Publications by authors named "Andrey Morozov"

31 Publications

Postoperative medical treatment of lower urinary tract symptoms after benign prostatic hyperplasia surgery. Are we underestimating the problem?

Curr Opin Urol 2021 Jun 25. Epub 2021 Jun 25.

Institute for Urology and Reproductive Health International School 'Medicine of the Future', Sechenov University, Moscow, Russia.

Purpose Of Review: The aim of this study was to determine whether well timed start of medical and surgical treatment of benign prostatic obstruction (BPO) influences the treatment's effectiveness and thus the patients' overall functional outcomes and quality of life.

Recent Findings: Pharmacological therapy even in high-volume (>80 cm3) BPH typically begins with α-blockers sole and only subsequently are 5ARI added. Several studies showed that acute urinary retention (AUR) developed more frequently in men who suffered severe lower urinary tract symptoms (LUTS) and who did not start combination therapy immediately. Moreover, there are no strict criteria which determine the right time for performing surgery in patients with mild and moderate LUTS, especially when pharmacological therapy fails. However, sometimes, the surgery does not eliminate all the symptoms, as it deals effectively with BPO, but does not treat an overactive bladder. Also, data show that surgery should be performed as soon as possible and be more radical after the first episode of AUR.

Summary: A combination of α-blockers and 5ARI makes for a good starting point where the treatment of high volume BPH is concerned. Ideally, surgery should be performed immediately or as soon as possible in patients with the first episode of AUR and 'anatomic' BPH tissue removal is preferable (dissection of tissue along the prostate capsule to remove its maximum volume).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/MOU.0000000000000912DOI Listing
June 2021

Underwater ultra-low frequency seismic source.

Authors:
Andrey K Morozov

J Acoust Soc Am 2021 Apr;149(4):2163

Teledyne Marine, North Falmouth, Massachusetts 02556, USA.

The ultra-low frequency band (2-8 Hz) is of interest for geophysical research due to advances in the field of full waveform inversion and elastic impedance measurements. Generating sound in the ultra-low frequency range is a difficult task. A powerful source with an ultra-low frequency should be able to displace hundreds of liters of water per cycle. The amplitude of internal pressure fluctuations is comparable to the difference in buoyancy forces on the radiation aperture, and acoustic-gravitational effects are part of its hydrodynamics. The source described in this article has a pneumatically driven bubble resonator and provides a volume displacement and radiation area that are larger than other known prototypes. The article examines the acoustic physics of a large underwater bubble resonator and a seismic bubble source with an internal Helmholtz resonator. A finite element analysis of the transition of near-field hydrodynamics to a pressure wave is included, as well as a treatment of transition loss and broadband radiation methods. The study concludes with the creation and testing of an ultra-low frequency seismic source. Experiments carried out at the Woods Hole Oceanographic Institution showed that the prototype has a source level high enough for full waveform inversion in geophysical surveys.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1121/10.0003953DOI Listing
April 2021

A systematic review and meta-analysis of Histoscanning™ in prostate cancer diagnostics.

World J Urol 2021 Apr 7. Epub 2021 Apr 7.

Institute for Urology and Reproductive Health, Sechenov University, Bolshaya Pirogovskaya str. 2 bld. 1, Moscow, 119991, Russia.

Context: The value of Histoscanning™ (HS) in prostate cancer (PCa) imaging is much debated, although it has been used in clinical practice for more than 10 years now.

Objective: To summarize the data on HS from various PCa diagnostic perspectives to determine its potential.

Materials And Methods: We performed a systematic search using 2 databases (Medline and Scopus) on the query "Histoscan*". The primary endpoint was HS accuracy. The secondary endpoints were: correlation of lesion volume by HS and histology, ability of HS to predict extracapsular extension or seminal vesicle invasion.

Results: HS improved cancer detection rate "per core", OR = 16.37 (95% CI 13.2; 20.3), p < 0.0001, I = 98% and "per patient", OR = 1.83 (95% CI 1.51; 2.21), p < 0.0001, I = 95%. The pooled accuracy was markedly low: sensitivity - 0.2 (95% CI 0.19-0.21), specificity - 0.12 (0.11-0.13), AUC 0.12. 8 of 10 studiers showed no additional value for HS. The pooled accuracy with histology after RP was relatively better, yet still very low: sensitivity - 0.56 (95% CI 0.5-0.63), specificity - 0.23 (0.18-0.28), AUC 0.4. 9 of 12 studies did not show any benefit of HS.

Conclusion: This meta-analysis does not see the incremental value in comparing prostate Histoscanning with conventional TRUS in prostate cancer screening and targeted biopsy. HS proved to be slightly more accurate in predicting extracapsular extension on RP, but the available data does not allow us to draw any conclusions on its effectiveness in practice. Histoscanning is a modification of ultrasound for prostate cancer visualization. The available data suggest its low accuracy in screening and detecting of prostate cancer.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00345-021-03684-8DOI Listing
April 2021

hTERT, hTR and TERT promoter mutations as markers for urological cancers detection: A systematic review.

Urol Oncol 2021 Mar 3. Epub 2021 Mar 3.

