI enhancement. However, this hypothesis can be confirmed by high-angular resolution observations.
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Hossain, Md Iftekhar, Ehsan Alam Chowdhury, AA Mamun, A. Salam, Tanvir Noor Baig y K. Siddique-e. Rabbani. "Use of Distribution of F-Latency (DFL) in the Detection of Cervical Spondylotic Neuropathy". Bangladesh Journal of Medical Physics 4, n.º 1 (19 de abril de 2013): 37–42. http://dx.doi.org/10.3329/bjmp.v4i1.14676.
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Distribution of F-latencies (DFL) is a new nerve conduction parameter introduced by our laboratory to give a distribution of the conduction velocity (DCV) of motor nerve fibres in a peripheral nerve trunk simply as its mirror image. Earlier work revealed an association between Cervical Spondylotic (CS) neuropathy and DFL patterns obtained from the thenar muscle at the base of the thumb by artificially stimulating the median nerve. DFL froom normal subjects had a single peaked pattern, while that from subjects with CS had double or triple peaks, or a broad peak. The broad peak was suggested to be an indicator of early CS, even when the symptoms are not fully apparent. This led to some hypotheses based on physics, physiology and statistics, in order to explain such patterns. In order to verify these hypotheses, experiments need to be carried out carefully, and the present work is a step towards that goal. In this work DFL of the median nerve was obtained from 15 subjects, 6 normal, and 9 with diagnosed cervical spondylosis. The latter were subjected to further X-ray and MRI investigations, performed blindly at regular clinics. All of the 9 subjects were identified with either compression of nerve roots (radiculopathy), or spinal cord compression due to the bulging of the inter-vertebral discs (myelopathy). This shows with confidence that double or triple peaks of DFL indeed relates to CS, and broad peaks indicate their early stage. The same concept may be extended to other peripheral nerves, both in the hands and legs. Thus DFL may become an important screening test for neuropathy, as a first choice, offering a low cost and widely available test compared to the only other alternative, MRI, for such diagnosis. DOI: http://dx.doi.org/10.3329/bjmp.v4i1.14676 Bangladesh Journal of Medical Physics Vol.4 No.1 2011 37-42
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Song, Jaewoo, Eunyoung Lee, Yula Jeon, Ji Eun Jang, Yundeok Kim, June-Won Cheong y Yoo Hong Min. "Improved Sensitivity and Discriminative Power of Factor FVIII Assay By Applying Turbidimetric Clotting Curve Analysis". Blood 124, n.º 21 (6 de diciembre de 2014): 2853. http://dx.doi.org/10.1182/blood.v124.21.2853.2853.
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Abstract Background: The need for sensitive detection of coagulation factor between the levels of 0.0 and1.0% is now growing continuously. The most popular method of measuring factor VIII (FVIII) activity is one stage clotting time (activated partial thromboplastin time, APTT)-based assay. From the first and the second derivatives of the original turbidimetric curve, the velocity and acceleration of clot formation can be followed and parameters like maximum velocity (peak1) and acceleration (peak2) of clot formation can also be derived. We examined the limit of detection of FVIII activities measured based on clotting time, peak1 and peak2, following the recommendations from Clinical and Laboratory Standards Institute guideline. Method: We performed APTT with sample/reagent volume and incubation time modified to be identical to those adopted for factor assay on factor deficient plasma as blank and plasmas prepared to have variable FVIII activities from 0.1 to 1.6%. Peak1 and Peak2 were also measured to determine the limit of blank (LoB) and limit of detection (LoD) corresponding to each parameter. Also, by modifying the method of LoB and LoD determination, we determined lower limit of 1.0% (lower Lo1) corresponding to each parameter. Results: The mean clotting time of blank sample (FVIII 0.0%) was 131.4 ± 1.90 seconds (mean ± SD). Thus, 95% of clotting times measured from a blank sample (FVIII 0.0%) are longer than 128.3 seconds, which was determined to be the LoB for clotting time. The pooled standard deviation (SD) of clotting times measured from low FVIII samples was 2.29 seconds and 124.49 seconds which was the theoretically minimum value that was statistically different from LoB was set as the clotting time corresponding to LoD of FVIII. The LoD clotting time was between the clotting times of FVIII 0.2% and FVIII 0.4% sample and 0.4% was safely determined to be LoD of FVIII. This implied that plasma sample with at least 0.4% FVIII level was guaranteed to be measured higher than blank (FVIII 0.0%) sample. The mean peak1 height for blank sample was 21.4 ± 0.68 and LoB peak height was determined to be 22.53. The pooled SD for peak1 height was 0.68 and peak1 height of LoD was calculated to be 23.63. Because the mean peak1 height for 0.2% sample was 24.27, the LoD FVIII activity could be safely determined to be 0.2%. Thus, by applying peak1 as primary measure to estimate FVIII activity, the sensitivity of FVIII assay was increased with lower LoD of 0.2% compared with clotting time based assay. For peak2 height, LoB and LoD peak2 height were 14.86 and 18.59 respectively and The LoD could be set at FVIII 0.4%. Next, we determined lower Lo1, which meant FVIII level that was guaranteed to be measured significantly lower than 1.0% sample. For clotting time, lower Lo1 was FVIII 0.2% and for peak1 and 2 FVIII, was 0.4%. These results implied that by conventional clotting time based FVIII assay FVIII activity between 0.0 and 1.0% could not be measured credibly. FVIII should be at least 0.4% to be ever detected but ironically FVIII should be less than 0.2% to be assuredly measured lower than 1.0%. However, with peak1 there was an interval of FVIII value that could be assured to be measured higher than 0.0% but lower than 1.0%. Conclusion: We concluded that the maximum clotting velocity derived from turbidimetric curve analysis can be applied to measure FVIII activity between 0.0 and 1.0% credibly. Disclosures No relevant conflicts of interest to declare.
