Short Observation Time Research Articles

Patient outcomes after electrical injury \u2013 a retrospective study

IntroductionPeople exposed to electrical injuries are often admitted to hospital for observation. Current evidence suggests that patients who have a normal ECG on admission after a low-voltage injury, with no loss of consciousness or initial cardiac arrest may be discharged home after a short observation time. Currently, there are no established standards for the duration of monitoring after electric shock, but 24 h of observation is the most commonly adopted approach. We carried out a retrospective study of patients admitted after electrical injuries to determine the in-hospital outcomes and 30-day mortality in these patients.MethodsWe performed a chart review of all patients with electrical injuries admitted to Østfold Hospital, Norway between the years 2001 and 2019, to determine in-hospital and 30-day mortality and the frequency of various cardiac and non-cardiac complications.ResultsMean age of 465 included patients (88% males) was 31 years. Of all injuries, 329 (71%) were work-related, 17 (3.7%) involved loss of consciousness. Furthermore, 29/437 (6.6%) were high voltage (> 1000 V), and 243/401 (60.6%) were transthoracic injuries.369 (79.4%) were discharged same day. None of the admitted patients died in hospital nor did any die within 30 days of admission, yielding a 30-day mortality of 0% (95% CI 0–0.8). At admission troponin was elevated in three (0.6%) patients, creatinine kinase (CK) in 30 (6.5%) and creatinine in six (1.3%). Electrocardiogram (ECG) abnormalities were described in 85 (18%) patients. No serious arrhythmias were detected.When comparing high- vs low-voltage or transthoracic vs other injuries, there were no significant differences between most of the outcomes, except for more ECG abnormalities in the transthoracic group, whereas more patients had elevated CK, and fewer discharged the same day in high-voltage injuries.ConclusionNo in-hospital nor 30-day mortality or serious arrhythmias were encountered in those who were assessed, regardless of the type of injury. Troponin and creatinine were rarely elevated. It seems that conscious patients admitted with a normal ECG following a low-voltage injury may safely be discharged home after a quick clinical assessment including ECG.

A pilot study of spray cryotherapy effects on airway secretions

Spray cryotherapy (SCT) is a new transbronchial approach that disrupts epithelial cells by freezing. However, there are limited data addressing the effect of SCT on airway secretion. The aim of this study was to evaluate if SCT effect on airway secretion and the possible mechanism in canines. Fifteen labradors were randomly scheduled SCT or sham operation. Six labradors were scheduled SCT for a short-time observation, and six for a long-time observation, the remaining three received sham operation as control. Lung tissues were harvested for PAS staining. Mucin, MUC5AC and acetylcholine in bronchoalveolar lavage fluid (BALF) were analyzed by enzyme-linked immunosorbent assay (ELISA). CHRM3 and Mucin 5AC (MUC5AC) expressions in the lung tissues were analyzed by immunohistochemistry. MUC5AC mRNA expression was analyzed by rt-PCR. From 0 day to 30 days after SCT, the ratio of PAS positive cells to total bronchial epithelial cells, the average optical density of MUC5AC + by immunohistochemistry, the protein expression of MUC5AC, acetylcholine in BALF decreased compared with that of control group (p < 0.05). The average optical density of CHRM3+ by immunohistochemistry were decreased from 0 day to 7 days after SCT (p < 0.05) compared with control group. In conclusion, SCT was able to reduce the PAS-, MUC5AC- and CHRM3-positive cells in the lung tissue and acetylcholine in BALF, suggesting that SCT may prove to be a beneficial way in mucus excessive production in airway and acetylcholine-CHRM3 pathway may one possible mechanism.

Improvement of the Treatment Results in Childhood Acute Myeloid Leukemia in Poland from 1983 to 2017

