Pulse compression (PC) active sonar waveforms provide a significant improvement in range resolution over single-frequency sinusoidal waveforms also known as continuous wave (CW) waveforms. Since ...their inception in the 1940s, a wide variety of PC waveforms have been designed using either frequency modulation (FM), phase coding, or frequency hopping to suite particular sonar applications. The sinusoidal FM (SFM) waveform modulates its instantaneous frequency (IF) by a sinusoid to achieve high Doppler sensitivity which also aids in suppressing reverberation. This allows the SFM waveform to resolve target velocities. While the SFM's resolution in range is inversely proportional to its bandwidth, the SFM's autocorrelation function (ACF) contains many large sidelobes. The periodicity of the SFM's IF creates these sidelobes and impairs the SFM's ability to clearly distinguish multiple targets in range. This paper describes a generalization of the SFM waveform, referred to as the generalized SFM (GSFM) waveform, which modifies the SFM's IF to resemble the time/voltage characteristic of an FM chirp waveform. As a result of this modification, the Doppler sensitivity of the SFM is preserved while substantially reducing the high range sidelobes, producing a waveform whose ambiguity function (AF) approaches a thumbtack shape. This paper focuses primarily on the properties of the GSFM's thumbtack AF shape and compares it to other well-known waveforms with a similar AF shape. The GSFM waveform achieves zero range-Doppler coupling for single target measurements which in turn minimizes the variance in jointly estimating target range and velocity and optimizes resolution of multiple point targets in range and velocity. The GSFM's AF peak sidelobe levels, which determine the waveform's ability to detect weak targets in the presence of strong ones, are comparable to other well-established thumbtack AF waveforms such as Costas or phase-coded waveforms over a wide range of time-bandwidth product (TBP) values.
A magnetohydrodynamic (MHD) fluid description is typically employed to study the magnetized plasma comprising the solar atmosphere. This approach has had many successes in modeling and explaining ...solar phenomena. Most often, the plasma is assumed to be fully ionized. While this approach is justified in the higher atmosphere, i.e., the solar corona; the temperature in the lower solar atmosphere is such that a large proportion of the fluid may be electrically neutral. This begs the question: to what degree are the results derived from a fully ionized MHD description valid? In this article, we investigate the effect of partial ionization on buoyancy-driven MHD waves (the MHD analog of internal gravity waves) by applying a simplified two-fluid description. We show that previously derived results may be applied, when the fluid is weakly ionized, if the ion-neutral collision frequency is high. We derive dispersion relations for buoyancy-driven MHD waves, which include correction factors and damping rates due to ion-neutral collisions.
Abstract
Background
Tendon and ligament injuries are significant causes of loss of use and early retirement in performance horses. Amniotic fluid and tissue are excellent sources of growth factors ...and cytokines important in tendon and ligament healing. Thus, an equine-origin liquid amnion allograft (ELAA) may be beneficial in the treatment of equine tendonitis and desmitis. Objectives of this study were to report the outcome achieved (i.e. ability to return to work) for horses diagnosed with tendonitis or desmitis lesions treated with local injection of ELAA and to compare these outcomes to those reported for other regenerative medicine modalities.
Methods
A prospective, multi-center, non-blinded clinical trial was conducted. Equine veterinarians at 14 sites were selected to participate in the data collection for the trial. Criterion for inclusion was a horse presenting with lameness which was attributed to tendonitis or desmitis by diagnostic anesthesia and/or imaging. These horses were subsequently treated by local injection of the lesion with ELAA by the attending veterinarian. Standardized questionnaires describing each horse’s signalment, discipline, ability to return to work, and any adverse events were completed and submitted by the attending veterinarian following a minimum of six months of follow-up. The current literature was reviewed to identify clinical studies reporting outcomes of equine tendonitis/desmitis lesions treated with other regenerative therapies. Contingency table analyses were performed comparing outcomes.
Results
Questionnaires for 100 horses with 128 tendonitis and desmitis lesions met the inclusion criteria. Of these, 72 horses with 94 lesions returned to or exceeded their original level of work, 10 horses with 13 lesions returned to work but could not perform to previous standards, and 18 horses with 20 lesions did not return to work as a result of the injury. No differences were observed when outcome of horses treated with ELAA were compared to those of similar studies using other regenerative therapies.
Conclusions
Treatment of tendonitis and desmitis lesions by local injection of ELAA resulted in similar outcomes for horses returning to previous level of performance as other regenerative modalities such as mesenchymal stem cells, platelet-rich plasma, and autologous conditioned serum; however, blinded placebo-controlled studies are indicated.
ABSTRACT Turbulent motions close to the visible solar surface may generate low-frequency internal gravity waves (IGWs) that propagate through the lower solar atmosphere. Magnetic activity is ...ubiquitous throughout the solar atmosphere, so it is expected that the behavior of IGWs is to be affected. In this article we investigate the role of an equilibrium magnetic field on propagating and standing buoyancy oscillations in a gravitationally stratified medium. We assume that this background magnetic field is parallel to the direction of gravitational stratification. It is known that when the equilibrium magnetic field is weak and the background is isothermal, the frequencies of standing IGWs are sensitive to the presence of magnetism. Here, we generalize this result to the case of a slowly varying temperature. To do this, we make use of the Boussinesq approximation. A comparison between the hydrodynamic and magnetohydrodynamic cases allows us to deduce the effects due to a magnetic field. It is shown that the frequency of IGWs may depart significantly from the Brunt-Väisälä frequency, even for a weak magnetic field. The mathematical techniques applied here give a clearer picture of the wave mode identification, which has previously been misinterpreted. An observational test is urged to validate the theoretical findings.
