Weak Pulse Research Articles

Dwarf Pulses of 10 Pulsars Detected by FAST

How pulsars radiate is a long-standing problem. Detailed polarization measurements of individual pulses shed light on currently unknown emission processes. Recently, based on supersensitive observations, dwarf pulses have been recognized as weak narrow pulses often appearing during the nulling state. In this study, we report the detection of dwarf pulses from 10 pulsars, PSRs B0525+21, B1237+25, J1538+2345, J1824−0127, J1851−0053, B1901+10, J1939+10, B1944+17, B2000+40, and J2112+4058, based on observations conducted with the Five-hundred-meter Aperture Spherical radio Telescope. Dwarf pulses of five pulsars are clearly discernible in the two-dimensional distribution of pulse intensity and pulse width. For the other five pulsars, PSRs J1538+2345, J1824−0127, J1939+10, B2000+40, and J2112+4058, only a few dwarf pulses are detected from pulse stacks. The dwarf pulses can emerge in both cone and core emission components for PSR B1237+25, and the polarization angles of these dwarf pulses are mostly in the orthogonal polarization mode of normal pulses for PSR B1944+17. In general, pulsars with detected dwarf pulses tend to be located within the “death valley” region of the distribution of pulsar periods and period derivatives.

Circuit design of a novel front readout circuit for SiC neutron detector with leakage current compensation

Radiation detectors have broad application prospects in environmental radiation monitoring, radiation source identification, biomedical imaging, space exploration, astrophysics, other radiation detection and imaging fields. Among the third generation semiconductors, the properties of 4H-SiC are more suitable for making high-temperature and strong radiation neutron detectors. SiC materials have become a current research hotspot. In this paper a special readout integrated circuit is designed for the extremely weak current pulse signal output by SiC trench neutron detector. A leakage current compensation circuit is designed for the influence of leakage current on charge sensitive amplifier(CSA) output baseline. The noise of CSA output is analyzed and the noise minimization is carried out. The circuit can quickly respond to the input signal and extract the energy and time information. The circuit is designed based on the DB Hitek 0.18μm CMOS process model. The layout design is achieved and the post-simulation is completed. Simulated results show that the equivalent input charge range of the system is about 2fC ∼ 20fC. The charge conversion gain is 88mV/fC. The nonlinear error is within 1.6 %. Moreover, the equivalent noise charge is 22e-. The circuit has the advantages of high gain, high linearity and low noise. Therefore, the circuit can effectively adapt to the characteristics of the charge signal output from SiC trench neutron detectors and amplify the output charge signal.

Biexponential I = 3/2 Spin-Lattice Relaxation in the Solid State: Multiple-Quantum 7Li NMR as a Probe of Fast Ion Dynamics.

Spin-lattice relaxation measurements are used in 7Li NMR studies of materials of potential use in solid-state Li-ion batteries as a probe of ion mobility on a fast (nanosecond to picosecond) time scale. The relaxation behavior is often analyzed by assuming exponential behavior or, equivalently, a single T1 time constant. However, the spin-lattice relaxation of spin I = 3/2 nuclei, such as 7Li, is in general biexponential; this is a fundamental property of I = 3/2 nuclei and unrelated to any compartmentalization within the solid. Although the possibility of biexponential 7Li (and other I = 3/2 nuclei) spin-lattice relaxation in the solid state has been noted by a number of authors, it can be difficult to observe unambiguously using conventional experimental NMR techniques, such as inversion or saturation recovery. In this work, we show that triple-quantum-filtered NMR experiments, as previously exploited in I = 3/2 NMR of liquids, can be used in favorable circumstances to observe and readily quantify biexponential 7Li spin-lattice relaxation in solids with high ion mobility. We demonstrate a triple-quantum-filtered inversion-recovery experiment on the candidate solid electrolyte material Li2OHCl at 325 K, which has previously been shown to exhibit fast ion mobility, and we also introduce a novel triple-quantum-filtered saturation-recovery experiment. The results of these solid-state NMR experiments are less straightforward than those in liquids as a consequence of the unwanted direct excitation of triple-quantum coherences by the weak (compared with the unaveraged 7Li quadrupolar interaction) pulses used, but we show that this unwanted excitation can be accounted for and, in the example shown here, does not impede the extraction of the two 7Li spin-lattice relaxation times.

