Deep Attenuation Research Articles

Insights from ScS–S measurements on deep mantle attenuation

We apply a recently developed method based on the instantaneous frequency to analyze broadband seismic data recorded by the transportable USArray. We measure in the frequency band [0.018–0.2]Hz about 700 high-quality differential ScS–S anelastic delay times, δtScS–S⋆, sampling the mantle below Central America and below Alaska that we compare to elastic delay times, δtScS–S, obtained by cross-correlating the S and ScS signals. We confirm that the instantaneous frequency matching method is more robust than the classical spectral ratio method. By a series of careful analyses of the effects of signal-to-noise ratio, source mechanism characteristics and possible phase interferences on measurements of differential anelastic delay times, we demonstrate that in order to obtain accurate values of δtScS–S⁎ the seismic records must be rigorously selected. In spite of the limited number of data that satisfy our quality criteria, we recover, using an additional stacking procedure, a clear dependence of δtScS–S⋆ on the epicentral distance in the two regions. The absence of correlation between the obtained anelastic and elastic delay-times indicates a complex compositional-thermal origin of the attenuation structure, or effects of scattering by small scale structure, in accordance with possible presence of subducted material. The regional 1-D inversions of our measurements indicate a non-uniform lower mantle attenuation structure: a zone with high attenuation in the mid-lower mantle (Qμ≈250) and a low attenuation layer at its base (Qμ≈450). A comparison of our results with low-frequency normal-model Q models is consistent with frequency-dependent attenuation with Qμ∝ωα and α=0.1–0.2 (i.e. less attenuation at higher frequencies), although possible effects of lateral variations in Q in the deep mantle add some uncertainty to these values.

Изменения характеристик парадоксального сна – ранний признак болезни Паркинсона

Data on the sleep disorders in patients with Parkinson's disease are given. The basic point focuses on analysis of paradoxical sleep without muscle atonia. The author reports developed models of preclinical and clinical stages of Parkinson's disease in Wistar rats on the basis ofa moderate and deep attenuation in activity of ubiquitin-proteasome system, a key mechanism of aging and development of conformation disease. The hypothesis about changes in the characteristics of paradoxical sleep as a marker of parkinsonism stages is validated. It reflects the state of compensator and neuroprotective reserves of nigrostriatal dophaminergic system.

Benign Teratoma of the Thyroid Gland

Although pathology reports of thyroid tissue in ovarian teratomas are abundant, benign teratomas of the thyroid are extremely rare in adolescents and adults. Therefore, their clinical characteristics are still not well characterized. We report a case of a 54-year-old woman with a growing mass in her neck. Left lobectomy of the thyroid revealed it to be a benign thyroid teratoma composed of tissues from all three germ layers. Preoperative evaluations included thyroid ultrasonography (US), ultrasound-guided fine needle aspiration cytology (FNAC), and computed tomography (CT) of the neck. A 4.7-cm, well defined, predominantly hypoechoic mass intermingled with hyperechoic internal lesions, was observed in the inferior portion of the left thyroid lobe with substernal extension on US. The posterior extent of the nodule was not visualized due to deep attenuation of the echo. US-guided FNAC failed to reveal any thyroid follicular cells, but suggested a benign cystic tumor. Neck CT hinted at the diagnosis of teratoma because the mass contained large amounts of fat, and the margin was well defined. Extrathyroidal extension and cervical lymphadenopathy were not seen. She underwent left thyroid lobectomy, and histologic examination confirmed benign thyroid teratoma. To the best of our knowledge, this is the first case report of benign thyroid teratoma in Korea.

Analysis and Design of Low Pass Filter using Unit Cell based on CRLH Transmission Line

In this paper, a unit cell for low pass filter design by using composite right and left-handed transmission line in conductor-backed coplanar waveguide is proposed. The characteristics of the unit cell are analyzed in order to design a low pass filter in small sizes. By changing the sizes of the unit cell, the parameters of right-handed and left-handed immittance components are changed and the desired characteristics of the unit cell are achieved. The equivalent circuit of the unit cell is extracted and analyzed either. As a result, the simulation results of the unit cell and the equivalent circuit are almost identified. The movement and energy distributions of electromagnetic field are shown to confirm the property of the unit cell. In the end, a low pass filter is demonstrated by cascading three proposed unit cells, which shows cutoff frequency of 1.53GHz and deep attenuation from 2.23GHz to 4.49GHz lower than -50dB.