Institute for Urology and Reproductive Health, Sechenov University, Moscow, Russia. Electronic address:

The clinical relevance of telomerase subunits (human reverse transcriptase - hTERT, and human telomerase RNA - hTR) and TERT promotor mutations as biomarkers in genitourinary cancers was reviewed through the systematic analysis of the current literature. We performed a systematic literature search using 2 databases (Medline and Scopus) over the past 20 years. Primary outcomes were sensitivity and specificity of hTR, hTERT and TERT promoter mutations. Secondary outcomes were the biomarkers predictive values for tumor characteristics. Regarding bladder cancer, hTERT in urine showed high sensitivity (mean values: 55%-96%), and specificity (69%-100%): it correlated with bladder cancer grade and/or stage. hTR sensitivity ranged from 77% to 92%. With adapted cut-off, it demonstrated 72% to 89% specificity. TERT promoter mutation rate was up to 80% both in tissue and urine, resulting in 62%-92% sensitivity for primary tumors and 42% for relapse. Specificity ranged from 73% to 96%, no correlations with stage were observed. In prostate cancer, hTERT in tissue, prostate secretion and serum showed high sensitivity (97.9%, 36%, and 79.2%-97.5%, respectively) and specificity values (70%, 66%, 60%-100%). hTR showed very high sensitivity (88% in serum and 100% in tissue) although specificity values were highly variable depending on the series and techniques (0%-96.5%). In RCC, hTERT sensitivity on tissue ranged from 90 to 97%, specificity from 25 to 58%. There was an association of hTERT expression with tumor stage and grade. hTERT showed high accuracy in genitourinary cancers, while the value of hTR was more controversial. hTERT and TERT promotor mutations may have predictive value for bladder cancer and RCC staging and grading, while no such relationship was observed in CaP. Although telomerase subunits showed clinically relevant values in genitourinary cancers, developing fast and cost-effective methods is required before contemplating routine use.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.urolonc.2021.01.022DOI Listing
March 2021

A systematic review of nerve-sparing surgery for high-risk prostate cancer.

Minerva Urol Nephrol 2021 Jun 13;73(3):283-291. Epub 2021 Jan 13.

Institute for Urology and Reproductive Health, Sechenov University, Moscow, Russia.

Introduction: We provide a systematic analysis of nerve-sparing surgery (NSS) to assess and summarize the risks and benefits of NSS in high-risk prostate cancer (PCa).

Evidence Acquisition: We have undertaken a systematic search of original articles using 3 databases: Medline/PubMed, Scopus, and Web of Science. Original articles in English containing outcomes of nerve-sparing radical prostatectomy (RP) for high-risk PCa were included. The primary outcomes were oncological results: the rate of positive surgical margins and biochemical relapse. The secondary outcomes were functional results: erectile function (EF) and urinary continence.

Evidence Synthesis: The rate of positive surgical margins differed considerably, from zero to 47%. The majority of authors found no correlation between NSS and a positive surgical margin rate. The rate of biochemical relapse ranged from 9.3% to 61%. Most of the articles lacked data on odds ratio (OR) for positive margin and biochemical relapse. The presented results showed no effect of nerve sparing (NS) on positive margin (OR=0.81, 0.6-1.09) or biochemical relapse (hazard ratio [HR]=0.93, 0.52-1.64). A strong association between NSS and potency rate was observed. Without NSS, between 0% and 42% of patients were potent, with unilateral 79-80%, with bilateral - up to 90-100%. Urinary continence was not strongly associated with NSS and was relatively good in both patients with and without NSS.

Conclusions: NSS may provide benefits for patients with urinary continence and significantly improves EF in high-risk patients. Moreover, it is not associated with an increased risk of relapse in short- and middle-term follow-up. However, the advantages of using such a surgical technique are unclear.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.23736/S0393-2249.20.04178-8DOI Listing
June 2021

Endoscopic lithotripsy with a SuperPulsed thulium-fiber laser for ureteral stones: A single-center experience.

Int J Urol 2021 03 30;28(3):261-265. Epub 2020 Nov 30.

Institute for Urology and Reproductive Health, Sechenov University, Moscow, Russia.

Objectives: To estimate the efficacy and safety of SuperPulsed thulium-fiber laser ureteral lithotripsy and to identify optimal laser settings.

Methods: Patients with solitary stones were prospectively included. Lithotripsy was performed with a SuperPulsed thulium-fiber laser (NTO IRE-Polus, Fryazino, Russia) using a rigid ureteroscope 7.5 Ch (Richard Wolf, Knittlingen, Germany). We analyzed the efficacy of lithotripsy by measuring total energy required for stone disintegration, "laser-on" time, ablation speed, ablation efficacy, and energy consumption. Stone retropulsion and visibility were assessed using a three-point Likert scale. Complications were assessed using the Clavien-Dindo classification system.

Results: A total of 149 patients were included. The mean stone density was 985 ± 360 Hounsfield units, the median (interquartile range) stone volume was 179 (94-357) mm . The median (interquartile range) total energy was 1 (0.4-2) kJ, and laser-on time 1.2 (0.5-2.7) min. The median (interquartile range) stone ablation speed was 140 (80-279) mm /min, energy for ablation of 1 mm was 5.6 (3-9.9) J/mm and energy consumption was 0.9 (0.6-1) J/min. A correlation was found between retropulsion and the energy used (r = 0.5, P < 0.001). Multivariable analysis showed energy to be a predictor of increased retropulsion (odds ratio 65.7, 95% confidence interval 1.6-2774.1; P = 0.028). No predictors for worse visibility were identified.