Introduction: Acute myeloid leukemia (AML), heterogeneous group of malignant neoplasm of hematopoietic system, comprises of 15% of all leukemias in children. Standardized AML-BFM based protocols of the treatment of AML introduced in Poland from 1983 enabled successive improvement of survival rates. Before 1983 only 10% of children with AML in our country had chance to survive.The aim of the study was analysis of the treatment results in five consecutive periods: AML-PGPLBC83 (1983-1993, group I), AML-PGPLBC94 (1994 -1997, group II), AML-PGPLBC98 (1998-2004, group III), AML-BFM2004 Interim (2005-2014, group IV ) and AML-BFM 2012 (2015-2017, group V).Patients: Eight hundred and two patients diagnosed with AML from 1983 to 2016 in Poland were eligible for evaluation (187, 74, 149, 351 and 41 respectively in group I, II, III, IV and V). Patients with acute promyelocytic leukemia, AML in Down syndrome and secondary AML were excluded from analysis. Median observation time was 128, 73, 119, 65 and 12 months in consecutive groups respectively.Results: Complete remission rate in the groups I to V was: 72%, 66%, 84%, 87% and 83%, respectively. Percentage of early deaths (before 42. day of the treatment) was 22%, 14%, 5% , 4%, and 7% respectively. Non-responders comprised of 6% of all patients in the first group, 18% in the second, 10% in the third, 8% in the fourth and 9% in the last group. Among patients who achieved remission in the group I 16% died in remission and 42% relapsed, in the group II 16% died in remission and 33% relapsed, in the group III 11% died in remission and 40% relapsed, in the group IV 7% died in remission and 34% relapsed, in the last group 3% died in remission and 9% relapsed. Probability of the 5-years overall survival (OS) was 33%, 38%, 53% and 63% in four consecutive periods, respectively. Probability of the 5-years event free survival (EFS) was 32%, 36%, 46% and 49%, respectively in groups I-IV. Probability of relapse free survival (RFS) in patients who achieved remission was 51%, 62%, 55%, 62% respectively in groups I-IV. Because of too short observation time in the last group (V), 12-months survival rates were counted: OS - 74% (compared to 50%, 52%, 68% and 80% in groups I-IV), EFS - 70% (compared to 34%, 44%, 58%, 66% in the groups I-IV) and RFS - 89% (67%, 74%, 72%, 78% in the groups I-IV).Discussion: Systematic improvement of the treatment results, increase in proportion of achieved remission and reduction of early deaths and deaths in remission in the four consecutive groups treated from 1983 to 2015 was observed. The progress was achieved by modification of protocols with more accurate stratification to the risk groups, development of supportive care and gaining experience in reducing number of toxic deaths. Unfortunately proportion of relapses was still high. Therefore in 2015 new treatment protocol AML-BFM 2012 with stratification to the risk group based on cytogenetic and molecular genetics changes, as well as treatment responses was introduced. Number of patients in the group V treated with that protocol is low with short observations time however preliminary results seem to be encouraging. Further progress in AML therapy seems to be possible due to further oncology centers' cooperation within large international study groups. DisclosuresNo relevant conflicts of interest to declare.

Prescribing Tamoxifen in Patients With Mood Disorders: A Systematic Review of Potential Antimanic Versus Depressive Effects.

Tamoxifen is a selective estrogen receptor modulator widely used for treatment and prevention of estrogenic receptor-positive breast cancer. Tamoxifen is an object of growing interest in psychopharmacology as an antimanic drug, because it inhibits the protein kinase C, a molecular target of bipolar disorder. Consistently, the potential depressive effect of tamoxifen has been repeatedly reported. This article systematically reviews studies examining tamoxifen impact on mood, exploring either its potential therapeutic use as antimanic agent or its potential depressive effect. Eight studies explored tamoxifen antimanic properties, all, but one, reported a rapid and efficacious antimanic action. As to the depressive effect, 9 cohort studies emerged among which 4 pointed out an increased risk of depression. Seven case reports described the onset or exacerbation of depressive episodes besides 1 case series study reported a high rate of depressive symptoms. In addition, 1 case report study described a tamoxifen-induced manic episode. The present review highlights tamoxifen treatment as a possible trigger of mood symptoms onset or exacerbation in vulnerable patients. Accordingly, patients with a history of mood disorders may require a close clinical surveillance during tamoxifen use. At the same time, the use of tamoxifen as an antimanic agent in psychiatric settings requires caution, as available evidence came from small-sample studies with short observation time. More studies are needed to define how long-term tamoxifen use may affect the course of bipolar disorder.

