Assessment of Prostate and Bladder Cancer Genomic Biomarkers Using Artificial Intelligence: a Systematic Review.

PURPOSE OF REVIEW: The aim of the systematic review is to assess AI's capabilities in the genetics of prostate cancer (PCa) and bladder cancer (BCa) to evaluate target groups for such analysis as well as to assess its prospects in daily practice. RECENT FINDINGS: In total, our analysis included 27 articles: 10 articles have reported on PCa and 17 on BCa, respectively. The AI algorithms added clinical value and demonstrated promising results in several fields, including cancer detection, assessment of cancer development risk, risk stratification in terms of survival and relapse, and prediction of response to a specific therapy. Besides clinical applications, genetic analysis aided by the AI shed light on the basic urologic cancer biology. We believe, our results of the AI application to the analysis of PCa, BCa data sets will help to identify new targets for urological cancer therapy. The integration of AI in genomic research for screening and clinical applications will evolve with time to help personalizing chemotherapy, prediction of survival and relapse, aid treatment strategies such as reducing frequency of diagnostic cystoscopies, and clinical decision support, e.g., by predicting immunotherapy response. These factors will ultimately lead to personalized and precision medicine thereby improving patient outcomes.

A 10-year renaissance of en bloc resection of bladder tumors (ERBT): Are we approaching the peak or is it back to the trough?

BACKGROUND: The number of studies suggesting that en bloc resection of bladder tumor (ERBT) is superior to transurethral resection of bladder tumor (TURBT) for non-muscle-invasive bladder cancer (NMIBC) management is growing. The aim of this review is to discuss the features of these procedures and to determine the prospects of en bloc in NMIBC management. MATERIALS AND METHODS: We conducted a literature search using two databases (Medline and Scopus) and included any research which reported ERBT outcomes. RESULTS: The lasers with minimal tissue penetration depth are becoming the main tool for ERBT. Unfortunately, most of the systematic reviews continue to be characterized by high heterogeneity. However, recent studies indicate that ERBT may have the edge when it comes to the detrusor muscle rate and the quality of the histological specimen. ERBT may favor in terms of in-field relapse, but its rate in the studies varies greatly. As for out-field relapse-free survival, the data are still lacking. The strongest evidence supports that ERBT is superior to TURBT in complications rate (bladder perforation). ERBT is feasible irrespective to tumor size and location. CONCLUSIONS: ERBT has gained in momentum with the increasingly widespread use of this kind of laser surgery. The introduction of novel sources (TFL and Thulium:YAG pulsed laser) will definitely affect how the field develops and will result in further improvements in safety and precision. The latest trials make us more certain in our belief that ERBT will be beneficial in terms of histological specimen quality, relapse rate and complications rate.

Thulium fiber laser vs Ho:YAG in RIRS: a prospective randomized clinical trial assessing the efficacy of lasers and different fiber diameters (150 µm and 200 µm).

INTRODUCTION: The aims of the study: (1) to compare the Super Pulse Thulium Fiber Laser (SP TFL) and the holmium: yttrium-aluminium-garnet (Ho:YAG) lasers in retrograde intrarenal surgery (RIRS); (2) to compare the efficacy of SP TFL laser fibers of different diameters (150 µm and 200 µm). METHODS: A prospective randomized single-blinded trial was conducted. Patients with stones from 10 to 20 mm were randomly assigned RIRS in three groups: (1) SP TFL (NTO IRE-Polus, Russia) with fiber diameter of 150 µm; (2) SP TFL with 200-µm fiber; and (3) Ho:YAG (Lumenis, USA) with 200-µm fiber. RESULTS: Ninety-six patients with kidney stones were randomized to undergo RIRS with SP TFL using a 150-µm fiber (34 patients) and a 200-µm fiber (32 patients) and RIRS with Ho:YAG (30 patients). The median laser on time (LOT) in the 200-µm SP TFL group was 9.2 (6.2-14.6) min, in 150-µm SP TFL-11.4 (7.7-14.9) min (p = 0.390), in Ho:YAG-14.1 (10.8-18.1) min (p = 0.021). The total energy consumed in 200-µm SP TFL was 8.4 (5.8-15.2) kJ; 150-µm SP TFL - 10.8 (7.3-13.5) kJ (p = 0.626) and in Ho:YAG-15.2 (11.1-25.3) kJ (p = 0.005). CONCLUSIONS: Irrespective of the density, RIRS with SP TFL laser has proven to be both a safe and effective procedure. Whilst the introduction of smaller fibers may have the potential to reduce the duration of surgery, SP TFL results in a reduction in the LOT and total energy for stone ablation in RIRS compared with Ho:YAG.

Comparison of EEP and TURP long-term outcomes: systematic review and meta-analysis.

