Convection Of Water Research Articles

Preliminary results of a national multicenter study on the treatment of LUTS secondary to benign prostatic hyperplasia using the Rezūm® steam system

Introduction and objectiveRezūm® system is a minimally invasive transurethral therapy that uses convective water vapor energy to ablate prostatic tissue. The objective is to report 1-year functional and security outcomes obtained by using this technique in real clinical practice. Material and methodsProspective study conducted in 5 Spanish hospitals for the treatment of LUTS secondary to BPH using the Rezūm® system. Patients with prostatic medium lobe (ML) and urethral catheter carriers were also included. Pre- and post-operative data were collected using IPSS, IIEF-5 and QoL questionnaires, flowmetry and post-void residual volume. Complications and retreatment rate at one-year follow-up were also reported. Results137 patients, including 64 with ML and 10 patients with urinary retention were treated. Median prostate volume was 50 cm3 (15−131). At 3 months follow-up, significant improvement was observed in IPSS (−6.37 points), Qmax (+4.95 mL/s) and QoL (−1.29); and was maintained until 12 months: −10.78 points, +4.62 mL/s and −2.73 respectively (p < 0.001). No significant changes were observed in the sexual sphere. All complications were mild (≤ Clavien II). Retreatment rate at one year was 4%. ConclusionShort-term results of this technique are promising, showing improvement in terms of functional outcomes, with no impact on the sexual sphere or complications. Longer term follow-up should include treatment durability and comparison to standard BPH treatments.

Dynamic modeling of a water tube boiler

AbstractThe present work aims to develop an integrated heat transfer and hydrodynamic model for the study of boiler dynamics in fluctuating load conditions. A transient heat transfer model has been developed to estimate water side heat transfer and it is directly integrated with the hydrodynamic model. Two independent natural circulation circuits for furnace water wall and convection tube bank have been considered due to differences in heat transfer, dryness fraction, and void fraction. The transient heat transfer model calculates the heat transfer and water wall temperature of the various sections to calculate total gas side heat transfer, gas temperature profile, and waterside heat transfer in the furnace water wall and convection tube bank. Mass momentum and energy conservation equations are generated for both natural circulation circuits using the estimated value of waterside heat transfer of the transient heat transfer model. These equations are integrated with mass and energy conservation equations for the drum below water level and drum above water level to generate a system of equations to estimate drum pressure and water level fluctuation. This model has been extended for boiler feedback control systems, including the load management and the water level control system.

Symmetry-breaking natural convection of water in an infinite vertical channel maintained at different temperatures

The transition to chaos in natural convection in a water layer between two differentially heated infinite vertical plates is investigated using direct numerical simulation under the Boussinesque approximation. After the primary instability of the base flow in the conduction regime at Rayleigh number Rac ∼ 58,000, a sequence of bifurcations leading to unsteady three-dimensional flow follow, and the flow eventually becomes chaotic at approximately 2Rac. In particular, at 6Rac, the symmetry between the upward flow near the hot wall and the downward flow near the cold wall breaks, and either the upward or downward flow appears with intermittent transition between them. As the Rayleigh number increases, the asymmetry increases and the transition between the upward and downward flows becomes less frequent, and only one of these two flows persists with net flow in one direction.

Onset of double-diffusive convection in water and ester based magnetic nanofluids

The present paper studies the onset of double diffusive convection in water based magentic nanofluids (WMNF) and ester based magnetic nanofluids (EMNF) for a thin horizontal layer. The fluid is heated and salted from below. The effect of three important slip mechanisms viz., Brownian diffusion, thermophoresis and magnetophoresis has been incorporated. The Eigen value problem is solved by the numerical method. The results are presented for rigid-rigid boundaries in the gravity environment. Critical Rayleigh number is determined in terms of the governing non-dimensional parameters like solutal Rayleigh number, solutal Lewis number and nanoparticle concentration Rayleigh number.

Free convection to cool a hot square block by embedding in center of a chamber by nanofluid and magnetohydrodynamic

Hot block is observed in numerous industries and applications that can being an electronic component, solid matrix, battery, etc. In the present 2D simulation, a uniform magnetic field (MHD model) in the x-direction was utilized to affect the free convection of nanofluid water- A l 2 O 3 for aim of improvement and control the heat transfer and flow characterizations. The used geometry consisted of square chamber and hot block embedded in center of square chamber. The walls of the hot block and chamber performed as hot and cold sources led to create buoyancy force. This study investigated for Varity inclined angles of hot block ( 0 < η < 45 ), Rayleigh numbers ( 10 2 < R a < 10 4 ) and Hartmann numbers ( 0 < H a < 40 ) when the volume fraction of suspension was φ = 0.04 . Also, the effects of the mentioned parameters were studied on the streamlines, temperature contours, average Nusselt number. Observations showed that Adding magnetic field increased the heat transfer rate by 200% At low Rayleigh numbers, but it reduced the heat transfer rate 48% At high Rayleigh numbers.