Conclusion: The SuperPulsed thulium-fiber laser provides effective and safe lithotripsy during ureteroscopy regardless of stone density. Fiber diameter and laser frequency do not influence visibility or safety. Optimal laser settings are 0.5 J × 30 Hz for fragmentation and 0.15 J × 100 Hz for dusting.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/iju.14443DOI Listing
March 2021

Identification of Clinically Significant Prostate Cancer by Combined and mRNA Detection in Urine Samples.

Res Rep Urol 2020 17;12:403-413. Epub 2020 Sep 17.

Department of Molecular Biology and Genetics, Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russia.

Purpose: Preclinical evaluation of and transcript simultaneous detection in urine to diagnose clinical significant prostate cancer (prostate cancer with Gleason score ≥7) in a Russian cohort.

Patients And Methods: We analyzed urine samples of patients with a total serum PSA ≥2 ng/mL: 31 men with prostate cancer scheduled for radical prostatectomy, 128 men scheduled for first diagnostic biopsy (prebiopsy cohort). , , and transcripts were detected by multiplex reverse transcription quantitative polymerase chain reaction, and the results were used for scores for calculation and statistical analysis.

Results: There was no significant difference between clinically significant and nonsignificant prostate cancer PCA3 scores. However, there was a significant difference in the AMACR score (patients scheduled for radical prostatectomy =0.0088, prebiopsy cohort =0.029). We estimated AUCs, optimal cutoffs, sensitivities and specificities for PCa and csPCa detection in the prebiopsy cohort by tPSA, PCA3 score, PCPT Risk Calculator and classification models based on tPSA, PCA3 score and AMACR score. In the clinically significant prostate cancer ROC analysis, the PCA3 score AUC was 0.632 (95%CI: 0.511-0.752), the AMACR score AUC was 0.711 (95%CI: 0.617-0.806) and AUC of classification model based on the score, the AMACR score and total PSA was 0.72 (95%CI: 0.58-0.83). In addition, the correlation of the AMACR score with the ratio of total RNA and RNA of prostate cells in urine was shown (tau=0.347, =6.542e-09). Significant amounts of nonprostate RNA in urine may be a limitation for the AMACR score use.

Conclusion: The AMACR score is a good predictor of clinically significant prostate cancer. Significant amounts of nonprostate RNA in urine may be a limitation for the AMACR score use. Evaluation of the AMACR score and classification models based on it for clinically significant prostate cancer detection with larger samples and a follow-up analysis is promising.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2147/RRU.S262310DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7505712PMC
September 2020

Systematic review of the endoscopic enucleation of the prostate learning curve.

World J Urol 2020 Sep 17. Epub 2020 Sep 17.

Department of Urology, Spital Thurgau AG, Pfaffenholzstrasse 4, 8501, Frauenfeld, Switzerland.

Introduction: It has been shown that endoscopic enucleation of the prostate (EEP) allows for similar efficacy and safety, no matter what energy and type of instruments we use, but the length of learning may differ greatly. The aim of this systematic review is to verify if there is any significant difference between EEP methods in learning.

Evidence Acquisition: We performed a systematic literature search in three databases and included only the articles containing their own data on the EEP learning curve assessment during the last 10 years. The primary endpoint was to determine the necessary experience needed to achieve a plateau. The secondary endpoints were to review methods used to evaluate a learning curve.

Evidence Synthesis: The final sample included 17 articles, containing a total of 4615 EEPs performed by 76 surgeons, the most common method was HoLEP (9/17). The majority of articles studying HoLEP report a learning curve of experience level achievement in roughly 30-40 (min 20; max 60) cases. The studies of GreenLight laser showed high heterogeneity in the results with minimum of 20 cases and maximum of 150-200 cases. TUEB required roughly 40-50 cases to reach the plateau.

Conclusion: Although EEP is considered challenging, it shows a steep learning curve with a plateau after 30-50 cases. Proper criteria are critical for accurate assessment of the learning curve. The Trifecta and Pentafecta criteria are currently the most appropriate method to evaluate EEP learning.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00345-020-03451-1DOI Listing
September 2020

A systematic review of irreversible electroporation in localised prostate cancer treatment.

Andrologia 2020 Nov 12;52(10):e13789. Epub 2020 Aug 12.

Institute for Urology and Reproductive Health, Sechenov University, Moscow, Russia.