High-temperature diffraction experiments and phase diagram of ZrO2 and ZrSiO4

Abstract High-temperature X-ray diffraction (XRD) experiments up to T = 2710 °C have been performed on ZrSiO4 and ZrO2 powders, using the container-less levitation technique. A two-dimensional imaging plate (IP) detector was used for short-time observation. The diffraction data in a wide area was projected in one dimension. The unit cell parameters, thermal expansions, and c/a ratios for ZrSiO4 (space group I41/amd and Z = 4), tetragonal ZrO2 (space group P42/nmc and Z = 2) and cubic ZrO2 (space group F m 3 ‾ m $Fm3&amp;#x203e;{}m$ and Z = 4) were measured to understand the high-temperature behaviors. The transition temperature between tetragonal and cubic ZrO2 was specified to be between 2430 and 2540 °C. The pre-transitional behavior was observed around 2200 °C. As no clear change in unit cell volume is evident, the phase boundary between the tetragonal and the cubic phase has been shown to be a positive slope. The ZrO2 and ZrO2–SiO2 phase diagrams are proposed based on the chemical composition and the crystal structure.

Sparse time‐frequency analysis for aircraft target classification with low sampling rate and short observation time

AbstractThe traditional time‐frequency analysis (TFA) techniques are instruments for target classification, which can reflect the feature of the target in the time‐frequency domain. However, it will lead to a serious decrease in the recognition accuracy as the decline of the sampling rate. To ease this problem, in this article, the sparse time‐frequency feature analysis (STFFA) is implemented for aircraft classification, and the genetic algorithm is adopted to solve the sparse problem quickly for saving time. Firstly, the sparse time‐frequency decomposition and recovery signal are obtained by matching pursuit. Then, three novel kinds of aircraft features are extracted from the sparse time‐frequency decomposition, which are sparse recovery time‐frequency entropy (SRTFE), frequency entropy by time, and first‐order sparse time‐frequency moment. Thus, the feature combination modes based on the three features are applied to realize the classification of aircraft and compared with the traditional TFA techniques. Besides, a support vector machine is also used to classify the three kinds of aircraft. The accuracy and efficiency of the STFFA method have been investigated by employing the parametric model data and electromagnetic scattering model simulated trials. Furthermore, in contrast to the traditional TFA instrument, our method can reach a recognition accuracy of more than 90% from the numerical experiment results, which demonstrates that the feature extraction by sparse time‐frequency analysis improves the accuracy of aircraft classification under a low sampling rate.

Radiosensitization using hydrogen peroxide in patients with cervical cancer.

The purpose of the present study was to analyze the feasibility and safety of radiosensitization using hydrogen peroxide for cervical cancer. In superficial tumors, breast cancer and hepatocellular carcinoma, the safety and effectiveness of radiosensitization has been reported; to the best of our knowledge, however, there are no reports on cervical cancer. A total of 20 patients with cervical cancer were recruited. Inclusion criteria were as follows: Patients who required radical external beam radiotherapy (RT); ineligible for or refused brachytherapy; age, ≥20 years; no hematogenous metastasis; Eastern Cooperative Oncology Group Performance Status up to 2; and had not undergone prior treatment. Hydrogen peroxide was used twice a week in combination with RT. A 3% hydrogen peroxide solution-soaked gauze was inserted into the vagina during RT. A total of 45 Gy was delivered in 25 fractions to the whole pelvis with a boost of 10 Gy in 5 fractions if pelvic or para-aortic metastatic lymph nodes were observed. Ultimately, 18 patients were evaluated. Among the 17 patients (excluding one patient with tumor in situ), the one- and two-year overall survival rates were both 90% in patients with stage I/II and 86% in stage III/IV cervical cancer. The adverse events were well tolerated with no severe acute or late adverse events. Although limited by small sample size, short observation time and low radiation dose, the present study demonstrated that radiosensitization treatment may be an option for patients who cannot undergo brachytherapy. The study was retrospectively registered at the university hospital medical information network center (no. UMIN000039045) on January 6, 2020.

Rates and Risk Factors for Interval Gastric Cancers at Screening Gastroscopy.