OBJECTIVE: To compare long-term reoperation rate and functional outcomes between EEP (endoscopic enucleation of the prostate) and TURP (transurethral resection of the prostate). EVIDENCE ACQUISITION: A systematic literature review of Medline, Scopus, and Web of Science was conducted with primary outcome assessed being reoperation rate and secondary outcomes after a long term (> 3 years) being functional outcomes or related values (prostate volume, PSA level, etc.). EVIDENCE SYNTHESIS: Five studies were found with long-term follow-up 4-7 years. EEP reoperation rate ranged from 0 to 1.27%, while from 1.7 to 17.6% for TURP. Meta-analysis showed significantly lower OR for EEP, 0.27 (95% CI 0.24-0.31), with notable homogeneity of the results, I2 = 0%. Long-term Qmax and IPSS were significantly better for EEP. Qmax pooled mean difference was 1.79 (95% CI 1.72-1.86) ml/s with a high concordance among the studies, I2 = 0%. IPSS mean difference -1.24 (95% CI - 1.28 to - 1.2) points, I2 = 57% but QoL did not differ, with mean difference being 0.01 (95% CI - 0.02 to 0.04), I2 = 0%. IIEF-5 score was also significantly better for EEP, mean difference 1.08 (95% CI 1.03-1.13), but heterogeneity was high, I2 = 70%. PSA level and prostate volume were only reported in one study and favored EEP slightly yet statistically significant. CONCLUSION: EEP had a significantly lower reoperation rate and better functional outcomes (Qmax and IPSS) at long term compared with TURP. It may also be beneficial in terms of IIEF-5, PVR, and PSA level.

Determination of Greenhouse Gas Concentrations from the 16U CubeSat Spacecraft Using Fourier Transform Infrared Spectroscopy.

Greenhouse gases absorb the Earth's thermal radiation and partially return it to the Earth's surface. When accumulated in the atmosphere, greenhouse gases lead to an increase in the average global air temperature and, as a result, climate change. In this paper, an approach to measuring CO2 and CH4 concentrations using Fourier transform infrared spectroscopy (FTIR) is proposed. An FTIR spectrometer mockup, operating in the wavelength range from 1.0 to 1.7 µm with a spectral resolution of 10 cm-1, is described. The results of CO2 and CH4 observations throughout a day in urban conditions are presented. A low-resolution FTIR spectrometer for the 16U CubeSat spacecraft is described. The FTIR spectrometer has a 2.0-2.4 µm spectral range for CO2 and CH4 bands, a 0.75-0.80 µm range for reference O2 bands, an input field of view of 10-2 rad and a spectral resolution of 2 cm-1. The capabilities of the 16U CubeSat spacecraft for remote sensing of greenhouse gas emissions using a developed FTIR spectrometer are discussed. The design of a 16U CubeSat spacecraft equipped with a compact, low-resolution FTIR spectrometer is presented.

A systematic review and meta-analysis of placebo effect in clinical trials on chronic prostatitis/chronic pelvic pain syndrome.

BACKGROUND: It is a common practice to control efficacy of pharmacological treatment with a placebo group. However, placebo itself may affect subjective and even objective results. The purpose of this study was to evaluate the placebo effect on symptoms of CP/CPPS to improve future clinical trials. METHODS: A search at three databases (Scopus, MEDLINE, and Web of Science) was conducted to identify double-blind placebo-controlled clinical trials on the treatment of CP/CPPS published until April 2021. The primary outcome - National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) score. SECONDARY OUTCOMES: Qmax, PVR, IPSS, and prostate volume. RESULTS: A total of 3502 studies were identified. Placebo arms of 42 articles (5512 patients, median 31 patients) were included in the systematic review. Systematic review identified positive changes in the primary endpoint, meta-analysis of 10 articles found that NIH-CPSI total score results were significantly influenced by placebo, mean difference -4.2 (95% confidence interval [CI]: -6.31, -2.09). Mean difference of NIH-CPSI pain domain was -2.31 (95% CI: -3.4, -1.21), urinary domain -1.12 (95% CI: -1.62, -0.62), quality of life domain -1.67 (95% CI: -2.38, -0.96); p < 0.001 for all. In case of the objective indicator - Qmax, there were three articles included in the meta-analysis. Qmax mean change from baseline was 0.68 (95% CI: -0.85, 2.22, p = 0.38). Systematic review showed no significant changes in pain, measured by VAS or other scores, IPSS and PVR. CONCLUSIONS: Placebo significantly affected the subjective parameters (NIH-CPSI) and limitedly affected various other measurements of pain (visual analog scale, McGill pain questionnaire). There was no long-term effect on IPSS and objective measurements (Qmax, PVR). This study can be used in further clinical trials to develop general rules of CPPS treatment assessment.

Additional Workups Recommended During Preoperative Breast MRI: Methods to Gain Efficiency and Limit Confusion.