Importance of the liver ultrasound scores in pubertal obese children with nonalcoholic fatty liver disease

AimThe purpose of our study was to determine the relationship between liver ultrasound scores and insulin sensitivity in a population of obese children with nonalcoholic fatty liver disease (NAFLD) and the relationships between other metabolic features and ultrasound scores. MethodsOne hundred sixty-nine obese adolescents, 96 girls, and 73 boys (mean age: 12.7±1.3 years, mean body mass index: 26.3±4.6) were enrolled the study. The obese subjects were divided into 2 groups based on their pubertal status. Ultrasonography findings were scored in this study included hepatorenal echo contrast, liver brightness, deep attenuation, and vascular blurring. Scores ranged from 0 to 6 points, and NAFLD was defined if ultrasound score was ≥1. Insulin resistance was evaluated by homeostasis model assessment (HOMA-IR) from fasting samples. ResultsPrevalence of NAFLD in pubertal children (61.9%) had significantly higher than pre-pubertal children (40.8%) (P=.008). Transaminases ratio was significantly correlated in both prepubertal (r=0.231; P=.03) and pubertal (r=0.628, P=0.017) groups. HOMA-IR values were elevated in both groups; however, liver ultrasound score was positively correlated with HOMA-IR (r=0.735, P=.014) in pubertal children. ConclusionNAFLD prevalence among obese children is quite high, especially pubertal adolescents than prepubertal children. We demonstrated an association between insulin resistance and NAFLD ultrasound scoring in pubertal obese children. We suggested that ultrasound examination of the liver be included in the routine check-up of the pubertal obese children with insulin resistance to allow the detection of NAFLD at an early stage.

Evaluation of the correlation between serum biochemical values and liver ultrasonographic indices in periparturient cows with different body condition scores

To determine alterations of serum biochemical variables in relation to changes of near- and far-field mean grayscale histogram (MGSH) and attenuation rates in liver ultrasonograms of periparturient cows. 67 Holstein cows. Cows were allocated on the basis of body condition score into underconditioned (n = 21), moderately conditioned (23), and overconditioned (23) groups. Serum samples (obtained every 10 days from 30 days before to 30 days after calving) were analyzed for aspartate aminotransferase, alanine aminotransferase, and γ-glutamyltransferase activities and BUN, albumin, calcium, and inorganic phosphorus concentrations along with digital estimation of near- and far-field MGSH values of liver ultrasonograms and deep attenuation. Values were compared among groups and within each group, and their correlations were determined in the pre- and postpartum periods. Serum biochemical variables did not differ significantly among groups. Aspartate aminotransferase and γ-glutamyltransferase activities increased in the postpartum period. Fluctuations of alanine aminotransferase activity were not significant; BUN decreased significantly in the peripartum period. Albumin concentration decreased prior to parturition and remained low, but significantly increased after parturition. Calcium concentration decreased on day 10 but subsequently increased. Phosphorus concentration decreased stepwise until day 10 after calving. Postpartum biochemical variables had weak correlations with near- and far-field MGSH values in overconditioned cows. The highest levels of sound attenuation were found in overconditioned cows on calving day. Liver ultrasonographic features were poorly correlated with changes of serum biochemical variables. This suggests that liver ultrasonography is not a good technique for estimating functional liver abnormalities in periparturient cows.

Deep Echo Attenuation without Calcification Increases the Risk of Periprocedural Myonecrosis after Elective Percutaneous Coronary Intervention in Patients with Coronary Artery Disease