Interval gastric cancers (GCs) can be encountered during screening gastroscopy. This study investigated the rate of interval GCs and their risk factors. We retrospectively investigated subjects who underwent screening gastroscopy from 2005 to 2017 in a university hospital and were diagnosed with GC. Subjects were grouped based on their endoscopic images and descriptive results into interval GC and initially diagnosed GC groups. Interval GCs were defined when endoscopic results within the previous 3 years were negative for GC. The clinico-pathological characteristics of the groups and risk factors for interval GCs were evaluated. Of 54 724 subjects who underwent screening gastroscopy, 234 were diagnosed with GC, of which 43 were interval GCs. The rate of interval GCs was 18.4% (43/234, mean age 61.6 years). Interval GCs were smaller than initially diagnosed GCs (1.6 vs 1.9 cm, P = .011). They were located in the low-to-mid-body in 44.2%, antrum in 48.8%, and high body and cardia in 7%. Their observation time was shorter (248.74 vs 410.64 sec, P = .032). In multivariate analysis, they were associated with short observation time (odds ratio [OR] 0.99, 95% CI 0.994-0.998, P < .001) and location in the low-to-mid-body (OR 2.12, 95% CI 1.071-4.181, P = .031), although differentiation, ulcerated type, metaplasia, Helicobacter pylori infection, and endoscopists' experience were not associated with interval GCs. The rate of interval GCs was significant during screening gastroscopy. They might be reduced by increasing observation time, focusing on smaller lesions, and observing the low-to-mid-body of the stomach more carefully.

Adaptive Spectral Doppler Estimation Based on the Modified Amplitude Spectrum Capon.

In conventional ultrasound systems, the compromise between frequency and temporal resolution limits the quality of the spectrograms and the ability to track fast blood flows. The main objective of this study was to identify a method that could reduce spectral broadening over time by reducing the observations and improving the spectral resolution and contrast. This problem is more pronounced in the process of imaging at higher blood velocities when using a short Doppler signal observation window (OW) in adaptive methods. The proposed adaptive technique, which is based on the covariance matrix Eigen space and the amplitude spectrum Capon (ASC) algorithm, managed to improve the spectral resolution and contrast compared with other adaptive algorithms within a shorter observation time, and it offered a narrower power spectrum and a more accurate spectrogram over time in combination with a coherence-based post filter. All methods were tested through various simulations. First, an analysis was carried out by simulating the femoral artery flow and the time-independent parabolic flow using the Field II simulator. Then, the performance of the proposed method was evaluated under more realistic conditions using a computational fluid dynamics simulation of complex flow fields in a carotid bifurcation model. Afterward, in vivo clinical data on the hepatic vein were used to validate the proposed method. Finally, the accuracy of the velocity estimated by different methods was evaluated through a mean-square-error assessment. Not only could the proposed method show significant improvements using extreme small OWs, N=[2, 4] , in the simulated data in terms of frequency resolution and contrast, but it also managed to offer an improvement of 74%, 73.3%, 22.2%, and 50% in frequency resolution, and an increase of 96.5, 90.2, 49, and 31.5 dB in contrast using in vivo clinical data compared with the Capon, amplitude and phase estimation (APES), projection-based Capon, and projection-based APES, respectively, for the OW of N=4 .

Basic performance of a spatial autocorrelation method for determining phase velocities of Rayleigh waves from microtremors, with special reference to the zero-crossing method for quick surveys with mobile seismic arrays