UV-induced resonant excitations of electrons near the Brillouin zone boundary in solid high harmonic generation

Abstract We propose a novel mechanism to manipulate the electron dynamics at the boundary of the Brillouin zone (BZ) through resonant excitation induced by ultraviolet (UV) laser pulses in solid high harmonic generation (HHG). When adding weak UV pulses to a stronger mid-infrared (MIR) driving field, we show that UV pulses with specific wavelengths generate a resonant excitation zone around the Γ point in k − space, which facilitates the interband transition of electrons in the BZ boundary region. The scheme is not only significant for achieving higher harmonic yield, but also exhibits strong robustness at a relatively low MIR driving intensity due to the inherent manipulation of UV pulses for interband dynamics of BZ boundary electrons. The semiclassical four-step model is adopted to elucidate underlying physics.

Impact of sex differences on the feasibility and safety of distal radial access for coronary procedures: a multicenter prospective observational study.

Conventional transradial access in women is associated with a lower success rate and a higher incidence of spasm compared to men. To date, the effect of sex on the performance of distal radial access (DRA) has not been fully elucidated. The aim of this study was to assess the impact of sex on catheterization success and other performance parameters of DRA procedures. This is a prospective three-center observational study. From August 2020 to September 2022, data from all consecutive patients who underwent DRA for coronary procedures were collected. A total of 868 procedures were registered and stratified into two groups according to sex: women (n = 258) and men (n = 610). Female patients had less favorable baseline characteristics than male patients in terms of absent or weak pulse (29% vs. 17%; P < 0.001), distal radial diameter (2.2 ± 0.3 vs. 2.4 ± 0.4 mm; P < 0.001) and proximal radial diameter (2.5 ± 0.7 vs. 2.7 ± 0.7 mm; P = 0.001). No differences in success rates were found in women compared to men (94.2% vs. 96.6%; P = 0.135), with a higher presence of arterial spasm in women (5.8% vs. 3.0%; P = 0.044). The preprocedural ultrasound evaluation was the only predictor of DRA success [odds ratio = 20.0 (4.739-83.333); P < 0.001]. In patients undergoing coronary procedures, the success rate of DRA was high regardless of sex, with a higher incidence of arterial spasm in women.

Maximizing Four-Wave Mixing in Four-Subband Semiconductor Quantum Wells with Optimal-Shortcut Spatially Varying Control Fields

In the present article, we derive optimal spatially varying control fields, which maximize the four-wave mixing efficiency in a four-subband semiconductor asymmetric double quantum well, following analogous works in atomic systems. The control fields coherently prepare the medium, where a weak probe pulse is propagated and eventually converted to a signal pulse at the output. The optimal fields, which maximize the conversion efficiency for a given propagation length, are obtained by applying optimal control theory to a simplified form of propagation equations but are tested with numerical simulations using the full set of Maxwell–Schrödinger equations, which accurately describe the propagation of light pulses in the medium. For short propagation distances, the proposed optimal scheme outperforms a simpler spatially changing control protocol that we recently studied, while for larger distances, the efficiency of both protocols approaches unity. The present work is expected to find application in frequency conversion between light beams, conversion between light beams carrying orbital angular momentum, and nonlinear optical amplification.

A Novel Wind Turbine Rolling Element Bearing Fault Diagnosis Method Based on CEEMDAN and Improved TFR Demodulation Analysis