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Fabrizio, Aghini-Lombardi, Di Bello Vitantonio, Talini Enrica, Di Cori Andrea, Monzani Fabio, Antonangeli Lucia, Palagi Caterina et al. "Early textural and functional alterations of left ventricular myocardium in mild hypothyroidism". European Journal of Endocrinology 155, n.º 1 (julio de 2006): 3–9. http://dx.doi.org/10.1530/eje.1.02174.
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The aim of the present study was to evaluate cardiac function and texture in patients with subclinical hypothyroidism (sHT) both by conventional and new ultrasonic intramyocardial tissue techniques. sHT was characterized by normal serum free tetraiodotironine and free triiodotironine levels and slightly increased serum TSH level. Twenty-four patients affected by sHT and 24 sex- and age-matched healthy volunteers were studied. All subjects were submitted to conventional two-dimensional (2D)-color Doppler echocardiography, pulsed wave tissue Doppler imaging (PWTDI) for the analysis of the diastolic function, color Doppler myocardial imaging (CDMI) for the analysis of regional strain and strain-rate and integrated backscatter (IBS) for the evaluation of intrinsic contractility and tissue characterization. The results of the present study were: (a) the detection in sHT subjects of a lower cyclic variation index (CVI) indicating an altered myocardial intrinsic contractility; (b) a higher ultrasonic myocardial reflectivity indicating an altered myocardial texture; (c) the detection of lower systolic strain and strain-rate indicating an alteration of myocardial regional deformability; (d) an initial impairment of left ventricular diastolic function indicated by a decrease of peak E mitral flow velocity and an increase of peak A mitral flow velocity. All parameters studied with conventional 2D-echo in sHT patients were comparable with controls, except for a mild alteration in diastolic function. A significant correlation among systo-diastolic modifications detected by CDMI and IBS and serum TSH levels were found. The CVI at septum, the PWDTI S-peak wave and the systolic strain at septum were inversely related to the serum TSH levels. In conclusion, the new intramyocardial ultrasonic techniques confirm and extend the previous knowledge on the effect of the sHT on the heart, allowing the detection of early ultrastructural and regional functional systolic and diastolic abnormalities.
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Ascenzi, Stefano, Michael W. Coughlin, Tim Dietrich, Ryan J. Foley, Enrico Ramirez-Ruiz, Silvia Piranomonte, Brenna Mockler et al. "A luminosity distribution for kilonovae based on short gamma-ray burst afterglows". Monthly Notices of the Royal Astronomical Society 486, n.º 1 (28 de marzo de 2019): 672–90. http://dx.doi.org/10.1093/mnras/stz891.
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Abstract The combined detection of a gravitational-wave signal, kilonova, and short gamma-ray burst (sGRB) from GW170817 marked a scientific breakthrough in the field of multimessenger astronomy. But even before GW170817, there have been a number of sGRBs with possible associated kilonova detections. In this work, we re-examine these ‘historical’ sGRB afterglows with a combination of state-of-the-art afterglow and kilonova models. This allows us to include optical/near-infrared synchrotron emission produced by the sGRB as well as ultraviolet/optical/near-infrared emission powered by the radioactive decay of r-process elements (i.e. the kilonova). Fitting the light curves, we derive the velocity and the mass distribution as well as the composition of the ejected material. The posteriors on kilonova parameters obtained from the fit were turned into distributions for the peak magnitude of the kilonova emission in different bands and the time at which this peak occurs. From the sGRB with an associated kilonova, we found that the peak magnitude in H bands falls in the range [−16.2, −13.1] ($95{{\ \rm per\ cent}}$ of confidence) and occurs within $0.8\!-\!3.6\, \rm d$ after the sGRB prompt emission. In g band instead we obtain a peak magnitude in range [−16.8, −12.3] occurring within the first 18 h after the sGRB prompt. From the luminosity distributions of GW170817/AT2017gfo, kilonova candidates GRB130603B, GRB050709, and GRB060614 (with the possible inclusion of GRB150101B, GRB050724A, GRB061201, GRB080905A, GRB150424A, and GRB160821B) and the upper limits from all the other sGRBs not associated with any kilonova detection we obtain for the first time a kilonova luminosity distribution in different bands.
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Rashid, Khandaker Harun or, Dipal Krishna Adhikary, Sajal Krishna Banerjee, Tanjima Parvin, Abu Baqar Md Jamil, Md Tufazzal Hossain, Mrinal Kanti Das, ATM Iqbal Hasan y Md Ashraf Uddin Sultan. "Comparison Between Isovolumic Acceleration and Conventional Echocardiograhic Parameters in Detecting Early Right Ventricular Systolic Dysfunction in Patients with Mitral Stenosis". University Heart Journal 18, n.º 2 (8 de noviembre de 2022): 80–86. http://dx.doi.org/10.3329/uhj.v18i2.62676.
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Aim: The aim of the study was to determine if the tissue Doppler imaging (TDI)-derived myocardial acceleration during isovolumic contraction (IVA) of tricuspid lateral annulus could be used in early detection of RV systolic dysfunction in patients with mitral stenosis (MS), before the clinical signs of systemic venous congestion occur and to compare between IVA and conventional echocardiographic parameters in detecting early RV systolic dysfunction in patients with MS .
Methods: Ninety-six patients with severe rheumatic MS without relevant regurgitation were enrolled in the study. Conventional echocardiographic parameters (mitral valve area, transmitral diastolic gradients, pulmonary artery pressure, RV fractional area change, pulmonary flow acceleration time, tricuspid annular plane systolic excursion) and TDI-derived systolic velocities of tricuspid annulus (isovolumic myocardial acceleration: IVA, peak myocardial velocity during isovolumic contraction: IVV, peak systolic velocity during ejection period: Sa and RV MPI) were recorded from all patients.