SUMMARY We theoretically and empirically demonstrate the usability of the zero-crossing method for quick microtremor surveys in earthquake engineering (i.e. microtremor array surveys), namely shallow (&amp;lt; a few kilometres) surveys with small-scale (&amp;lt; 1 kilometre in radius) mobile seismic arrays with a short observation time (&amp;lt; a few hours). The zero-crossing method is a type of spatial autocorrelation (SPAC) method that determines phase velocities based on multiple frequencies at which the SPAC coefficient curve crosses zero. It is theoretically shown that the zero-crossing method is robust against incoherent noise and that the use of the first zero crossings (i.e. those at the lowest frequencies) is more robust against inadequate conditions of the microtremor wavefield than the use of later zero crossings (i.e. those at higher frequencies). We used microtremor array data with maximum array radii and observation durations of 400 m and 120 min on average, respectively, at 445 observation sites in the Kanto Plain, Japan, for validating the practicality of using the first zero crossings. As an illustration of the robustness against low signal-to-noise ratios (SNRs), we show that with the zero-crossing method, low-sensitivity (i.e. low-SNR) seismometers provide the same analysis results as those obtained with high-sensitivity seismometers, even when the power spectral densities for the low-sensitivity seismometers are close to the self-noise level. We then show that a reference phase velocity dispersion curve (RPVDC), created mainly based on the first zero crossings at each site, has a spatial distribution that well corresponds to the geology and topography and is consistent with that obtained in a previous study. We inverted five RPVDCs to model 1-D S-wave profiles and validated them using S-wave profiles obtained from velocity logs at nearby deep (e.g. hundreds of metres) boring wells. The accuracy of phase velocities at the later zero crossings for three-sensor/four-sensor arrays and all zero crossings for two-sensor arrays are statistically examined (maximum of 9805 data) based on a comparison with the RPVDCs. The disadvantage of the zero-crossing method is that it can only provide information on phase velocities at discrete wavelengths up to a maximum wavelength of 2.6r (i.e. corresponding to the first zero-crossing point), where r is the radius of a seismic array. Therefore, the RPVDCs were then used to examine the upper limit of the analysable wavelength ranges for the conventional SPAC method for microtremor array surveys. Based on a few hundred three-sensor/four-sensor arrays, it was found that for arrays with radii larger than several tens of metres, three-quarters of the upper limit wavelengths (ULWs) stayed within 5r. For arrays with radii smaller than this value, the ULWs strongly depended on the array radius; the ULWs dramatically increased with decreasing array radius. For example, for arrays with an r value of 0.6 m, half of 336 data ranged between 26r and 54r, and the maximum ULW reached 186r. This strong size dependence can be explained by differences in SNR.

The 17-year outcome of 62 adult patients with longstanding eating disorders-A prospective study.

Although studies with short and intermediate observation time suggest favorable outcomes in regard to eating disorders (ED), there is limited knowledge on long-term outcomes. The present study aimed to investigate the 5- and 17-year outcome of adult patients with longstanding ED who were previously admitted to an inpatient ED unit. ED diagnoses and recovery, comorbid and general psychopathology, along with psychosocial functioning and quality of life were evaluated. Sixty-two of the 80 living patients (78% response rate) with anorexia nervosa (n = 23), bulimia nervosa (n = 25), or other specified feeding or eating disorders (n = 14) at admission were evaluated. The mean age at the 17-year follow-up point was 46.2 (SD 7.5). The Eating Disorder Examination (EDE) was used to assess recovery. The Mini International Neuropsychiatric Interview (M.I.N.I.) and self-report instruments provided additional information. There was a significant reduction in patients fulfilling criteria for an ED from the 5-year to the 17-year follow-up, meanwhile recovery rates were stable. A total of 29% of the patients were fully recovered and 21% were partially recovered while the remaining 50% had not recovered. No significant changes were found in any self-report measures and more than 70% had a comorbid disorder at both assessments. The findings illustrate the protracted nature of ED for adults with longstanding ED. A long illness duration prior to treatment is unfortunate and early detection and treatment is advisable.

Time-motion analysis in elite female Wushu Sanda athletes according to competitive phases and weight categories

Introduction: Wushu Sanda is a Chinese combat sport. Objective: To measure the time-motion structure of elite female wushu sanda athletes during the 13th World Wushu Championships in different weight divisions (light, middle, and heavy categories) and competition phases (eliminatory, quarterfinals, semifinals and finals). Material and methods: Fifty-five female athletes from 31 countries participated in 46 matches during the competition. All 46 matches, accounting 95 rounds, 35 in light, 25 in middle and 35 in heavyweight divisions, took part in the study. Matches were analyzed using the software Kinovea™. Each match was reproduced in slow motion (50%) twice; therefore, one athlete was observed each time to ensure that all activities would be registered, totalizing 92 observations (46 matches, 2 observations per match). We registered the time in observation, preparation, interaction, effort, pause, high-intensity and low-intensity activities. Results: Descriptive data showed an effort:pause ratio of 2.2:1, a high:low intensity efforts ratio of 1:1.3, and mean observation-preparation-interaction times of 4.5-1.2-4.2 seconds. When comparing by weight category, heavyweight categories had higher total fighting time per round than the light and middle categories. Also, heavyweight categories had longer preparation and interaction mean-time; and referee interruption time frequency, total and mean times than the light and middle categories. Total pause time was also higher for heavyweights. According to the competitive phase, semifinal matches had shorter observation times than eliminatory and final matches. Also, semifinal matches had lower low-intensity time than quarterfinals and finals. Conclusions: Wushu sanda is an intermittent combat sport, and female athletes present some time-motion differences according to weight division and competitive phase.