Irreversible electroporation is a treatment option used for focal therapy. In this systematic review, we summarise data on irreversible electroporation outcomes in patients with localised prostate cancer. We performed a literature search in 3 databases and included articles with own data on irreversible electroporation results in patients with localised prostate cancer. Primary outcome was procedure efficacy measured as the absence of cancer in the treatment area on the follow-up biopsy. Secondary outcomes were the absence of prostate cancer recurrence in the treatment area on MRI, out-of-field recurrence, complications and functional outcomes (erectile function and micturition). In-field recurrence rate was 0%-39% and out-field 6.4%-24%. In all studies, PSA level decreased: twice lower than baseline after 4 weeks and by 76% after 2 years. Most of the authors noted sexual and urinary toxicity during the first half year after surgery. However, functional outcomes recovered to baseline after 6 months with mild decrease in sexual function. Complication rates after irreversible electroporation were 0%-1% of Clavien-Dindo III and 5%-20% of Clavien-Dindo I-II. Irreversible electroporation has promise oncological outcomes, rate of post-operative complications and minimal-to-no effects on erectile and urinary function. However, medium and long-term data on cancer-specific and recurrence-free survival are still lacking.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/and.13789DOI Listing
November 2020

Active Surveillance for Intermediate-Risk Prostate Cancer: Systematic Review and Meta-analysis of Current Protocols and Outcomes.

Clin Genitourin Cancer 2020 12 22;18(6):e739-e753. Epub 2020 May 22.

Institute for Urology and Reproductive Health, Sechenov University, Moscow, Russia.

Introduction: Current guidelines allow active surveillance for intermediate-risk prostate cancer patients but do not provide comprehensive recommendations for selection. We performed a systematic review and meta-analysis of outcomes for active surveillance in intermediate- and low-risk groups.

Methods: We performed a systematic literature search of intermediate-risk localized prostate cancer patients undergoing active surveillance using 3 literature search engines (Medline, Web of Science, and Scopus) over the past 10 years. The primary outcome was the percentage of patients who remain under surveillance. Secondary outcomes included cancer-specific survival, overall survival, and metastasis-free survival. For articles including both low- and intermediate-risk patients undergoing active surveillance, comparisons between the two groups were made.

Results: The proportion of patients who remained on active surveillance was comparable between the low- and intermediate-risk groups after 10 and 15 years' follow-up (odds ratio [OR], 0.97; 95% confidence interval [CI], 0.83-1.14; and OR, 0.86; 95% CI, 0.65-1.13). Cancer-specific survival was worse in the intermediate-risk group after 10 years (OR, 0.47; 95% CI, 0.31-0.69) and 15 years (OR, 0.34; 95% CI, 0.2-0.58). The overall survival rate showed no statistical difference at 5 years' follow-up (OR, 0.84; 95% CI, 0.45-1.57) but was worse in the intermediate-risk group after 10 years (OR, 0.43; 95% CI, 0.35-0.53). Metastases-free survival did not significantly differ after 5 years (OR, 0.55; 95% CI, 0.2-1.53) and was worse in the intermediate-risk group after 10 years (OR, 0.46; 95% CI, 0.28-0.77).

Conclusion: Active surveillance could be offered to patients with intermediate-risk prostate cancer. However, they should be informed of the need for regular monitoring and the possibility of discontinuation as a result of a higher rate of progression. Available data indicate that 5-year survival rates between intermediate- and low-risk patients do not differ; 10-year survival rates are worse. To assess the long-term effectiveness and safety of active surveillance, it is necessary to develop unified algorithms for patient selection and management, and to prospectively conduct studies with long-term surveillance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clgc.2020.05.008DOI Listing
December 2020

Focal irreversible electroporation for localized prostate cancer management: prospective assessment of efficacy and safety.

Minerva Urol Nefrol 2020 10 7;72(5):644-645. Epub 2020 Jul 7.

Institute for Urology and Reproductive Health, Sechenov University, Moscow, Russia.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.23736/S0393-2249.20.03840-0DOI Listing
October 2020

Long-Term Outcomes of Holmium Laser Enucleation of the Prostate: A 5-Year Single-Center Experience.

J Endourol 2020 Oct 4;34(10):1055-1063. Epub 2020 Aug 4.

Institute for Urology and Reproductive Health, Sechenov University, Moscow, Russia.

To analyze the long-term efficacy and safety of holmium laser enucleation of the prostate (HoLEP) for benign prostatic hyperplasia. A total of 127 patients who underwent HoLEP at our institution between 2013 and 2015 were included. Patients were observed for 5 years postoperatively. We evaluated the length of the surgery, the mass of the removed tissue, prostate-specific antigen level, the maximal flow rate (Qmax), postvoid residual (PVR), the length of catheterization and hospitalization, and the International Prostate Symptom Score (IPSS) and IPSS quality of life (QoL) at each clinic visit. PVR, Qmax, IPSS, and QoL all improved significantly immediately after the operation ( < 0.001). By the end of the 5th postoperative year, all the parameters showed a statistically meaningful decline: Qmax reduced by 5.8 mL/s (22.6%) and IPSS by 1.4 points (29.1%). Around 8.6% of the patients continued therapy with α-blockers. There were no differences in efficacy by the age of the patients or the volume of the prostate. Long-term complications and need for repeat operations were not affected by the volume of the prostate or patient age. The improvement of PVR, Qmax, IPSS, and QoL score seen in the early postoperative period after performing HoLEP remains evident at 5 years postoperatively. Long-term complications and the need for reoperation do not depend on the age of the patient or on the initial volume of the prostate.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1089/end.2020.0347DOI Listing
October 2020

Retrospective Assessment of Endoscopic Enucleation of Prostate Complications: A Single-Center Experience of More Than 1400 Patients.