To investigate the clinical factors, including intravascular ultrasound (IVUS) findings, associated with percutaneous coronary intervention (PCI)-related periprocedural myonecrosis (PM) in patients with stable coronary artery disease (CAD). The study included 46 patients (mean age 65±2 y, 37 men) with stable CAD who underwent elective PCI using IVUS and a Doppler flow guidewire. In addition to routine IVUS measurements, the presence of deep echo attenuation (DEA) without calcification was assessed. The sum of all high-intensity transient signals (HITS) after a balloon deflation procedure was calculated using a Doppler flow guidewire. PM was defined as an elevation in troponin T to >0.03 ng/mL 24-hour after PCI. Patients were divided into 2 groups on the basis of the presence or absence of PM. PM was identified in 17 patients (37%). Estimated glomerular filtration ratio was lower in the PM group (p=0.021). Target vessel distribution was different between the groups (p=0.004). Positive remodeling and DEA, as observed on IVUS, were more common in the PM group (p=0.03 and p<0.0001, respectively). The total number of HITS was higher in the PM group (p=0.003). Logistic regression analysis demonstrated that the presence of DEA (p=0.003) was the sole factor associated with the occurrence of PM. These results demonstrated that DEA is an important factor associated with PM in patients who underwent an elective PCI. Therefore, IVUS to determine the presence of DEA should be performed before PCI.

Abstract 17839: Attenuated Plaque: Novel IVUS Predictors of No-reflow in the Percutaneous Coronary Intervention of Thrombus-Containing Lesions

We investigated the relationship between no-reflow and pre-intervention intravascular ultrasound (IVUS) findings in 87 patients with angiographic evidence of target lesion thrombus (defined as presence of generalized haziness or filling defect) within native arteries undergoing percutaneous coronary intervention (PCI) without a distal protection device. Angiographic no-reflow was defined as post-PCI TIMI flow grade 0∼2. IVUS assessment included (1) morphological characteristics of thrombus (scintillating appearance, lobulated mass, distinct interface between the suspect thrombi and plaque, or microchannels within a lobulated mass), (2) thrombus mobility, and (3) presence of attenuated plaque (plaque with deep echo attenuation, but without calcification). Results: There were no serious IVUS-imaging related procedural complications. IVUS identified thrombus in 59 lesions (67.8%): scintillation in 39.1%, lobulated mass in 56.3%, distinct interface in 10.3%, microchannels in 9.2%, mobility in 24.1%, and attenuated plaque in 41.4%. Most attenuated plaques (88.9%) were detected at the minimal lumen area site. No-reflow was observed in 21 lesions post-PCI (24.1%). In general, IVUS features of thrombus were significantly more common in lesions that developed no-reflow; however, multivariate logistic regression analysis showed that attenuated plaque (p=0.012; OR, 6.04; 95% CI, 2.33∼15.70) and thrombus mobility (p&lt;0.0001; OR, 31.33; 95% CI, 6.54∼149.93) were independent predictors of post-PCI no-reflow in angiographic thrombus-containing lesion. Conclusions: IVUS imaging of angiographic thrombus-containing target lesions is safe. In thrombus-containing native coronary artery lesions IVUS findings of mobility and attenuated plaque predict no-reflow; and the use of distal protection should be considered.

A novel X-band broadband bandstop filter with sharp cut-off frequency using EBG dual-ear structures

A novel X-band broadband bandstop filter (BSF) with sharp cut off frequency is presented, using novel design of periodic electromagnetic bandgap (EBG) dual-ear (DE) structures on coplanar waveguide (CPW) transmission line. An equivalent lumped circuit is introduced to model the BSF with EBG-DE structures. The stopband of this filter is ranged within X-band to have sharp selectivity and deep attenuation levels. The 3-dB bandwidth of the BSF is 4.2 GHz, from 8.6 to 12.8 GHz and the center frequency is 11.5 GHz. The 20-dB bandwidth is 2 GHz, from 9.9 to 11.9 GHz. In 20-dB stop-band range, the ripple of return loss is less than 0.05 dB.The proposal BSF is fabricated using the surface micromachining, and the measurement and simulation results coincided well. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26031

Optical Coherence Tomography Analysis of Attenuated Plaques Detected by Intravascular Ultrasound in Patients with Acute Coronary Syndromes