Results: TDI-derived IVA, IVV, Sa were significantly decreased in patients with MS and RV MPI is increased in patients with MS. IVA was the only parameter which had a significant negative correlation with the traditional echocardiographic parameters and RV Tei index in patients with MS.
Conclusion: TDI-derived right ventricular IVA may be used as an adjunctive, reliable, noninvasive parameter for the early detection of right ventricular systolic dysfunction in patients with MS but without signs of systemic venous congestion. RV IVA negatively correlate with RV MPI, positively correlate with IVV and Sa. RV IVA shows positive correlation with RVFAC and negative correlation with PAP, LA size. IVA shows no correlation with TAPSE.
University Heart Journal 2022; 18(2): 80-86
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Wood, P. R., M. S. Bessell y J. B. Whiteoak. "Detection of the first extra-galactic OH/IR star". Symposium - International Astronomical Union 122 (1987): 241. http://dx.doi.org/10.1017/s0074180900156505.
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A search has been made for 1612 MHz OH maser emission from OH/IR stars in the Magellanic Clouds. Candidate objects were selected mainly on the basis of their 25μm flux densities and the 25 to 12μm flux ratio as given in the IRAS point source catalog; two known long-period variables and two HII regions (30 Doradus and N159) were also examined. One OH source (IRAS 04553-6825) was detected, this being the first OH/IR star found in the Magellanic Clouds. Upper limits were placed on the flux for 17 other sources. The expansion velocity of the circumstellar material surrounding IRAS 04553-6825, as indicated by the OH peak separation of 11 km s−1, is surprisingly small compared to Galactic sources of similar bolometric and OH luminosity. The OH intensity of IRAS 04553-6825, and the upper flux limits placed on many of the other objects examined, indicate that Magellanic Cloud OH/IR stars do not emit OH as strongly as their Galactic counterparts of similar 25μm/12μm flux ratio. Both the low expansion velocity of IRAS 04553-6825 and the low OH intensity of the Magellanic Cloud infrared sources may be explained by the low metal abundance in the Clouds.
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Loranger, Michel, Julien Treboz, Jean-Alexandre Boucher, François Nougarou, Claude Dugas y Martin Descarreaux. "Correlation of expertise with error detection skills of force application during spinal manipulation learning*". Journal of Chiropractic Education 30, n.º 1 (1 de marzo de 2016): 1–6. http://dx.doi.org/10.7899/jce-15-4.
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Objective: Most studies on spinal manipulation learning demonstrate the relevance of including motor learning strategies in chiropractic curricula. Two outcomes of practice are the production of movement in an efficient manner and the improved capability of learners to evaluate their own motor performance. The goals of this study were to evaluate if expertise is associated with increased spinal manipulation proficiency and if error detection skills of force application during a high-velocity low-amplitude spinal manipulation are related to expertise. Methods: Three groups of students and 1 group of expert chiropractors completed 10 thoracic spine manipulations on an instrumented device with the specific goal of reaching a maximum peak force of 300 N after a brief period of practice. After each trial, participants were asked to give an estimate of their maximal peak force. Force-time profiles were analyzed to determine the biomechanical parameters of each participant and the participant's capacity to estimate his or her own performance. Results: Significant between-group differences were found for each biomechanical parameter. No significant difference was found between groups for the error detection variables (p > .05). The lack of significant effects related to the error detection capabilities with expertise could be related to the specificity of the task and how the training process was structured. Conclusion: This study confirms that improvements in biomechanical parameters of spinal manipulation are related to expertise. Feedback based on error detection could be implemented in chiropractic curricula to improve trainee abilities in detecting motor execution errors.
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Nij Bijvank, J. A., L. J. van Rijn, L. J. Balk, H. S. Tan, B. M. J. Uitdehaag y A. Petzold. "Diagnosing and quantifying a common deficit in multiple sclerosis". Neurology 92, n.º 20 (19 de abril de 2019): e2299-e2308. http://dx.doi.org/10.1212/wnl.0000000000007499.
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ObjectiveWe present an objective and quantitative approach for diagnosing internuclear ophthalmoplegia (INO) in multiple sclerosis (MS).MethodsA validated standardized infrared oculography protocol (DEMoNS [Demonstrate Eye Movement Networks with Saccades]) was used for quantifying prosaccades in patients with MS and healthy controls (HCs). The versional dysconjugacy index (VDI) was calculated, which describes the ratio between the abducting and adducting eye. The VDI was determined for peak velocity, peak acceleration, peak velocity divided by amplitude, and area under the curve (AUC) of the saccadic trajectory. We calculated the diagnostic accuracy for the several VDI parameters by a receiver operating characteristic analysis comparing HCs and patients with MS. The National Eye Institute Visual Function Questionnaire–25 was used to investigate vision-related quality of life of MS patients with INO.ResultsTwo hundred ten patients with MS and 58 HCs were included. The highest diagnostic accuracy was achieved by the VDI AUC of 15° horizontal prosaccades. Based on a combined VDI AUC and peak velocity divided by amplitude detection, the prevalence of an INO in MS calculated to 34%. In the INO group, 35.2% of the patients with MS reported any complaints of double vision, compared to 18.4% in the non-INO group (p = 0.010). MS patients with an INO had a lower overall vision-related quality of life (median 89.9, interquartile range 12.8) compared to patients without an INO (median 91.8, interquartile range 9.3, p = 0.011).ConclusionsThis study provides an accurate quantitative and clinically relevant definition of an INO in MS. This infrared oculography-based INO standard will require prospective validation. The high prevalence of INO in MS provides an anatomically well described and accurately quantifiable model for treatment trials in MS.