J Endourol 2020 02;34(2):192-197

Institute for Urology and Reproductive Health, Sechenov University, Moscow, Russia.

Endoscopic enucleation of the prostate (EEP) is a safe method of treating benign prostatic hyperplasia, regardless of prostate volume and type of applied energy. To date, however, there has been no study that examines complication rates with respect to the type of applied energy. This study aims to address this problem by providing a retrospective analysis of >1400 patients who have undergone prostate enucleation. We performed a retrospective analysis of all patients undergoing EEP between 2013 and 2018 at a single tertiary institution. This analysis included patients who had undergone one of three forms of EEP: holmium laser enucleation of the prostate (HoLEP), thulium fiber laser enucleation of the prostate (ThuFLEP), or monopolar enucleation of the prostate (MEP). We compared intraoperative and early postoperative complications, as well as complications at 3 and 6 months follow-up. A total of 1413 patients were included in this study; 36% patients underwent HoLEP, 57.5% had ThuFLEP, and 6.5% MEP. The most frequent complication in the early postoperative period was a mild fever (2.76% of the cases). The morcellation was delayed to a separate stage because of intensive hemorrhaging in 1.4% of the cases. Bladder tamponade was found in 1.1% of the cases. We found no correlation between complication rate and either prostate volume or energy source. Stress urinary incontinence was found in 3.9% of patients at 3 months and in only 1.4% of patients at 6 months after the operation. Urethral stricture at 6 months after the surgery was found in 1.4% of patients, whereas bladder neck sclerosis was found in only 0.9% of these cases. No significant difference was observed between these complication frequencies and any preoperative factors or energy source. All EEP types are safe with equal rates of complications intraoperatively, postoperatively, and at 6 months follow-up.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1089/end.2019.0630DOI Listing
February 2020

The Role of Cysteine Cathepsins in Cancer Progression and Drug Resistance.

Int J Mol Sci 2019 Jul 23;20(14). Epub 2019 Jul 23.

Institute of Molecular Medicine, Sechenov First Moscow State Medical University, 119991 Moscow, Russia.

Cysteine cathepsins are lysosomal enzymes belonging to the papain family. Their expression is misregulated in a wide variety of tumors, and ample data prove their involvement in cancer progression, angiogenesis, metastasis, and in the occurrence of drug resistance. However, while their overexpression is usually associated with highly aggressive tumor phenotypes, their mechanistic role in cancer progression is still to be determined to develop new therapeutic strategies. In this review, we highlight the literature related to the role of the cysteine cathepsins in cancer biology, with particular emphasis on their input into tumor biology.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijms20143602DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6678516PMC
July 2019

Description of Transfer Processes in a Locally Nonequilibrium Medium.

Authors:
Andrey N Morozov

Entropy (Basel) 2018 Dec 23;21(1). Epub 2018 Dec 23.

Bauman Moscow State Technical University, 2nd Baumanskaya str., 5, Moscow 105005, Russia.

This paper presents a description of the fluctuations in transfer processes in a locally nonequilibrium medium. We obtained equations which allow the fluctuations range to be determined for a transferred physical value. It was shown that the general method of describing fluctuations for the processes of diffusion, heat transfer, and viscous fluid flow can be applied. It was established that the fluctuation spectrum during the transfer processes has the character of flicker noise in the low-frequency spectral range.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/e21010009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7514200PMC
December 2018

First-order optical spatial differentiator based on a guided-mode resonant grating.

Opt Express 2018 Apr;26(8):10997-11006

We present an experimental demonstration of a subwavelength diffraction grating performing first-order differentiation of the transverse profile of an incident optical beam with respect to a spatial variable. The experimental results are in a good agreement with the presented analytical model suggesting that the differentiation is performed in transmission at oblique incidence and is associated with the guided-mode resonance of the grating. According to this model, the transfer function of the grating in the vicinity of the resonance is close to the transfer function of an exact differentiator. We confirm this by estimating the transfer function of the fabricated structure on the basis of the measured profiles of the incident and transmitted beams. The considered structure may find application in the design of new photonic devices for beam shaping, optical information processing, and analog optical computing.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.26.010997DOI Listing
April 2018

Multifocal diffractive lens generating several fixed foci at different design wavelengths.

Opt Express 2018 Feb;26(4):4698-4709

We propose a method for designing multifocal diffractive lenses generating prescribed sets of foci with fixed positions at several different wavelengths. The method is based on minimizing the difference between the complex amplitudes of the beams generated by the lens microrelief at the design wavelengths, and the functions of the complex transmission of multifocal lenses calculated for these wavelengths. As an example, a zone plate generating three fixed foci at three different wavelengths was designed, fabricated, and experimentally investigated. The proof-of-concept experimental results confirm the formation of foci with fixed positions at the design wavelengths. The obtained results may find applications in the design and fabrication of novel multifocal contact and intraocular lenses with reduced chromatic effects.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.26.004698DOI Listing
February 2018

Equations for normal-mode statistics of sound scattering by a rough elastic boundary in an underwater waveguide, including backscattering.