Background. Recent intravascular ultrasound (IVUS) studies have demonstrated that hypoechoic plaque with deep ultrasound attenuation despite absence of bright calcium is common in acute coronary syndrome. Such “attenuated plaque” may be an IVUS characteristic of unstable lesion. Methods. We used optical coherence tomography (OCT) in 104 patients with unstable angina to compare lesion characteristics between IVUS-detected attenuated plaque and nonattenuated plaque. Results. IVUS-detected attenuated plaque was observed in 41 (39%) patients. OCT-detected lipidic plaque (88% versus 49%, P < 0.001), thin-cap fibroatheroma (48% versus 16%, P < 0.001), plaque rupture (44% versus 11%, P < 0.001), and intracoronary thrombus (54% versus 17%, P < 0.001) were more often seen in IVUS-detected attenuated plaques compared with nonattenuated plaques. Conclusions. IVUS-detected attenuated plaque has many characteristics of unstable coronary lesion. The presence of attended plaque might be an important marker of lesion instability.

Characterization of subsurface polycyclic aromatic hydrocarbons at the Deepwater Horizon site

Here, we report the initial observations of distributions of polycyclic aromatic hydrocarbons (PAH) in subsurface waters near the Deepwater Horizon oil well site (also referred to as the Macondo, Mississippi Canyon Block 252 or MC252 well). Profiles of in situ fluorescence and beam attenuation conducted during 9‐16 May 2010 were characterized by distinct peaks at depths greater than 1000 m, with highest intensities close to the wellhead and decreasing intensities with increasing distance from the wellhead. Gas chromatography/mass spectrometry (GC/MS) analyses of water samples coinciding with the deep fluorescence and beam attenuation anomalies confirmed the presence of polycyclic aromatic hydrocarbons (PAH) at concentrations reaching 189 μg L−1 (ppb). Subsurface exposure to PAH at levels considered to be toxic to marine organisms would have occurred in discrete depth layers between 1000 and 1400 m in the region southwest of the wellhead site and extending at least as far as 13 km.

Quasi-elliptic filter characteristics of an asymmetric defected ground structure

An asymmetric defected ground structure (DGS) with respect to a microstrip line is proposed. Its unit cell consists of two square slots connected with a rectangular slot by meandered transverse slots. The simulated, measured and equivalent circuit responses have been presented. The unit DGS pattern under microstrip line produces wide rejection bandwidth and high sharpness factor. Its elliptic band-reject filter response is modelled by appropriate LC equivalent circuit. Two such DGS cells under a microstrip line produce 3-pole quasi-elliptic bandstop filter response, which shows deeper attenuation without appreciable change in pole frequencies in comparison to single cell structure. Unit DGS pattern under coupled gap microstrip lines produces band-accept filtering characteristics. The frequency characteristics show a quasi-elliptic highpass filtering characteristics with sharp lower transition knee. Accordingly, an LC equivalent circuit is proposed. A cascaded band-accept and band-reject filter is proposed for designing a wideband bandpass filter. The bandwidth and centre frequency of the bandpass filter can be varied by choosing different set of DGS dimensions.

Attenuated Plaque at Nonculprit Lesions in Patients Enrolled in Intravascular Ultrasound Atherosclerosis Progression Trials

We investigated attenuated plaque (hypoechoic plaque with deep ultrasonic attenuation despite absence of bright calcium) in nonculprit lesions. Recent intravascular ultrasound (IVUS) studies describe acoustic shadowing behind large, echolucent, acute culprit lesion sites in the absence of bright calcium. Such "attenuated plaque" is considered a characteristic of high-risk lesions, but its prevalence in stable nonculprit lesions is incompletely known. We reviewed IVUS pullback data from nonculprit vessels in 159 patients from the ASTEROID (A Study to Evaluate the Effect of Rosuvastatin on Intravascular Ultrasound-Derived Coronary Atheroma Burden) trial. We identified attenuated plaque and compared volumetric IVUS data in the segments with and without attenuation. In addition, we described plaque morphology in segments with attenuation at baseline and follow-up. Attenuated plaque was found in 17 of 159 patients (10.7%, 95% confidence interval: 6% to 17%). At baseline, there were no significant differences in clinical presentation and cardiovascular risk factors between patients with and without attenuation. Other than a greater plaque eccentricity index (p = 0.008), there were no significant differences between segments with and without attenuation. In segments with attenuated plaque, expansive remodeling was observed in 53%, and calcified plaque adjacent to the attenuation site in 70% of patients. During follow-up, attenuation remained stable, and no events occurred in the patients with attenuation. Attenuated plaque is present in a significant number of nonculprit segments in patients enrolled in IVUS progression trials and remains stable during follow-up. There is a relationship with mixed calcified lesions. These findings challenge the prior assumption that attenuated plaque is a finding limited to culprit lesions associated with acute clinical presentation.