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Michalaki, Vasiliki, George Koutroulis, Ioannis Kontis, Nikolaos Dafnios, Dina Tiniakos y Christos Papadimitriou. "Use of strain rate imaging for early detection of epirubicin-induced cardiotoxicity in patients with breast cancer." Journal of Clinical Oncology 39, n.º 15_suppl (20 de mayo de 2021): e12531-e12531. http://dx.doi.org/10.1200/jco.2021.39.15_suppl.e12531.
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e12531 Background: Although epirubicin has improved outcome in breast cancer (BC) patients, its application is limited by its cardiotoxicity . Assessment of left ventricular (LV) ejection fraction (EF) is performed to demonstrate cardiac dysfunction. Changes in cardiac function induced by this therapy, however, are difficult to quantitate by conventional echocacardiography. Tissue Doppler myocardial imaging (TDI) derived wall motion velocity, and strain rate (SR) have been shown to sensitively quantify abnormalities in cardiac function. The aim of this study was to determine if sensitive indices of LV dysfunction, would be useful for addressing the early detection of cardiotoxic side effects of epirubicin. Methods: BC patients (N = 45 median age 60.2years) without cardiovascular risk factors were prospectively included. All patients received epirubicin. Twenty patients received further trastuzumab. Conventional and TDI echocardiography were obtained at baseline , every 2cycles of treatment and 3 months after chemotherapy. Segmental peak systolic longitudinal and radial velocity, SR and strain, were measured. Results: at baseline, median LV-EF was > 55 %. There was no overall change in LV dimensions, EF and peak systolic velocity. In contrast, a significant reduction in longitudinal and radial SR and strain was found after 3 cycles (longitudinal strain -10.2% +/- 1.3 % vs baseline 22 +/- 4.1 %, P = .001; radial strain 26.1% +/-4,2% vs baseline 47.3% +/- 9.2 %, P < .001). Changes in radial strain appeared earlier and were more pronounced than longitudinal strain. Conclusions: In this study we confirm the clinical use of TDI parameters for early detection of epirubicin mediated cardiac dysfunction. TDI detected subtle changes of LV function after 3 cycles of therapy. Use of Strain Rate Imaging detects subclinical LV dysfunction and can predict further changes in EF ,therefore can be used to monitor epirubicin-induced cardiotoxicity.
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Ryzhyk, V. M. y I. D. Stasiv. "THE ROLE OF DOPPLER REGIMES IN THE DETECTION OF VOLUME OVARIAN FORMATIONS". PRECARPATHIAN BULLETIN OF THE SHEVCHENKO SCIENTIFIC SOCIETY Pulse, n.º 16-17-(61-62) (10 de agosto de 2022): 57–64. http://dx.doi.org/10.21802/2304-7437-2021-2022-16-17(61-62)-57-64.
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In order to increase the diagnostic value of ultrasound diagnostics, qualitative and quantitative Doppler indicators in the detection of bulky ovarian tumors were determined. A comprehensive examination of 149 patients with additional ovarian tumors, which consisted of three groups of patients. The control group included 30 women who did not have large ovarian tumors. Detailed qualitative assessment of blood flow loci was determined using energy Doppler, and quantitative – pulse. The main parameters that were evaluated were maximum blood flow velocity (Vmax), resistance index (IR), pulsation index (PI).Studies have shown that color Doppler showed neovascularity in 46 (95.8%) malignant tumors in contrast to only 35 (68.6%) benign tumors. Malignant tumors are characterized by a change in vascular velocity with an increase in peak systolic velocity and a decrease in the resistance index. Vmax and PI values increase slightly in tumor-like and benign tumors, but in malignant tumors they increase almost twice as much as in the control group (p <0.05), and RI on the contrary - halves in malignant pathology (p <0.05). In 33 (68.8%) cases of ovarian malignancies, the RI was <0.5 and none of the benign tumors had an RI <0.4. Most benign tumors (82.4%) had an RI> 0.6 (p <0.0001).The results of research show that Doppler imaging is an indispensable component of ultrasound in the differential diagnosis of bulky ovarian tumors, as neoangiogenesis has its own characteristics that can be effectively detected using Doppler modes.
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May, Ryan M., Michael I. Biggerstaff y Ming Xue. "A Doppler Radar Emulator with an Application to the Detectability of Tornadic Signatures". Journal of Atmospheric and Oceanic Technology 24, n.º 12 (1 de diciembre de 2007): 1973–96. http://dx.doi.org/10.1175/2007jtecha882.1.
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Abstract A Doppler radar emulator was developed to simulate the expected mean returns from scanning radar, including pulse-to-pulse variability associated with changes in viewing angle and atmospheric structure. Based on the user’s configuration, the emulator samples the numerical simulation output to produce simulated returned power, equivalent radar reflectivity, Doppler velocity, and Doppler spectrum width. The emulator is used to evaluate the impact of azimuthal over- and undersampling, gate spacing, velocity and range aliasing, antenna beamwidth and sidelobes, nonstandard (anomalous) pulse propagation, and wavelength-dependent Rayleigh attenuation on features of interest. As an example, the emulator is used to evaluate the detection of the circulation associated with a tornado simulated within a supercell thunderstorm by the Advanced Regional Prediction System (ARPS). Several metrics for tornado intensity are examined, including peak Doppler velocity and axisymmetric vorticity, to determine the degradation of the tornadic signature as a function of range and azimuthal sampling intervals. For the case of a 2° half-power beamwidth radar, like those deployed in the first integrated project of the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA), the detection of the cyclonic shear associated with this simulated tornado will be difficult beyond the 10-km range, if standard metrics such as azimuthal gate-to-gate shear from a single radar are used for detection.