J Acoust Soc Am 2017 09;142(3):EL292

Department of Oceanography Graduate School of Engineering and Applied Sciences, Naval Postgraduate School, 833 Dyer Road, Monterey, California 93943, USA

Underwater sound scattering by a rough sea surface, ice, or a rough elastic bottom is studied. The study includes both the scattering from the rough boundary and the elastic effects in the solid layer. A coupled mode matrix is approximated by a linear function of one random perturbation parameter such as the ice-thickness or a perturbation of the surface position. A full two-way coupled mode solution is used to derive the stochastic differential equation for the second order statistics in a Markov approximation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1121/1.5002734DOI Listing
September 2017

Near-infrared fluorescence with indocyanine green for diagnostics in urology: initial experience.

Urologia 2017 Aug 16;84(3):197-202. Epub 2017 May 16.

Department of Urology, I.M. Sechenov First Moscow State Medical University, Moscow - Russia.

Introduction: Fluorescence imaging with indocyanine green is used in urology for the detection of sentinel lymph nodes and identification of prostate margins in radical prostatectomy for delineation of resection zone and selective clamping of vessels in partial nephrectomy; for identification and evaluation of length of ureteral strictures; for assessment of perfusion and viability of anastomoses during reconstructive stage of cystectomy. Safety of this technique is proven, while its diagnostic value and usefulness is still controversial.

Methods: This pilot study of using the SPY Elite Fluorescence Imaging System for diagnostics was performed in the I.M. Sechenov First Moscow State Medical University. Ten patients were enrolled: four patients underwent retropubic RP and lymph node dissection, five patients underwent partial nephrectomy, and one patient underwent ureteroplasty. Fluorophore was injected transrectally with TRUS guidance during RP in order to assess the lymph nodes. During partial nephrectomy, the compound was injected intravenously to differentiate the tumor from parenchyma by its blood supply. During ureteroplasty, the indocyanine green solution was injected into the renal pelvis to dye the ureter and locate the stricture.

Results: Sensitivity of this technique for visualization of sentinel lymph nodes was 100%, and specificity was 73.3%. In patients who underwent partial nephrectomy, all lesions were malignant and hypofluorescent when compared with healthy parenchyma. SPY allowed us to determine the location and extension of the stricture during ureteroplasty. No hypersensitivity reactions or complications were observed during injection of the compound.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.5301/uj.5000235DOI Listing
August 2017

Entropy rate defined by internal wave scattering in long-range propagation.

J Acoust Soc Am 2015 Sep;138(3):1353-64

Department of Oceanography Graduate School of Engineering and Applied Sciences, Naval Postgraduate School, 833 Dyer Road, Monterey, California 93943, USA.

The reduction of information capacity of the ocean sound channel due to scattering by internal waves is a potential problem for acoustic communication, navigation, and remote sensing over long ranges. In spite of recent progress in research on acoustic signal scattering by random internal waves and the fact that random internal waves are ubiquitous in the world oceans, there is no clear understanding of how these waves influence data communication performance. The entropy decrease resulting from scattering by internal waves is an important measure of information loss. Here a rigorous calculation of the entropy is carried out using second moment transport theory equations with random sound-speed perturbations obeying the Garrett-Munk internal-wave model. It is shown that full-wave rate of entropy is of the same order of magnitude as the Kolmogorov-Sinai entropy and Lyapunov exponents for the relevant ray trajectories. The correspondence between full-wave and ray entropies suggests a correspondence between full-wave scattering and ray chaos near statistical saturation. The relatively small level of entropy rate during propagation through the random internal-wave field shows that scattering by internal waves is likely not an essential limitation for data rate and channel capacity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1121/1.4928617DOI Listing
September 2015

Structure and Properties of Platinum, Gold and Mercury Nanowires Grown in Superfluid Helium.

J Phys Chem Lett 2014 Apr 14;5(7):1072-6. Epub 2014 Mar 14.

∥Institute of Microelectronics Technology and High Purity Materials RAS, Institutskaya Street, 6, 142432, Chernogolovka, Moscow Region, Russian Federation.

Webs consisting of nanowires made of gold, platinum and mercury were produced by the technique based on laser ablation of metals inside superfluid helium. Their morphology and structure as well as their electrical conductivity have been studied. Diameters of gold and platinum nanowires are 4.5 and 3 nm, respectively. Fortunately, they are close to diameters of nanospheres made of these metals, which, as known from the literature, possess anomalous catalytic activity. Web resistivities for all metals up to room temperature are controlled by conductive electron scattering on a wire surface, thus they are almost independent of T. Nanowires in the webs are electrically interconnected, and therefore the web can be used as a catalyst without any support. Possible advantages of this type of nanocatalyst are outlined.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jz5003583DOI Listing
April 2014

Scaling up the predator functional response in heterogeneous environment: when Holling type III can emerge?

J Theor Biol 2013 Nov 25;336:200-8. Epub 2013 Jul 25.