BACKGROUND: Preoperative breast MRI is indicated for staging but can lead to complex imaging workups. This study reviewed imaging recommendations made on preoperative MRI exams, to simplify management approaches for patients with newly diagnosed breast cancer. METHODS: This retrospective single-institution review was restricted to women with breast cancer who underwent staging MRI. Additional breast lesions, separate from index tumors, recommended for additional workup or surveillance were assessed to see which were detected and which characteristics predicted success in detection. Univariate mixed-effects logistic modeling predicted the likelihood of finding lesions using MRI-directed ultrasound (US), with odds ratios reported. Tests were two-sided, with a p value lower than 0.05 considered significant. RESULTS: In this study, 534 (39.6%) patients had recommendations for additional workup after preoperative MRI. MRI detected additional malignancy in 178 patients (33.3%). Half of the 66 patients who refused an additional workup and opted for mastectomy had additional malignancies at mastectomy. MRI-directed US was 14 times more likely to detect masses than nonmass enhancement (NME) (p < 0.001). NME was detected on US in only 16% of cases, with one third of subsequent biopsy results considered discordant. Probably benign assessments were given to 35 patients, with 23% not returning for follow-up evaluation and 7% returning at least 6 months later than recommended. CONCLUSION: Use of preoperative breast MRI has increased. Although it can add value, institutions should establish indications and expectations to prevent unnecessary workups. Limiting MRI-directed US to masses, avoiding probably benign assessments, and consulting with patients after MRI but prior to workups can prevent unnecessary exams and confusion.

Randomized prospective trial of the severity of irritative symptoms after HoLEP vs ThuFLEP.

PURPOSE: To compare the short-term postoperative functional outcomes and severity of irritative symptoms following holmium and thulium fiber laser enucleation (HoLEP and ThuFLEP). METHODS: This prospective randomized single-blinded study was performed in accordance with CONSORT. The inclusion criteria were IPSS > 20 or Qmax < 10 ml/s. Patients were randomized between HoLEP and ThuFLEP. Demographics, objective data (PSA, prostate volume, etc.), data on urinary and sexual function (IPSS, IIEF, QoL, QUID, Qmax, ICIQ-MLUTS) were collected. Detailed perioperative information and postoperative data on functional outcomes at 1, 2, 3, 4, 6, 8, 10, 12 weeks and 6 months were collected. RESULTS: Data on 163 participants were included (77-HoLEP, 86-ThuFLEP). No differences were found in surgery duration; number of postoperative complications (Clavien-Dindo I-III), catheterization time and hospital stay. Functional outcomes up to 6 months didn't differ between the groups (IPPS, IIEF, QoL, QUID, ICIQ-MLUTS, Qmax, p > 0.05). Total ICIQ-MLUTS, bother and voiding scores at 1 and 3 months significantly increased compared with the baseline in both groups (p < 0.05). No difference between the groups were observed. In HoLEP the SUI series rate was 1.3% and 1.3% after 3 and 6 months following the procedure; in ThuFLEP: it was 3.5% and 2.3% respectively (p = 0.35 and p = 0.54). CONCLUSION: The preliminary results of the study showed no apparent differences in functional outcomes (IPSS, Qmax), rate of SUI or irritative symptoms. Both ThuFLEP and HoLEP are efficient ways of treating benign prostatic obstruction. Both surgeries are comparable in terms of duration and postoperative complication rates.

EAU, AUA and NICE Guidelines on Surgical and Minimally Invasive Treatment of Benign Prostate Hyperplasia: A Critical Appraisal of the Guidelines Using the AGREE-II Tool.

OBJECTIVE: To critically appraise the methodological rigour of the clinical practice guidelines (CPGs) vis-à-vis BPH surgery as used by specialist research associations in the US, Europe and UK, and to compare whether the guidelines cover all or only some of the available treatments. METHODS: The current guidelines issued by the EUA, AUA and NICE associations have been analyzed by 4 appraisers using the AGREE-II instrument. We also compared the recommendations given in the guidelines for surgical and minimally invasive treatment to find out which of these CPGs include most of the available treatment options. RESULTS: According to the AGREE II tool, the median scores of domains were: domain 1 scope and purpose 66.7%, domain 2 stakeholder involvement 50.0%, domain 3 rigor of development 65.1%, domain 4 clarity of presentation 80.6%, domain 5 applicability 33.3%, domain 6 editorial independence 72.9%. The overall assessment according to AGREE II is 83.3%. The NICE guideline scored highest on 5 out of 6 domains and the highest overall assessment score (91.6%). The EAU guideline scored lowest on 4 out of 6 domains and has the lowest overall assessment score (79.1%). CONCLUSIONS: The analyzed CPGs comprehensively highlight the minimally invasive and surgical treatment options for BPH. According to the AGREE II tool, the domains for clarity of presentation and editorial independence received the highest scores. The stakeholder involvement and applicability domains were ranked as the lowest. Improving the CPG in these domains may help to improve the clinical utility and applicability of CPGs.

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

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.

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

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, I2 = 98% and "per patient", OR = 1.83 (95% CI 1.51; 2.21), p < 0.0001, I2 = 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.

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

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).

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

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) mm3 . 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) mm3 /min, energy for ablation of 1 mm3 was 5.6 (3-9.9) J/mm3 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.

Underwater ultra-low frequency seismic source.

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.

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

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.

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

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.

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

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.

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

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.

Description of Transfer Processes in a Locally Nonequilibrium Medium.

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.

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

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.