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Okada, Yoko, Ronan Higgins, Volker Ossenkopf-Okada, Cristian Guevara, Jürgen Stutzki y Marc Mertens. "First detection of [13C II] in the Large Magellanic Cloud". Astronomy & Astrophysics 631 (noviembre de 2019): L12. http://dx.doi.org/10.1051/0004-6361/201936685.
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Context. [13C II] observations in several Galactic sources show that the fine-structure [12C II] emission is often optically thick (the optical depths around 1 to a few). Aims. Our goal was to test whether this also affects the [12C II] emission from nearby galaxies like the Large Magellanic Cloud (LMC). Methods. We observed three star-forming regions in the LMC with upGREAT on board SOFIA at the frequency of the [C II] line. The 4 GHz bandwidth covers all three hyperfine lines of [13C II] simultaneously. For the analysis, we combined the [13C II] F = 1−0 and F = 1−1 hyperfine components as they do not overlap with the [12C II] line in velocity. Results. Three positions in N159 and N160 show an enhancement of [13C II] compared to the abundance-ratio-scaled [12C II] profile. This is likely due to the [12C II] line being optically thick, supported by the fact that the [13C II] line profile is narrower than [12C II], the enhancement varies with velocity, and the peak velocity of [13C II] matches the [O I] 63 μm self-absorption. The [12C II] line profile is broader than expected from a simple optical depth broadening of the [13C II] line, supporting the scenario of several PDR components in one beam having varying [12C II] optical depths. The derived [12C II] optical depth at three positions (beam size of 14″, corresponding to 3.4 pc) is 1−3, which is similar to values observed in several Galactic sources shown in previous studies. If this also applies to distant galaxies, the [C II] intensity will be underestimated by a factor of approximately 2.
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Radu, Letitia Elena, Ioana Ghiorghiu, Alina Oprescu, Dan Dorobantu, Constantin Arion y Anca Colita. "Cardiotoxicity evaluation in pediatric patients with acute lymphoblastic leukemia – results of prospective study". Medical Ultrasonography 21, n.º 4 (24 de noviembre de 2019): 449. http://dx.doi.org/10.11152/mu-2012.
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Aim: The chemotherapy protocol for acute lymphoblastic leukemia (ALL) uses low doses of anthracyclines (AC), generally associated with subclinical cardiotoxicity. The aim of our study was to evaluate the serum biomarkers and echocardiography parameters in children with ALL treated with AC in order to determine the most useful element for early detection of cardiotoxicity.Material and methods: In this prospective study, troponin I (TnI) and heart-type fatty acid binding protein (HFABP) were assessed five times during the first year after the onset of ALL. Serial Tissue Doppler Imaging and conventional cardiac echography were performed by two pediatric cardiologists (intraclass correlation coefficient over 0.85 for all measurements) in three periods during the study protocol.Results: We evaluated 48 children with ALL. TnI increased during therapy, without returning to baseline values one year after diagnosis. HFABP did not show significant changes during the study protocol. Left ventricle outflow tract time-velocity integral and peak systolic septal mitral annulus velocity decreased during chemotherapy and returned to baseline levels at one year after diagnosis, while peak systolic tricuspid annulus velocity and excursion, maintained a descending tendency. Early filling transmitral flow velocity and E/A ratio were also transiently influenced by chemotherapy.Conclusions: The study showed signs of transient cardiotoxicity in the left ventricle and diastolic parameters after chemotherapy, compared to right ventricle parameters which maintained low values even one year after diagnosis. TnI proved to be directly proportional to chemotherapy doses but HFABP was not useful in this setting
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Lee, Seunghee, Bummo Koo, Sumin Yang, Jongman Kim, Yejin Nam y Youngho Kim. "Fall-from-Height Detection Using Deep Learning Based on IMU Sensor Data for Accident Prevention at Construction Sites". Sensors 22, n.º 16 (16 de agosto de 2022): 6107. http://dx.doi.org/10.3390/s22166107.
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Workers at construction sites are prone to fall-from-height (FFH) accidents. The severity of injury can be represented by the acceleration peak value. In the study, a risk prediction against FFH was made using IMU sensor data for accident prevention at construction sites. Fifteen general working movements (NF: non-fall), five low-hazard-fall movements, (LF), and five high-hazard-FFH movements (HF) were performed by twenty male subjects and a dummy. An IMU sensor was attached to the T7 position of the subject to measure the three-axis acceleration and angular velocity. The peak acceleration value, calculated from the IMU data, was 4 g or less in general work movements and 9 g or more in FFHs. Regression analysis was performed by applying various deep learning models, including 1D-CNN, 2D-CNN, LSTM, and Conv-LSTM, to the risk prediction, and then comparing them in terms of their mean absolute error (MAE) and mean squared error (MSE). The FFH risk level was estimated based on the predicted peak acceleration. The Conv-LSTM model trained by MAE showed the smallest error (MAE: 1.36 g), and the classification with the predicted peak acceleration showed the best accuracy (97.6%). This study successfully predicted the FFH risk levels and could be helpful to reduce fatal injuries at construction sites.
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González Lobos, Valentina y Amelia M. Stutz. "Gas velocity structure of the Orion A integral-shaped filament". Monthly Notices of the Royal Astronomical Society 489, n.º 4 (10 de septiembre de 2019): 4771–82. http://dx.doi.org/10.1093/mnras/stz2512.