Aix-Marseille Université, Université du Sud Toulon-Var, CNRS/INSU, IRD, MIO, UM 110, 13288 Marseille, Cedex 09, France; Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, One Shields Ave, Davis, CA 95616. Electronic address:

Accurate parametrization of functional terms in model equations is of great importance for reproducing the dynamics of real food webs. Constructing models over large spatial and temporal scales using mathematical expressions obtained based on microcosm experiments can be erroneous. Here, using a generic spatial predator-prey model, we show that scaling up the microscale functional response of a predator can result in qualitative alterations of functional response on macroscales. In particular, a global functional response of sigmoid type (Holling type III) can emerge as a result of non-linear averaging of non-sigmoid local responses (Holling type I or II). We demonstrate that alteration between the local and the global response in the model is a result of the interplay between density-dependent dispersal of the predator across the habitat and heterogeneity of the environment. Using the method of aggregation of variables, we analytically derive the mathematical formulation of the global functional response as a function of the total amount of prey in the system, and reveal the key parameters which control the emergence of a Holling type III global response. We argue that this mechanism by which a global Holling type III emerges from a local Holling type II response has not been reported in the literature yet: in particular, Holling type III can emerge in the case of a fixed gradient of resource distribution across the habitat, which would be impossible in priorly suggested mechanisms. As a case study, we consider the interaction between phytoplankton and zooplankton grazers in the water column; and we show that the emergence of a Holling type III global response can allow for the efficient top-down regulation of primary producers and stabilization of planktonic ecosystems under eutrophic conditions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jtbi.2013.07.011DOI Listing
November 2013

Per-survivor processing for underwater acoustic communications with direct-sequence spread spectrum.

J Acoust Soc Am 2013 May;133(5):2746-54

Department of Electrical and Computer Engineering, University of Connecticut, 371 Fairfield Road Unit 2157, Storrs, Connecticut 06269, USA.

This paper proposes a receiver for direct-sequence spread spectrum transmissions in underwater acoustic channels, which combines a per-survivor processing (PSP) structure with sparse channel estimation. Specifically, the PSP structure establishes the trellis on the symbol level to render a small to moderate number of states, thus reducing the computational complexity. Meanwhile, the sparse channel estimation is performed on the chip level, where the orthogonal matching pursuit algorithm is used and a two-dimensional grid of path delay and Doppler scaling factor is incorporated in the dictionary construction. The effective combination of the PSP detection and sparse channel estimation achieves a good tradeoff between performance and complexity. Simulation and experiment results show that the proposed receiver outperforms the conventional RAKE receiver considerably, and most importantly, the proposed PSP receiver with an exact wideband dictionary maintains an excellent performance even for challenging underwater acoustic channels with large Doppler disparities on different paths.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1121/1.4796130DOI Listing
May 2013

Simultaneous photoacoustic and optically mediated ultrasound microscopy: phantom study.

Opt Lett 2012 Nov;37(22):4606-8

Institute of Applied Physics, 46 Ul’yanov Street, Nizhny Novgorod 603950, Russia.

An experimental setup for combined photoacoustic (PA) and optically mediated ultrasound (US) microscopy is presented. A spherically focused 35 MHz polyvinylidene fluoride (PVDF) ultrasonic detector with a numerical aperture of 0.28, a focal distance of 9 mm, and a bandwidth (-6 dB level) of 24 MHz was used to obtain PA and US data with a 3 mm imaging depth. A fiber-optic system was employed to deliver laser excitation pulses from a tunable laser to the studied medium. A single optical pulse was used to form both PA and US A-scans. The probing US pulses were generated thermoelastically due to absorption of backscattered laser radiation by the metalized surface of a PVDF film.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/ol.37.004606DOI Listing
November 2012

Statistics of low-frequency normal-mode amplitudes in an ocean with random sound-speed perturbations: shallow-water environments.

J Acoust Soc Am 2012 Feb;131(2):1749-61

Department of Oceanography, Naval Postgraduate School Monterey, California 93943, USA.

Second- and fourth-moment mode-amplitude statistics for low-frequency ocean sound propagation through random sound-speed perturbations in a shallow-water environment are investigated using Monte Carlo simulations and a transport theory for the cross-mode coherence matrix. The acoustic observables of mean and mean square intensity are presented and the importance of adiabatic effects and cross-mode coherence decay are emphasized. Using frequencies of 200 and 400 Hz, transport theory is compared with Monte Carlo simulations in a canonical shallow-water environment representative of the summer Mid-Atlantic Bight. Except for ranges less than a horizontal coherence length of the sound structure, the intensity moments from the two calculations are in good agreement. Corrections for the short range behavior are presented. For these frequencies the computed mode coupling rates are extremely small, and the propagation is strongly adiabatic with a rapid decay of cross-mode coherence. Coupling effects are predicted to be important at kilohertz frequencies. Decay of cross-mode coherence has important implications for acoustic interactions with nonlinear internal waves: For the case in which the acoustic path is not at glancing incidence with a nonlinear internal-wave front, adiabatic phase randomizing effects lead to a significantly reduced influence of the nonlinear waves on both mean and mean square intensity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1121/1.3666002DOI Listing
February 2012

Physically constrained maximum likelihood mode filtering.

J Acoust Soc Am 2010 Apr;127(4):2385-91

Woods Hole Oceanographic Institution, MS 44, Woods Hole, Massachusetts 02543, USA.