Design of seven‐pole LPF with high suppression of harmonics using DGS

AbstractThe LPF is designed with defected ground structure (DGS) and broadened transmission line elements with very low impedance. A seven pole DGS‐LPF for GSM applications is found to gives deeper attenuation than provided by the previous published work. The length of DGS‐LPF is reduced to 41.5% compared with conventional LPF. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 760–763, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24155

Attenuated Plaque Detected by Intravascular Ultrasound: Clinical, Angiographic, and Morphologic Features and Post-Percutaneous Coronary Intervention Complications in Patients With Acute Coronary Syndromes

We evaluated the clinical significance of attenuated plaque (hypoechoic plaque with deep ultrasound attenuation). Attenuated plaques are unusual intravascular ultrasound (IVUS) findings in patients with acute coronary syndrome (ACS). We reviewed clinical presentations and angiographic and pre-intervention IVUS findings in 293 ACS patients undergoing percutaneous coronary intervention (PCI) without a distal protection device: 187 with non-ST-segment elevation myocardial infarction (NSTEMI) and 106 with ST-segment elevation myocardial infarction (STEMI). Attenuated plaque was observed in 75 patients (25.6%): 39.6% of STEMI versus 17.6% of NSTEMI (p < 0.001). (We also reviewed 100 randomly selected patients with stable angina and pre-intervention IVUS; none had attenuated plaque.) Overall, in ACS patients with attenuated plaques: 1) the level of C-reactive protein was higher; 2) angiographic thrombus and initial coronary flow Thrombolysis In Myocardial Infarction flow grade <2 were more common; and 3) IVUS lesion site plaque burden and remodeling index were significantly greater, lesion site luminal dimensions significantly smaller, and thrombus, positive remodeling, and plaque rupture were more common. No-reflow (26.7% vs. 4.6%, p < 0.001) and deteriorated post-PCI coronary blood flow (8.0% vs. 2.8%, p = 0.001) were higher. In ACS patients with normal coronary blood flow at baseline, deterioration in the coronary blood flow post-PCI was more common in lesions with attenuated plaque. Attenuated plaque was more common in ACS patients with STEMI than NSTEMI. Attenuated plaque in ACS patients was associated with a higher C-reactive protein level, more severe and complex lesion morphology, reduced coronary blood flow before PCI, and especially no-reflow after PCI.

Controlling Tremor with Adenosine

Deep brain stimulation (DBS), in which high-frequency electrical stimuli are continuously delivered into the brain through implanted wires, is an effective treatment for movement disorders characterized by muscle tremors, including Parkinson’s disease and essential tremor (see Asaad and Eskandar). Bekar et al . provide evidence that one mechanism by which DBS reduces tremor is through stimulation of nonsynaptic release of adenosine triphosphate (ATP). Conversion of ATP to adenosine by ectoATPases then stimulates the activation of A1 receptors. The authors detected ATP in thalamic slices (and exposed mouse cortex) in response to high-frequency stimulation with a bioluminescence assay. Adenosine was detected in the thalamic slices with an amperometric biosensor, and production by ectoATPases was confirmed by pharmacological inhibition. The release of ATP was deemed to be nonsynaptic, because it did not require calcium and removal of extracellular calcium increased the accumulation of adenosine in response to high-frequency stimulation. The role of the A1 receptor and adenosine was also confirmed by showing that high-frequency stimulation failed to reduce evoked excitatory postsynaptic potentials (eEPSPs) in the presence of an A1 receptor antagonist or an inhibitor of ectoATPase activity. Application of adenosine or an A1 receptor agonist reduced eEPSP amplitude in the absence of high-frequency stimulation. In slices from mice deficient for A1 receptors, high-frequency stimulation failed to reduce eEPSP amplitude. Using a mouse model of essential tremor, the authors showed that administration of an A1 receptor antagonist exacerbated the tremor; delivery of adenosine or an A1 receptor agonist reduced the tremor, as did DBS. As DBS is also under investigation for application in other neurological disorders, such as obsessive-compulsive disorder and depression, understanding the mechanisms by which it exerts its effects may allow for more precise treatments that limit undesirable side effects. L. Bekar, W. Libionka, G.-F. Tian, Q. Xu, A. Torres, X. Wang, D. Lovatt, E. Williams, T. Takano, J. Schnermann, R. Bakos, M. Nedergaard, Adenosine is crucial for deep brain stimulation-mediated attenuation of tremor. Nat. Med. 14 , 75-80 (2008). [PubMed] W. Asaad, E. Eskandar, The movers and shakers of deep brain stimulation. Nat. Med. 14 , 17-19 (2008). [PubMed]