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ABSTRACT We present analysis of the gas kinematics of the integral-shaped filament (ISF) in Orion A using four different molecular lines, 12CO (1−0), 13CO (1−0), NH3 (1,1), and N2H+ (1−0). We describe our method to visualize the position–velocity (PV) structure using the intensity-weighted line velocity centroid, which enables us to identify structures that were previously muddled or invisible. We observe a north-to-south velocity gradient in all tracers that terminates in a velocity peak near the centre of the Orion Nebula Cluster (ONC), consistent with the previously reported ‘wave-like’ properties of the ISF. We extract the velocity dispersion profiles and compare the non-thermal line widths to the gas gravitational potential. We find supersonic Mach number profiles, yet the line widths are consistent with the gas being deeply gravitationally bound. We report the presence of two 12CO velocity components along the northern half of the ISF; if interpreted as circular rotation, the angular velocity is $\omega =1.4\, {\rm Myr}^{-1}$. On small scales we report the detection of N2H+ and NH3 ‘twisting and turning’ structures, with short associated time-scales that give the impression of a torsional wave. Neither the nature of these structures nor their relation to the larger scale wave is presently understood.
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Reynolds, R. J., S. L. Tufte, L. M. Haffner, K. Jaehnig y J. W. Percival. "The Wisconsin Hα Mapper (WHAM): A Brief Review of Performance Characteristics and Early Scientific Results". Publications of the Astronomical Society of Australia 15, n.º 1 (1998): 14–18. http://dx.doi.org/10.1071/as98014.
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Abstract. The Wisconsin Hα Mapper (WHAM) is a recently completed facility for the detection and study of faint optical emission lines from diffuse ionised gas in the disk and halo of the Galaxy. WHAM consists of a 15 cm diameter Fabry–Perot spectrometer coupled to a 0·6 m ‘telescope’, which provide a 1° diameter beam on the sky and produce a 12 km s−1 resolution spectrum within a 200 km s−1 spectral window. This facility is now located at Kitt Peak in Arizona and operated remotely from Madison, Wisconsin, 2400 km distant. Early results include a velocity-resolved Hα map of a 70° × 100° region of the sky near the Galactic anticentre, the first detections of Hα emission from the M I and A high velocity clouds, and the first detections of [O I] λ6300 and other faint ‘diagnostic’ lines from the warm ionised medium. Through the summer of 1998, WHAM will be devoted almost exclusively to a survey of the northern sky, which will provide maps of the distribution and kinematics of the diffuse HII through the optical Hα line in a manner that is analogous to earlier sky surveys of the HI made through the 21 cm line.
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Draudvilienė, Lina, Asta Meškuotienė, Renaldas Raišutis, Olgirdas Tumšys y Lina Surgautė. "Accuracy Assessment of the 2D-FFT Method Based on Peak Detection of the Spectrum Magnitude at the Particular Frequencies Using the Lamb Wave Signals". Sensors 22, n.º 18 (7 de septiembre de 2022): 6750. http://dx.doi.org/10.3390/s22186750.
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The 2D-FFT is described as a traditional method for signal processing and analysis. Due to the possibility to determine the time and frequency (t,f) domains, such a method has a wide application in various industrial fields. Using that method, the obtained results are presented in images only; thus, for the extraction of quantitative values of phase velocities, additional algorithms should be used. In this work, the 2D-FFT method is presented, which is based on peak detection of the spectrum magnitude at particular frequencies for obtaining the quantitative expressions. The radiofrequency signals of ULWs (ultrasonic Lamb waves) were used for the accuracy evaluation of the method. An uncertainty evaluation was conducted to guarantee the metrological traceability of measurement results and ensure that they are accurate and reliable. Mathematical and experimental verifications were conducted by using signals of Lamb waves propagating in the aluminum plate. The obtained mean relative error of 0.12% for the A0 mode (160 kHz) and 0.05% for the S0 mode (700 kHz) during the mathematical verification indicated that the proposed method is particularly suitable for evaluating the phase-velocity dispersion in clearly expressed dispersion zones. The uncertainty analysis showed that the plate thickness, the mathematical modeling, and the step of the scanner have a significant impact on the estimated uncertainty of the phase velocity for the A0 mode. Those components of uncertainty prevail and make about ~92% of the total standard uncertainty in a clearly expressed dispersion range. The S0 mode analysis in the non-dispersion zone indicates that the repeatability of velocity variations, fluctuations of the frequency of Lamb waves, and the scanning step of the scanner influence significantly the combined uncertainty and represent 98% of the total uncertainty.
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Rocha, Helena, Ugo Lafont y João P. Nunes. "Optimisation of Through-Thickness Embedding Location of Fibre Bragg Grating Sensor in CFRP for Impact Damage Detection". Polymers 13, n.º 18 (12 de septiembre de 2021): 3078. http://dx.doi.org/10.3390/polym13183078.
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Aerospace composites are susceptible to barely visible impact damage (BVID) produced by low-velocity-impact (LVI) events. Fibre Bragg grating (FBG) sensors can detect BVID, but often FBG sensors are embedded in the mid-plan, where residual strains produced by impact damage are lower, leading to an undervaluation of the damage severity. This study compares the residual strains produced by LVI events measured by FBG embedded at the mid-plan and other through-thickness locations of carbon fibre reinforced polymer (CFRP) composites. The instrumented laminates were subjected to multiple low-velocity impacts while the FBG signals were acquired. The FBG sensor measurements allowed not only for the residual strain after damage to be measured, but also for a strain peak at the time of impact to be detected, which is an important feature to identify the nature and presence of BVID in real-life applications. The results allowed an adequate optical fibre (OF) embedding location to be selected for BVID detection. The effect of small- and large-diameter OF on the impact resistance of the CFRP was compared.