Among renewable energy sources, wind energy is regarded as one of the fastest-growing segments, which plays a key role in enhancing environmental quality. Wind turbines are generally located in remote and harsh environments. Bearings are a crucial component in wind turbines, and their failure is one of the most frequent reasons for system breakdown. Wind turbine bearing faults are usually very localized during their early stages which is precisely when they need to be detected. Hence, the early diagnosis of bearing faults holds paramount practical significance. In order to solve the problem of weak pulses being masked by noise in early failure signals of rolling element bearings, a novel fault diagnosis method is proposed based on the combination of complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and an improved TFR demodulation method. Initially, the decomposition of vibration signals using CEEMDAN is carried out to obtain several intrinsic mode functions (IMFs). Subsequently, a novel KC indicator that combines kurtosis and the correlation function is designed to select the effective components for signal reconstruction. Finally, an innovative approach based on the continuous wavelet transform (CWT) for multi-scale demodulation analysis in the domain of time–frequency representation (TFR) is also introduced to extract the envelope spectrum. Further fault diagnosis can be achieved by the identification of the fault characteristic frequency (FCF). This study focuses on the theoretical exploration of bearing faults diagnosis algorithms, employing modeling and simulation techniques. The effectiveness and feasibility of the proposed method are validated through the analysis of simulated signals and experimental signals provided by the Center for Intelligent Maintenance Systems (IMS) of the University of Cincinnati and the Case Western Reserve University (CWRU) Bearing Data Center. The method demonstrates the capability to identify various types of bearing faults, including outer race and inner race faults, with a high degree of computational efficiency. Comparative analysis indicates a significant enhancement in fault diagnostic performance when compared to existing methods. This research contributes to the advancement of effective bearing fault diagnosis methodologies for wind turbines, thereby ensuring their reliable operation.

Knob of adjusting light group velocity in an inhomogeneously broadened degenerate two-level atomic medium by a magnetic field

We proposed a simple model for investigating subluminal and superluminal light propagation via an external magnetic field in an inhomogeneously broadened degenerate two-level atomic medium. We show that a magnetic field can be utilized as a knob to control the absorption/dispersion properties and group index of the medium. By changing the magnitude and reversing the direction of the magnetic field, the positive group index is converted to the negative group index at the center of the EIT window, corresponding with the propagation of a weak light pulse from subluminal to superluminal. Moreover, the influence of the Doppler broadening effect on the group index is also included, making the results approach to actual conditions. Therefore, the suggested model may be helpful for the application realization of optical storage in quantum computers and quantum information processing.

Distal Radial Access for Coronary Procedures in a Large Prospective Multicenter Registry: The KODRA Trial

BackgroundDistal radial access (DRA) as an alternative access route lacks evidence, despite its recent reputation. ObjectivesThe aim of this study was to evaluate the safety and feasibility of DRA on the basis of daily practice. MethodsThe KODRA (Korean Prospective Registry for Evaluating the Safety and Efficacy of Distal Radial Approach) trial was a prospective multicenter registry conducted at 14 hospitals between September 2019 and September 2021. The primary endpoints were the success rates of coronary angiography (CAG) and percutaneous coronary intervention (PCI). The secondary endpoints included successful distal radial artery puncture, access-site crossover, access site–related complications, bleeding events, and predictors of puncture failure. ResultsA total of 4,977 among 5,712 screened patients were recruited after the exclusion of 735 patients. The primary endpoints, the success rates of CAG and PCI via DRA, were 100% and 98.8%, respectively, among successful punctures of the distal radial artery (94.4%). Access-site crossover occurred in 333 patients (6.7%). The rates of distal radial artery occlusion and radial artery occlusion by palpation were 0.8% (36 of 4,340) and 0.8% (33 of 4,340) at 1-month follow-up. DRA-related bleeding events were observed in 3.3% of patients, without serious hematoma. Multilevel logistic regression analysis identified weak pulse (OR: 9.994; 95% CI: 7.252-13.774) and DRA experience <100 cases (OR: 2.187; 95% CI: 1.383-3.456) as predictors of puncture failure. ConclusionsIn this large-scale prospective multicenter registry, DRA demonstrated high success rates of CAG and PCI, with a high rate of puncture success but low rates of distal radial artery occlusion, radial artery occlusion, bleeding events, and procedure-related complications. Weak pulse and DRA experience <100 cases were predictors of puncture failure. (Korean Prospective Registry for Evaluating the Safety and Efficacy of Distal Radial Approach [KODRA]; NCT04080700)

Un-diagnosed coarctation of the aorta in a 27-year-old adult with a rare presentation: a rare case report

Introduction and importance: Coarctation of the aorta (COA) is a rare form of congenital heart disease that is typically diagnosed in children. COA is known to present with hypertension, weak or absent femoral pulses, heart failure in older patients, but the presentation of COA as calf atrophy is extremely rare. This article reports the successful surgical repair of a 27-year-old adult with undiagnosed COA. Case presentation: A 27-year-old-male has presented with calf atrophy, which was diagnosed as COA transthoracic echocardiography and computed tomography angiography indicate COA, which is treated with successful surgical repair. Clinical discussion: COA is typically diagnosed in children with a rare incidence in adults. Calf atrophy is an extremely rare presentation and uncommon. He has calf atrophy, which led to the diagnosis of COA in 27 years. The presentation in this medium-aged population with this rare manifestation gives our case significance to be one of the unique reported cases. Conclusion: COA is uncommon to be found in adults and the presentation with calf atrophy is even rare. The authors revealed that COA can be found in adults and with an unexpected manifestation and highlights the significance of early detection, and timely referral to a specialist can enable proper management, which includes surgical correction.