A Novel and Compact Low-Pass Quasi-Elliptic Filter using Hybrid Microstrip/CPW Structure

A novel and compact lowpass quasi-elliptic filter with harmonic-suppressed, sharp-rejection slope, wide and deep stop-band attenuation properties is presented. The filter is composed of CPW short-circuited resonators at the bottom of substrate and microstrip shunt open-circuited resonators at the top of substrate. Based on this hybrid microstrip/CPW structure, the LPF with excellent electrical performances is simulated and optimized by the momentum of method (MoM). A demonstration filter with 3 dB cutoff frequency at 3.6 GHz is designed, fabricated and measured. Measured results exhibit a good low-pass performance, including a low loss in the passband from 0.2 to 3.4 GHz, and wide and deep attenuation in the stopband from 4.2 to 16 GHz.

Automotive engine air intake system with variable noise control

Engine air intake systems are routinely tasked with delivering a specific target sound which involves meeting an overall noise level and, in many cases, desired frequency content over the entire engine speed range. In order to meet these targets, it is generally necessary to incorporate one or more reactive tuning devices, such as Helmholtz resonators, into the intake system. Traditional devices provide deep attenuation at their designed frequency, but they also introduce undesirable sideband resonances at a higher and a lower frequency. Even after the addition of several devices, it may still not be possible to match the desired intake noise targets due to their deep attenuation and sideband amplification. The subject of this work is to introduce an electronically controlled variable noise control (VNC) device for engine air intake systems which is capable of adjusting the air intake system’s frequency response as commanded by the engine operating conditions. The VNC device permits the desired amount of attenuation of peaks in the air intake noise without introducing undesirable sideband resonances. In addition, because the tuning is controlled electronically, the VNC device can deliver a target-specific response using the same hardware across multiple vehicle programs.

A novel compact K band PBG microstrip structure band-pass filter

A novel K band band-pass filter based on photonic band-gap (PBG) is presented. The proposed structures exhibit low insertion loss, compact size, simple fabrication and slow-wave characteristics. Due to slow-wave characteristic, PBG structure minimizes the pass-band filter to one-tenth of conventional filters with spurious-free response and deep attenuation levels. The miniature band-pass filter was simulated, realized and measured. There is a good agreement between the experiment and simulation results had been achieved. Its center pass-band frequency of this filter is 25.2 GHz, and insertion loss is less than −4.5 dB.

A novel method for predicting site dependent specific rain attenuation of millimeter radio waves

There is a need for validation and improvement of propagation prediction methods for the safe design and operation of millimeter radio communication systems. At this frequency range, propagation related degradation is primarily caused by rainfall. Our goal is an improved method for predicting specific attenuation due to rainfall. A general method for establishing the relationship between rainfall rate and specific attenuation is developed. Drop size distributions (DSDs) measured by a Joss distrometer are analyzed, and three climate classification parameters, rain rate, DSD median, and DSD mode, are used in the development of the new methods. These parameters are investigated as candidate classes to categorize drop size distributions. Categories of the classes are then established to improve the long-term DSD estimate. The typical long-term DSD is used to derive new prediction methods that are compared with observed attenuation. The influence of wind on the rainfall measurements is studied, and a corresponding correction is suggested, reducing the prediction error significantly. Testing of the three new methods using measurements at 40 and 60 GHz shows noticeable improvement over the method recommended by the International Telecommunication Union (ITU) using measurements at 60 GHz at deep attenuation.