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Zhou, Xiaohong, Xiaofang Zhou y Hui Zhang. "Optimizing Laser-Induced Voltage Signal in SnO2 Thin Films by Changing Oxygen Pressure". Advances in Materials Science and Engineering 2022 (15 de julio de 2022): 1–5. http://dx.doi.org/10.1155/2022/3303595.
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Laser-induced voltage (LIV) effect of the thin film can be applied for the laser energy measurement and millimeter-wave detection. The amplitude and corresponding velocity of LIV signals depended on the film material and preparation process. In the study, the effect of oxygen pressure on the LIV signals of SnO2 thin films was studied and got the surprised result that the maximum LIV peak reach about 4.02 V and response time with only 98 ns when oxygen pressure was 30 Pa. The crystal quality of the films was analyzed by X-ray diffraction (XRD) and LIV measurements, and a linear relationship between LIV peak voltage and laser energy was also disclosed. Those findings indicate that the laser energy/power meters designed with SnO2 thin film with optimized oxygen pressure would have the merits high precision, high sensitivity, and fast response.
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Veena, V. S., Sarita Vig, Nirupam Roy y Jayanta Roy. "High-velocity H i jet-like feature towards the SNR candidate G351.7–1.2". Monthly Notices of the Royal Astronomical Society: Letters 488, n.º 1 (19 de junio de 2019): L59—L63. http://dx.doi.org/10.1093/mnrasl/slz099.
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ABSTRACT We present the H i 21 cm spectral line and continuum observations of the Galactic supernova remnant (SNR) candidate G351.7–1.2 using the upgraded Giant Metrewave Radio Telescope. Strong absorption features are observed towards the H ii regions in the star-forming complex associated with G351.7–1.2. Along with H i emission towards the outer periphery of the SNR shell, we distinguish a high-velocity jet-like feature in the velocity range +40 to +52 km s−1 in H i. This unusual and highly collimated feature, with a projected length of ∼7 pc and an opening angle of 14.4°, is located towards the interior of the radio shell. This is the first report of a well collimated H i jet-like emission. The peculiar location and the detection of a γ-ray source towards the central peak of this H i jet suggests its plausible association with the SNR candidate.
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Giller, Cole A., Mustapha R. Hatab y Angela M. Giller. "Oscillations in Cerebral Blood Flow Detected with a Transcranial Doppler Index". Journal of Cerebral Blood Flow & Metabolism 19, n.º 4 (abril de 1999): 452–59. http://dx.doi.org/10.1097/00004647-199904000-00011.
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Although transcranial Doppler ultrasound (TCD) has been used to detect oscillations in CBF, interpretation is severely limited, since only blood velocity and not flow is measured. Oscillations in vessel diameter could, therefore, mask or alter the detection of those in flow by TCD velocities. In this report, the authors use a TCD-derived index of flow to detect and quantify oscillations of CBF in humans at rest. A flow index (FI) was calculated from TCD spectra by averaging the intensity weighted mean in a beat-by-beat manner over 10 seconds. Both FI and TCD velocity were measured in 16 studies of eight normal subjects at rest every 10 seconds for 20 minutes. End tidal CO2 and blood pressure were obtained simultaneously in six of these studies. The TCD probe position was meticulously held constant. An index of vessel area was calculated by dividing FI by velocity. Spectral estimations were obtained using the Welch method. Spectral peaks were defined as peaks greater than 2 dB above background. The frequencies and magnitudes of spectral peaks of FI, velocity, blood pressure, and CO2 were compared with t tests. The Kolmogorov-Smirnov test was used to further confirm that the data were not white noise. In most cases, three spectral peaks (a, b, c) could be identified, corresponding to periods of 208 ± 93, 59 ± 31, and 28 ± 4 (SD) seconds for FI, and 196 ± 83, 57 ± 20, and 28 ± 6, (SD) seconds for velocity. The magnitudes of the spectral peaks for FI were significantly greater ( P < 0.02) than those for velocity. These magnitudes corresponded to variations of at least 15.6%, 9.8%, and 6.8% for FI, and 4.8%, 4.2%, and 2.8% for velocity. The frequencies of the spectral peaks of CO2 were similar to those of FI with periods of 213 ± 100, 60 ± 46, and 28 ± 3.6 (SD) seconds. However, the CO2 spectral peak magnitudes were small, with an estimated maximal effect on CBF of (±) 2.5 ± 0.98, 1.5 ± 0.54, and 1.1 ± 0.31 (SD) percent. The frequencies of the blood pressure spectral peaks also were similar, with periods of 173 ± 81, 44 ± 8, and 26 ± 2.5 (SD) seconds. Their magnitudes were small, corresponding to variations in blood pressure of (±) 2.1 ± 0.55, 0.97 ± 0.25, and 0.72 ± 0.19 (SD) percent. Furthermore, coherence analysis showed no correlation between CO2 and FI, and only weak correlations at isolated frequencies between CO2 and velocity, blood pressure and velocity, or blood pressure and FI. The Kolmogorov-Smirnov test distinguished our data from white noise in most cases. Oscillations in vessel flow occur with significant magnitude at three distinct frequencies in normal subjects at rest and can be detected with a TCD-derived index. The presence of oscillations in blood velocity at similar frequencies but at lower magnitudes suggests that the vessel diameters oscillate in synchrony with flow. Observed variations in CO2 and blood pressure do not explain the flow oscillations. Ordinary TCD velocities severely underestimate these oscillations and so are not appropriate when small changes in flow are to be measured.
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Merline, W. J. "Precise Velocity Observation of K-giants: Evidence for Solar-Like Oscillations in Arcturus". International Astronomical Union Colloquium 170 (1999): 187–92. http://dx.doi.org/10.1017/s0252921100048545.