Impact of turbulence-induced asymmetric propagators on the accuracy of phase-contrast velocimetry

Phase-contrast magnetic resonance velocimetry (PC-MRI) has been widely used to investigate flow properties in numerous systems. In a horizontal cylindrical pipe (3 mm diameter), we investigated the accuracy of PC-MRI as the flow transitioned from laminar to turbulent flow (Reynolds number 352–2708). We focus primarily on velocimetry errors introduced by skewed intra-voxel displacement distributions, a consequence of PC-MRI theory assuming symmetric distributions. We demonstrated how rapid fluctuations in the velocity field, can produce broad asymmetric intravoxel displacement distributions near the wall. Depending on the shape of the distribution, this resulted in PC-MRI measurements under-estimating (positive skewness) or over-estimating (negative skewness) the true mean intravoxel velocity, which could have particular importance to clinical wall shear stress measurements. The magnitude of these velocity errors was shown to increase with the variance and decrease with the kurtosis of the intravoxel displacement distribution. These experimental results confirm our previous theoretical analysis, which gives a relationship for PC-MRI velocimetry errors, as a function of the higher moments of the intravoxel displacement distribution (skewness, variance, and kurtosis) and the experimental parameters q and Δ. This suggests that PC-MRI errors in such unsteady/turbulent flow conditions can potentially be reduced by employing lower q values or shorter observation times Δ.

Sparse Imaging for Spinning Space Targets With Short Time Observation

Inverse synthetic aperture radar (ISAR) imaging is an important technique for moving target identification and classification. For the space spinning targets, a long-time observation is required to estimate the spinning parameter in the conventional ISAR imaging methods. However, for the advanced multifunctional radar, which is used for multi-target surveillance, a long-time observation for only one target is the loss outweighs the gain. To decrease the observation time, we propose a novel imaging method for spinning space targets with short time observation in this paper. Firstly, we build the imaging model by using the azimuth rotation angle caused by the spinning motion rather than the translation motion to obtain the azimuth resolution. Secondly, we utilize the orthogonal coding signals with different delays to obtain enough equivalent pulses in the short observation time. Moreover, since the equivalent pulses are block-missing to avoid overlapping of the transmitting duration and the receiving duration, we transform the imaging problem to the compressed sensing (CS) problem and solve it by modifying the Smoothed L0-norm (SL0) algorithm. Finally, both the simulations and the experiments on real data are shown to demonstrate the validity of the proposed method. Since the observing time of the proposed method only needs to cover a small percentage of one spinning period, the proposed method can be used in multi-target surveillance such as satellites and space debris.

Forward-Looking Geometric Configuration Optimization Design for Spaceborne-Airborne Multistatic Synthetic Aperture Radar

Spaceborne-airborne multistatic synthetic aperture radar (SA-MuSAR) has the ability to provide high-resolution forward-looking imagery for receivers, but it relies on careful design of the geometric configuration (GC). In this article, a forward-looking GC optimization design method is proposed to obtain a high-quality fused image with limited observation time. First, the relationship between the spatial resolution and GC is illustrated by the wavenumber spectrum distribution of SA-MuSAR. Second, GC evaluators depending on the distribution of multiple wavenumber spectrum data are proposed. The GC design problem of coherent SA-MuSAR is transformed into a constrained multiobjective optimization problem. An intelligent evolutionary algorithm is adopted to optimize the wavenumber spectrum distribution. With the proposed method, high-quality forward-looking imagery can be obtained with a short observation time. Numerical simulations are carried out to verify the effectiveness of the proposed method.

Accurate Dynamic Phasor Estimation by Matrix Pencil and Taylor Weighted Least Squares Method

Out-of-band interference (OOBI) test is a bench-mark test for M-class phasor measurement units (PMUs) in IEEE/IEC 60255-118-1-2018 and C37.118.1a-2014. Because of the spectral interference produced by interharmonic, it is difficult for dynamic phasor estimators to satisfy the OOBI test requirements with a short observation time. To this end, this article proposed a Taylor weighted least squares (TWLS) method based on the matrix pencil for the dynamic phasor estimation of the OOBI contaminated signal. The proposed method first applies the matrix pencil algorithm to obtain rough estimations for the frequencies of the fundamental component and other components (i.e., harmonics, subharmonics, and interharmonics) within a few cycles. Then, the TWLS method was adopted to acquire more accurate estimations of the dynamic phasor and frequencies. The effectiveness of the proposed method is validated by simulations under steady and dynamic conditions that follow the requirements of the IEEE standard.