This article presents an adaptive waveform design method using multitone sinusoidal frequency modulation (MTSFM). The MTSFM waveform's modulation function is represented as a finite Fourier series ...expansion. The Fourier coefficients are utilized as a discrete set of design parameters. These design parameters can be modified to shape the spectrum, auto-correlation function (ACF), and ambiguity function (AF) shapes of the waveform. The MTSFM waveform model naturally possesses the constant envelope and spectral compactness properties that make it well suited for transmission on practical radar/sonar transmitters which utilize high power amplifiers. The MTSFM has an exact mathematical definition for its time-series using generalized Bessel functions which allow for deriving closed-form analytical expressions for its spectrum, AF, and ACF. These expressions allow for establishing well-defined optimization problems that finely tune the MTSFM's properties. This adaptive waveform design model is demonstrated by optimizing MTSFM waveforms that initially possess a "thumbtack-like" AF shape. The resulting optimized designs possess substantially improved sidelobe levels over specified regions in the range-Doppler plane without increasing their time-bandwidth product. Simulations additionally demonstrate that the optimized thumbtacklike MTSFM waveforms are competitive with thumbtacklike phase-coded waveforms derived from design algorithms available in the published literature.
The COVID-19 pandemic necessitated a change in our practice in the management of pediatric soft-tissue injuries. Patients were managed conservatively whenever possible. Our aim in this study was to ...see whether this more conservative approach adversely affected clinical, and patient-reported outcomes, including scarring. A prospective record of children presenting to the plastic surgery “Early Bird” clinic for pediatric trauma between 01.04.2020 and 30.06.2020 was kept. Electronic patient records were reviewed. An outpatient telephone clinic was scheduled for all patients. Parents were asked about complications and what they thought about the scar and to rate it as either: “poor,” “satisfactory,” “good,” or “excellent.” There were 240 patients, including 136 (57%) males and 104 (43%) females. The most frequent type of injury was a facial laceration in 123 patients (51.3%), followed by hand lacerations in 43 (17.9%), fingertip injuries in 31 (12.9%), and others. Ninety out of 240 (37.5%) were offered surgery. Follow-up times ranged from 17 to 20 months. Most parents (86.2%) were happy with the scarring and reported it as “good” or “excellent.” The proportion rating the scar “excellent” or “good” was similar in the non-operated cohort (i.e., 85.5%) versus the operated cohort (88.5%) (p-value 0.16). The overall complication rate of patients seen during this time was 5.9%; 7.4% in the conservatively managed and 4.9% of those who went to the theater. Despite managing more wounds, including some dog bites, conservatively, patients and parents reported low complication rates and high levels of satisfaction with the final scarring.
There is increasing recognition of the wicked nature of the intertwined climate, biodiversity and economic crises, and the need for adaptive, multi-scale approaches to understanding the complexity of ...both the problems and potential responses. Most science underpinning policy responses to sustainability issues, however, remains overtly apolitical and focussed on technical innovation; at odds with a critical body of literatures insisting on the recognition of systemic problem framing when supporting policy processes. This paper documents the experience of implementing a mixed method approach called quantitative story-telling (QST) to policy analysis that explicitly recognises this normative dimension, as the methodology is part of a post-normal science (PNS) toolkit. The authors reflect on what was learnt when considering how QST fared as a tool for science–policy interaction, working with European Union (EU) level policy actors interested in sustainable agriculture and sustainable development goal 2. These goals—also known as UN Agenda 2030—are the latest institutionalisation of the pursuit of sustainable development and the EU has positioned itself as taking a lead in its implementation. Thus, the paper illustrates our experience of using PNS as an approach to science policy interfaces in a strategic policy context; and illustrates how the challenges identified in the science–policy literature are amplified when working across multiple policy domains and taking a complex systems approach. Our discussion on lessons learnt may be of interest to researchers seeking to work with policy-makers on complex sustainability issues.
As colorectal cancer remains the second highest cause of cancer-related deaths in much of the industrialised world, identifying novel strategies to prevent colorectal tumour development remains an ...important challenge. BAG-1 is a multi-functional protein, the expression of which is up-regulated at relatively early stages in colorectal tumorigenesis. Importantly, BAG-1 is thought to enhance colorectal tumour progression through promoting tumour cell survival. Here, we report for the first time a novel role for BAG-1, establishing it as a suppressor of transforming growth factor β (TGF-β1) expression in colorectal tumour cells. Microarray analysis first highlighted the possibility that BAG-1 may regulate TGF-β1 expression, a key cytokine in normal colonic tissue homoeostasis. Q-RT-PCR and ELISA demonstrated TGFB1 mRNA and protein expression to be significantly increased when BAG1 levels were reduced by small interfering RNA; additionally, induction of BAG-1L caused suppression of TGFB1 mRNA in colorectal tumour cells. Using reporter and chromatin immunoprecipitation assays, a direct association of BAG-1 with the TGFB1 gene regulatory region was identified. Immunohistochemistry and Weiser fraction data indicated that the levels of BAG-1 and TGF-β1 are inversely correlated in the normal colonic epithelium in vivo, consistent with a role for BAG-1-mediated repression of TGF-β1 production. In vitro studies showed that the change in TGF-β1 production following manipulation of BAG-1 is functionally relevant; through induction of anchorage-independent growth in TGF-β1-dependent normal rat kidney fibroblasts and regulation of SMAD2 phosphorylation in TGF-β1-sensitive adenoma cells. Taken together, this study identifies the anti-apoptotic protein BAG-1 as a suppressor of the inhibitory growth factor TGF-β1, suggesting that high expression of BAG-1 can impact on a number of the hallmarks of cancer, of potential importance in promoting the early stages of colorectal tumorigenesis. Establishing BAG-1 as a repressor of TGF-β1 has important biological implications, and highlights a new role for BAG-1 in colorectal tumorigenesis.
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