Multi-Level Pyramidal Microstructure-Based Pressure Sensors with High Sensitivity and Wide Linear Range for Healthcare Monitoring.

Flexible pressure sensors have garnered significant attention in the field of wearable healthcare due to their scalability and shape variability. However, a crucial challenge in their practical application for various healthcare scenarios is striking a balance between the sensitivity and sensing range. This limitation arises from the reduced compressibility of the microstructures on the surface of pressure-sensitive materials under high pressure, resulting in progressive saturation of the sensor's response and leading to a restricted and nonlinear pressure sensing range. In this study, we present a novel approach utilizing multi-level pyramidal microstructures in flexible pressure sensors to achieve both high sensitivity (8775 kPa-1) and linear response (R2 = 0.997) over a wide pressure range (up to 1000 kPa). The effectiveness of the proposed design stems from the compensatory behavior of the lower pyramidal microstructures, which counteracts the declining sensitivity associated with the gradual hardening of the higher pyramidal microstructures. Furthermore, the sensor demonstrates a fast response time of 11.6 ms and a fast relaxation time of 3.8 ms and can reliably detect pressures as low as 30.2 Pa. Our findings highlight the applicability of this flexible pressure sensor in diverse human body health detection tasks, ranging from weak pulses to finger flexion and plantar pressure distribution. Notably, the proposed sensor design eliminates the need for replacing flexible pressure sensors with varying ranges, thereby enhancing their practical utility.

Study on weak sound signal separation and pattern recognition under strong background noise in marine engineering

The extraction of weak acoustic signals under strong background noise is of great significance in the applications of target identification and localization. In this paper, the pulse signal with high randomness is set as the weak signal sound source, random noise and sine sound are used as the background noise. Under the condition of a signal-to-noise ratio of −20 dB, combined with blind source separation and neural network methods, the collected observation signals are subjected to weak sound signal separation and recognition research. The optimization method of centralization and scaling processing is used to eliminate the unfavorable influence of the uncertainty of the separated signal amplitude caused by the blind source separation method on the pattern recognition. The recognition result is verified by the combination of “weak impulse acoustic signal” and “random noise signal,” and the output vector (0.99 0.01 0.01) approaches (1 0 0), which is recognized as impulse acoustic signal. By combining blind source separation and neural network methods, the separation and identification of weak pulse signals under the condition of a signal-to-noise ratio of −20 dB can be achieved.

Fiber-cavity ring-down temperature sensor using a transmissive configuration combined with the heterodyne detection technique.

A fiber Bragg grating temperature sensor based on the cavity ring-down technique is reported. A quasi-linear fiber cavity is proposed to reduce optical loss in the cavity instead of a conventional fiber-loop configuration. The heterodyne detection technique is applied to sensitively detect weak pulses from the cavity. A combination of the quasi-linear fiber cavity and heterodyne detection allows the sensitive detection of the decaying pulse trains and high-resolution measurement of the wavelength shift of the Bragg grating induced by the temperature change. A temperature resolution of about 0.01°C is achieved.

Prevalence, mortality, and aetiology of paediatric shock in a tertiary hospital in Malawi: A cohort study.