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AbstractHigh accuracy measurements of variations in the radial velocity of the K1 giant star Arcturus have been obtained. The observations span 5 years and have a point-to-point repeatability of 5 ms−1 and night-to-night stability of better than 20 ms−1. Velocity oscillations of Arcturus were discovered during the course of this work in 1986. Subsequent, extensive additional data, indicate that Arcturus is exhibiting global nonradial acoustic oscillations with characteristics similar to those occurring in the Sun.All observations were done using a radial velocity spectrometer, designed to search for extrasolar planets, at a dedicated facility of the University of Arizona on Kitt Peak. A dedicated facility was crucial to this work — because of the changing nature of the oscillations, many observing runs, over several years, were required to understand the star’s behavior. Continuous data sets as long as 30 days were acquired. Preliminary pulsation models were performed in collaboration of Art Cox at Los Alamos National Lab.The velocity power spectra are complicated and variable. There is substantial evidence that the variations are solar-like p-mode oscillations. At least 10 frequencies have been identified, over the range 8.3 to 1.7 days. A spectrum of evenly spaced modes is apparent, yielding a value for Δν0 ≈ 1.2 μ Hz. The average power spectrum peaks near 3 days. There is a broad envelope of power with a distribution reminiscent of that seen in the Sun. Both the mode spacing and the period of peak power are consistent with scaling from the Sun (Kjeldsen & Bedding 1995). The oscillations appear to undergo abrupt discontinuities and have phase coherence times of a few weeks. We interpret the driving to be due to stochastic excitation by convection.Recent observations of the G5 IV star η Boo by Brown et al. (1997) have failed to confirm the detection of p-mode oscillations reported by Kjeldsen et al. (1995) Thus, Arcturus may be one of the first stars known to exhibit solar-like oscillations. If other K-giant variables can be shown to exhibit similar oscillations, Arcturus may represent the prototype for a new class of variable stars. We know some other K-giants are variable on short time scales (Hatzes and Cochran 1994b; Edmonds & Gilliland 1996), but many are not (Horner 1996).
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Jáchym, Pavel, Ming Sun, Masafumi Yagi, Chong Ge, Rongxin Luo, Françoise Combes, Anežka Kabátová, Jeffrey D. P. Kenney, Tom C. Scott y Elias Brinks. "Non-star-forming molecular gas in the Abell 1367 intra-cluster multiphase orphan cloud". Astronomy & Astrophysics 658 (febrero de 2022): L5. http://dx.doi.org/10.1051/0004-6361/202142791.
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We report the detection of CO emission in the recently discovered multiphase isolated gas cloud in the nearby galaxy cluster Abell 1367. The cloud is located about 800 kpc in projection from the center of the cluster and at a projected distance of > 80 kpc from any galaxy. It is the first and the only known isolated “intra-cluster” cloud detected in X-ray, Hα, and CO emission. We found a total of about 2.2 × 108 M⊙ of H2 with the IRAM 30-m telescope in two regions, one associated with the peak of Hα emission and another with the peak of X-ray emission surrounded by weak Hα filaments. The velocity of the molecular gas is offset from the underlying Hα emission by > 100 km s−1 in the region where the X-ray peaks. The molecular gas may account for about 10% of the total cloud’s mass, which is dominated by the hot X-ray component. The previously measured upper limit on the star formation rate in the cloud indicates that the molecular component is in a non-star-forming state, possibly due to a combination of low density of the gas and the observed level of velocity dispersion. The presence of the three gas phases associated with the cloud suggests that gas phase mixing with the surrounding intra-cluster medium is taking place. The possible origin of the orphan cloud is a late evolutionary stage of a ram pressure stripping event. In contrast, the nearby ram pressure stripped galaxy 2MASX J11443212+2006238 is in an early phase of stripping and we detected about 2.4 × 109 M⊙ of H2 in its main body.
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Kupryashkin, I. F. y N. V. Sokolik. "ALGORITHM OF SIGNAL PROCESSING IN THE RADAR SYSTEM WITH CONTINUOUS FREQUENCY MODULATED RADIATION FOR DETECTION OF SMALL-SIZED AERIAL OBJECTS, ESTIMATION OF THEIR RANGE AND VELOCITY". Journal of the Russian Universities. Radioelectronics, n.º 1 (28 de febrero de 2019): 39–55. http://dx.doi.org/10.32603/1993-8985-2019-22-1-39-47.
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Nowadays the interest in search of ways of improving the efficiency of small radar cross-section aerial objects detection and localization rises against the background of widespread use of light and unmanned aerial vehi-cles. As a result, researchers pay attention to radar systems (RS) with continuous linear frequency modulation (linear FM) signal. The use of such signals gives the measurable opportunity to reduce radar system peak-speech power and to cut the cost and weightsize parameters of the RS. The paper observes low-power ground based radar implementation prospects for purposes of detection and estimation of motion rates of small-sized aerial objects. The proposed algorithm of radar signals processing enables to simplify the detection of such tar-gets. The paper reveals the structure and defines the steps of the algorithm. The fundamental for the algorithm under consideration is the method of the range-Doppler image composition of the scanned area using digital signal processing. The paper presents the results of the algorithm operation in the low-power RS of C-band radar, obtained by processing of quadrotor echo-signals during the real experiment. The results show successful solvation of the applied problem of detection and tracking on the small-sized aerial object with the radar cross-section equal to less than 0.5 m2 and the spectrum of secondary radiation characterized by the expressed multimodality. The results of the experiment validate the application of the algorithm and demonstrate the possibility of the algorithm implementation in design of portable RS and automated target acquisition centers for detecting and tracking of the small-sized aerial targets (both, single as multi agent) with the information display on operator control panel.