A Novel Rapid GNSS Network Solution in Mountainous Region Monitoring considering the Tropospheric Delay at Ground Points

Due to the short peak observation time of global navigation satellite systems (GNSS), the accuracy of the tropospheric delay estimation and the positioning are poor. In this study, a rapid GNSS network solution for mountainous regions is presented. The high‐precision tropospheric delay at ground points is obtained from long‐term ground observation data and used as a priori constraint in the double‐difference equation of short‐time synchronous peak observations to realize rapid and high‐precision positioning. Chinese mountain survey networks with large elevation gradient (1000~2000 m) were selected for the experimental verification of the proposed method. The results show that the rapid peak positioning method weakened the effect of the residual tropospheric delay caused by the elevation difference, significantly improving the accuracy and reliability of the results. The positioning accuracy of the peak in upward direction was better than 1.1 cm, which meets the requirements of rapid short‐span (~1 h) high‐precision monitoring and achieves 24 h positioning accuracy. Compared with the traditional solution strategy, the precision of the method with respect to the north (N), east (E), upward (U), and zenith tropospheric delay (ZTD) significantly improved. The accuracy of U improved by more than 47%. Therefore, based on the high accuracy and reliability, information of ground stations can be fully utilized to significantly reduce the peak observation time and the operation costs of surveys in mountain regions.

Estimation Bounds of Beat Signal in the R-Mode Localization System

The R-Mode system is a terrestrial navigation system currently under development, which exploits existing means of medium frequency radio transmission. The positioning and timing performance depends on the estimation of the signals’ phase offset, from which the ranging information is derived. For an analogous problem such as the single-tone phase estimation, the Cramer-Rao bound (CRB) describes the minimal achievable performance in the mean squared error sense. For R-Mode, the problem involves the estimation of the phase offset for a beat signal, which can be described as the difference of phase estimation for the two aiding carriers next to the signal. This estimates are not statistically independent for finite observation, as we show in this paper. The effect becomes stronger for short observation times, which are important for a near real time application. In this contribution, we are interested in phase offset estimation for the signal models relevant to R-Mode: a beat signal and a beat signal combined with an MSK signal. A closed-form lower CRB is proposed for the aforementioned signal models phase estimation, as well as a generalization of the bound for the phase-difference estimation. Based on this derivation, optimized bit sequences are shown to improve performance of the estimates. The validity of the proposal is verified based on a simulation setup. Measurements acquired during a measurement campaign serve to further justify the usefulness of the bound. Some possible applications of such a bound are R-Mode coverage prediction and the associated phase estimators’ performance.

A rapid coarse-grained blind wideband spectrum sensing method for cognitive radio networks

Spectrum sensing aims to sense the potential spectrum resources available in the cognitive radio environment. It is also the premise of spectrum management and spectrum sharing in cognitive radio systems. To perceive the primary user’s activity and make full use of spectrum holes, rapid detection of a broad frequency span is an essential part of cognitive radio technology. Reducing the observation time for the data collection, the data storage requirements, and hardware/software computational complexity are urgent and challenging issues in wideband spectrum sensing. High accuracy power spectral density estimation is not the primary requirement; of course, the accuracy must be controlled within the appropriate range and can support the primary user activity’s determination. This paper proposes a sub-Nyquist wideband spectrum sensing method based on compressive covariance sensing for the rapid wideband spectrum sensing. Compared with the traditional Nyquist-rate method, this method can use low-speed ADC to detect wideband signals and effectively control the observation time and computational complexity. This paper’s main contributions include: (1) developing a sub-Nyquist sampling structure based on the multi-coset sampling banks, (2) proposing a coarse-grained power spectral density estimation method for wideband spectrum sensing with short observation time and low complexity. Simulations show that the proposed method exhibits this method is suitable for fast spectral detection. At the same time, the error of spectrum analysis is basically within the acceptable range.

Partial responses to ibrutinib in Waldenström macroglobulinaemia - good enough?

Partial responses to ibrutinib in Waldenström macroglobulinaemia - good enough?