Shock is considered one of the most important mechanisms of critical illness in children. However, data on paediatric shock in sub-Saharan Africa is limited, which constrains development of effective treatment strategies. We aimed to describe the prevalence, mortality, and aetiology of paediatric shock in a tertiary hospital in Malawi. Children aged two months to 16 years presenting with shock (FEAST criteria; respiratory distress and/or impaired consciousness, and at least one sign of impaired circulation; capillary refill>3 seconds, cold extremities, weak pulse, or severe tachycardia) to the emergency department were included and followed-up prospectively using routinely collected data between February 2019 and January 2020. Prevalence, mortality and aetiology of shock were reported for both the FEAST criteria and World Health Organization (WHO) definition. The association between aetiology and mortality was assessed with univariable analysis. Of all screened admissions (N = 12,840), 679 (5.3%) children presented with shock using FEAST criteria and the mortality was 79/663 (11.9%). WHO-defined shock applied to 16/12,840 (0.1%) and the mortality was 9/15 (60.0%). Main diagnoses were viral/reactive airway diseases (40.4%), severe pneumonia (14.3%), gastroenteritis (11.3%) and presumed sepsis (5.7%). Children diagnosed with presumed sepsis and gastroenteritis had the highest odds of dying (OR 11.3; 95%-CI:4.9-25.8 and OR 4.4; 95%-CI:2.4-8.2). Considering the high mortality, prevalence of paediatric shock (FEAST and WHO definitions) in Malawi is high. Sepsis and gastroenteritis are diagnoses associated with poor outcome in these children. Consensus on a clinical meaningful definition for paediatric shock is essential to boost future studies.

Unraveling the complexity: A comprehensive guide to subclavian steal syndrome.

Subclavian steal syndrome is a diagnosis that is thought to be relatively uncommon even though its occurrence is not well understood. Some individuals may experience crippling symptoms of arm ischemia and vertebral-basilar insufficiency due to subclavian steal, which is more frequent than the accompanying illness. Patients with uneven arm blood pressure or unilaterally faint pulses should be evaluated for subclavian steal. Although it is not always necessary to check the blood pressure and pulse on both sides, they become significant when these measurements differ and are accompanied by vertebral-basilar or arm ischemia symptoms. Although subclavian steal does not significantly increase the risk of stroke, it is nevertheless essential to recognize and treat asymmetric blood pressure and weak pulses as these may be signs of subclavian steal syndrome. This page thoroughly analyses the aetiology of subclavian steal syndrome, signs, symptoms, diagnosis, and available treatments.

Fast switching between the ground- and excited-state lasing in a quantum-dot microdisk triggered by sub-ps pulses.

A quantum-dot microdisk was optically pumped by continuous-wave excitation with a level sufficient for the ground-state lasing. The microdisk was additionally illuminated with sub-ps pulses of various powers. It was found that there is a critical level of pulse power that determines the subsequent transient process of the microlaser. Depending on the level of the pulsed excitation, the ground-state lasing intensity can be either enhanced (for weak pulses) or fully quenched (for strong pulses). In the latter case, the excited-state lasing is ignited for a short time. All dynamic phenomena occur on a time scale of the order of 100 ps, and the duration of the transient process as a whole (from the arrival of the excitation pulse to the restoration of steady-state intensities) lasts no more than 0.5 ns. Using this phenomenon, a microlaser can be rapidly switched between two states with the switching controlled by the level of the incoming optical pulse.

Spontaneous hydropneumothorax with unknown origin and new onset hyperosmolar hyperglycemic state: case report in limited health facility

Introduction: Hydropneumothorax and Hyperosmolar Hyperglycaemic State (HHS) are uncommon disorders with serious mortality. Both conditions need appropriate intervention and monitoring in comprehensive health facilities. Reports on the occurrence of spontaneous hydropneumothorax accompanied by HHS are still limited, due to the rarity of these two disorders.Case Presentation: A 42-year-old woman with abrupt shortness of breath started 1 day ago. No coughing or chest pain. Losing weight in last six months. There was no history of any disease and medication. Physical findings were drowsy consciousness with tachycardia and weak pulse, asymmetrical chest expansion with retraction, vesicular breath sounds diminished in the left lung following hyper resonant in percussion. The extremities were cold and dry. Skin turgor was reduced. Plain CXR revealed air and fluid in left pleural cavity. Laboratory test revealed very high blood glucose with hyperosmolarity.Discussion: Hydropneumothorax is the presence of air in the pleural space accompanied by ipsilateral effusion. The manifestations include shortness of breath, increased work of breathing, and sharp chest pain, or asymptomatic. It is unclear whether this patient's hyperglycaemia is related to the occurrence of spontaneous hydropneumothorax. HHS can be diagnosed by effective serum osmolality with glucose levels plus appropriate medical presentation. The management is based on the correction of dehydration, hyperglycaemia, hyperosmolarity, and precipitating conditions.Conclusion: Both hydropneumothorax and HHS have high mortality rates, particularly when the two conditions coexist. This case met some challenging issues that might increase the mortality.