Mode filtering is most commonly implemented using the sampled mode shapes or pseudoinverse algorithms. Buck et al. [J. Acoust. Soc. Am. 103, 1813-1824 (1998)] placed these techniques in the context of a broader maximum a posteriori (MAP) framework. However, the MAP algorithm requires that the signal and noise statistics be known a priori. Adaptive array processing algorithms are candidates for improving performance without the need for a priori signal and noise statistics. A variant of the physically constrained, maximum likelihood (PCML) algorithm [A. L. Kraay and A. B. Baggeroer, IEEE Trans. Signal Process. 55, 4048-4063 (2007)] is developed for mode filtering that achieves the same performance as the MAP mode filter yet does not need a priori knowledge of the signal and noise statistics. The central innovation of this adaptive mode filter is that the received signal's sample covariance matrix, as estimated by the algorithm, is constrained to be that which can be physically realized given a modal propagation model and an appropriate noise model. Shallow water simulation results are presented showing the benefit of using the PCML method in adaptive mode filtering.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1121/1.3327799DOI Listing
April 2010

Statistics of normal mode amplitudes in an ocean with random sound-speed perturbations: cross-mode coherence and mean intensity.

J Acoust Soc Am 2009 Sep;126(3):1026-35

Department of Oceanography, Naval Postgraduate School, Monterey, CA 93943, USA.

In this paper Creamer's [(1996). J. Acoust. Soc. Am. 99, 2825-2838] transport equation for the mode amplitude coherence matrix resulting from coupled mode propagation through random fields of internal waves is examined in more detail. It is shown that the mode energy equations are approximately independent of the cross mode coherences, and that cross mode coherences and mode energy can evolve over very similar range scales. The decay of cross mode coherence depends on the relative mode phase randomization caused by coupling and adiabatic effects, each of which can be quantified by the theory. This behavior has a dramatic effect on the acoustic field second moments like mean intensity. Comparing estimates of the coherence matrix and mean intensity from Monte Carlo simulation, and the transport equations, good agreement is demonstrated for a 100-Hz deep-water example.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1121/1.3158818DOI Listing
September 2009

Modal processing for acoustic communications in shallow water experiment.

J Acoust Soc Am 2008 Sep;124(3):EL177-81

Acoustical array data from the Shallow Water Acoustics experiment was processed to show the feasibility of broadband mode decomposition as a preprocessing method to reduce the effective channel delay spread and concentrate received signal energy in a small number of independent channels. The data were collected by a vertical array designed at the Woods Hole Oceanographic Institution. Phase-shift Keying (PSK) m-sequence modulated signals with different carrier frequencies were transmitted at a distance 19.2 km from the array. Even during a strong internal waves activity a low bit error rate was achieved.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1121/1.2960954DOI Listing
September 2008

Underwater tunable organ-pipe sound source.

J Acoust Soc Am 2007 Aug;122(2):777-85

Webb Research Corporation, East Falmouth, Massachusetts 02536, USA.

A highly efficient frequency-controlled sound source based on a tunable high-Q underwater acoustic resonator is described. The required spectrum width was achieved by transmitting a linear frequency-modulated signal and simultaneously tuning the resonance frequency, keeping the sound source in resonance at the instantaneous frequency of the signal transmitted. Such sound sources have applications in ocean-acoustic tomography and deep-penetration seismic tomography. Mathematical analysis and numerical simulation show the Helmholtz resonator's ability for instant resonant frequency switching and quick adjustment of its resonant frequency to the instantaneous frequency signal. The concept of a quick frequency adjustment filter is considered. The discussion includes the simplest lumped resonant source as well as the complicated distributed system of a tunable organ pipe. A numerical model of the tunable organ pipe is shown to have a form similar to a transmission line segment. This provides a general form for the principal results, which can be applied to tunable resonators of a different physical nature. The numerical simulation shows that the "state-switched" concept also works in the high-Q tunable organ pipe, and the speed of frequency sweeping in a high-Q tunable organ pipe is analyzed. The simulation results were applied to a projector design for ocean-acoustic tomography.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1121/1.2751268DOI Listing
August 2007

High-attenuation mucus plugs on MDCT in a child with cystic fibrosis: potential cause and differential diagnosis.

Pediatr Radiol 2007 Jun 24;37(6):592-5. Epub 2007 Apr 24.

Indiana University Medical School, Indianapolis, IN, USA.

High-attenuation mucus plugging is a rare finding in both adults and children. When it occurs, the field of differential diagnoses is typically quite small and includes acute hemorrhage, aspiration of radiodense material, and allergic bronchopulmonary aspergillosis (ABPA). The last of these three diagnoses is the most difficult to make, although ABPA is more commonly seen in children with cystic fibrosis (CF) or asthma. ABPA is radiographically characterized by recurrent mucus plugging, atelectasis, and central bronchiectasis. Thus far, high-attenuation mucus plugs have only been reported in adults. We report a rare case of a child with CF who had high-attenuation mucus plugs and atelectasis that raised the possibility of ABPA. We discuss the differential diagnoses of this finding and the role of multidetector CT in these children.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00247-007-0471-8DOI Listing
June 2007