The identification of WHO emergency signs in children by nurses at triage in an emergency department

ABSTRACT Background The World Health Organization recommends the use of a three-tier triage system to recognise a sick child in low- and middle-income countries. The three tiers are based on standardised emergency and priority signs. No studies have evaluated the prevalence or reliable detection of these emergency signs. Aims To determine the prevalence of WHO emergency signs and the underlying causes, and to determine whether nurses could reliably detect these signs in children presenting to the emergency department at Port Moresby General Hospital in Papua New Guinea. Methods A prospective study measured inter-rater agreement between nurses at triage and a blinded second assessor trained in paediatrics. Results The prevalence of emergency signs was 16.7%: 32 of 192 children had these signs at presentation; 18 (9.4%) had severe respiratory distress; 10 (5.2%) had severe dehydration; and 3 (1.6%) had convulsions. There was an acceptable inter-rater agreement between nurses and doctors (Cohen’s Kappa score >0.4) for some signs: subcostal recession, intercostal recession, nasal flaring, lethargy, weak volume pulses, convulsions, sunken eyes and a poor conscious state. Obstructed breathing, cyanosis, tracheal tug and cold hands and feet were less commonly detected and had poor inter-rater agreement (Kappa score <0.4). Conclusions Effective screening at triage can enable prompt emergency treatment by nurses and can help focus doctors’ attention on children who require it most. There is a need for additional training in the identification of some emergency signs. Abbreviations CED: children’s emergency department; ETAT: emergency triage assessment and treatment; HCC: Hospital Care for Children; PMGH: Port Moresby General Hospital; PNG: Papua New Guinea; WHO: World Health Organization

Intoxicação por amitraz em um gato

ABSTRACT: A 4-month-old male Himalayan cat presented with clinical signs of acute lethargy and motor incoordination after being treated with amitraz for parasite control. On clinical examination, the patient was lethargic and ataxic with severe pulicosis, hypothermia, pale mucous membranes, bradycardia, weak femoral pulses, hyperglycemia, and bilateral mydriasis. Blood tests revealed non-regenerative hypochromic microcytic anemia. Serum alanine levels were elevated tenfold. The patient received supportive treatment with atipamezole (an α2-adrenergic antagonist) at a dose of 0.1 mg/kg intramuscularly. After 24 h of hospitalization and constant monitoring, the patient recovered and was discharged. The published literature showed that the active ingredient amitraz is effective in the treatment of some parasitic diseases in cats, such as scabies and demodicosis; therefore, it is still used for this purpose. Given the small therapeutic margin of this insecticide, veterinarians should caution owners about its potential toxicity. This report emphasized the significance of amitraz intoxication in feline species and the success of the treatment, which should be initiated in the first hour after intoxication.

Buerger's Disease of Hand; my Experience with Phenol Chemical Neurolysis of Stellate Ganglion: Case Series of Six Patients.

Buerger's disease is common in 74.70% of cases in the lower limb but in 20.20% of cases, it is found in the upper limb or hand. The disease usually starts from pain in the finger/thumb or hand and then to more centrally.Patients presented with pain in the hand with gangrene of fingers. Pain aggravated on lifting hand above the shoulder level or above heart level in upright or lying in the bed, respectively. In almost all patients, there was a history of smoking except one and all patients had involvement of digits of the right or left hand. Diagnosis of Buerger's disease was made based on the history of smoking, weak or absent pulse, lack of bleeding, swelling, edema, blackening, stony hard fingers or thumb on clinical examination, and color Doppler study of the limb.In all patients, Stellate ganglion chemical neurolysis with 8% phenol was done at C7-T1 under fluoroscopic and radiocontrast dye (Iohexol 300) guidance.After successful neurolysis patients got excellent pain relief, their wounds started healing, the vascularity of the diseased part increased and the disease stopped progressing. Stellate ganglion chemical neurolysis with phenol in Peripheral vascular disease or Buerger's disease of hand is an effective method to stop the disease procession, promoting wound healing, controlling ischemic pain, and avoiding surgical amputation.