PD45-04 CHANGE IN PROSTATE VOLUME REDUCTION AND SYMPTOMATIC IMPROVEMENT IN MEN TREATED WITH REZUM CONVECTIVE WATER VAPOUR THERMAL THERAPY

You have accessJournal of UrologyCME1 May 2022PD45-04 CHANGE IN PROSTATE VOLUME REDUCTION AND SYMPTOMATIC IMPROVEMENT IN MEN TREATED WITH REZUM CONVECTIVE WATER VAPOUR THERMAL THERAPY Dean Elterman, Katherine Lajkosz, Kevin C. Zorn, Bilal Chughtai, and Naeem Bhojani Dean EltermanDean Elterman More articles by this author , Katherine LajkoszKatherine Lajkosz More articles by this author , Kevin C. ZornKevin C. Zorn More articles by this author , Bilal ChughtaiBilal Chughtai More articles by this author , and Naeem BhojaniNaeem Bhojani More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002613.04AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Rezum, convective water vapour thermal therapy is a minimally invasive, office-based treatment for benign prostatic enlargement (BPE). While studies have demonstrated its efficacy in symptom improvement, its effect on objective measures such as prostate volume reduction is poorly characterized. Herein, we evaluate change in prostate volume and the relationship to improvement in symptom score. METHODS: Quality of life outcomes and prostate volume were assessed as baseline and 12-months post-procedure. Percent change from baseline in outcomes and prostate volume were calculated for each patient. The injection to baseline volume ratio was calculated for each patient. The association between total number of vapour injections and changes in outcomes and prostate volume were evaluated using linear regression models. RESULTS: A total of 49 patients underwent the procedure between April 2019 and September 2020, with a mean of age of 67.8 (SD=9.4), mean baseline volume of 73.2cc (SD 27.9) and mean number of vapour injections was 11.0 (SD 3.5). At 12 months, the mean percent change in prostate volume was -30.2% (SD 29.1), with 45/49 (91.8%) patients overall having reduced volume at 12 months. Within the 45 patients with reduced volume at 12 months, every 10% increase in volume reduction was associated with a 7.5% (95% CI 1.40 to 13.6%, p=0.011) decrease in IPSS score at 12 months. There was no significant association between total number of injections or injection to baseline volume ratio and change in volume. CONCLUSIONS: In this cohort of larger size prostates, we demonstrated a 30% prostate volume reduction at 12-months, with a correlation between greater volume reduction and greater symptomatic improvement. There is no association between more injections or the ratio of injections to prostate volume and change in size, refuting the claim that more injections are better. Source of Funding: Not applicable © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e783 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Dean Elterman More articles by this author Katherine Lajkosz More articles by this author Kevin C. Zorn More articles by this author Bilal Chughtai More articles by this author Naeem Bhojani More articles by this author Expand All Advertisement PDF DownloadLoading ...

MP01-08 CONVECTIVE WATER VAPOR THERMAL THERAPY (CWVTT) IMPROVES NOCTURIA AND SUBJECTIVE SLEEP QUALITY

You have accessJournal of UrologyCME1 May 2022MP01-08 CONVECTIVE WATER VAPOR THERMAL THERAPY (CWVTT) IMPROVES NOCTURIA AND SUBJECTIVE SLEEP QUALITY Aya Bsatee, Gaurav Pahouja, Michael Felice, Hiten D. Patel, and Kevin T. McVary Aya BsateeAya Bsatee More articles by this author , Gaurav PahoujaGaurav Pahouja More articles by this author , Michael FeliceMichael Felice More articles by this author , Hiten D. PatelHiten D. Patel More articles by this author , and Kevin T. McVaryKevin T. McVary More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002513.08AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Nocturia and disrupted sleep are common motivating complaints for men to seek lower urinary tract symptom (LUTS) treatment. We previously reported a cross-sectional and longitudinal association between the bother and severity of LUTS, and the severity of sleep disturbances. Convective water vapor thermal therapy (CWVTT) is a new minimally invasive surgical therapy (MIST) for LUTS. Currently, there is a lack of data examining the relationship between nocturia and disrupted sleep following MIST for LUTS, including CWVTT. In this study, we aimed to assess nocturia and subjective sleep quality in men prior to and following CWVTT treatment. METHODS: Patients who underwent CWVTT between 2018-2021 were eligible for inclusion in the study. Patient demographics, peri-operative data, and clinical outcomes data were extracted. Exclusion criteria included missing pre or post-operative symptom scores, and starting or stopping obstructive sleep apnea (OSA) treatment during the follow-up period. Nocturia was assessed via International Prostate Symptom Score – Nocturia question (IPPS-N). Sleep quality was assessed via Jenkins Sleep Score (JSS). Pre-operative IPSS-N and JSS were compared to early (<60 days) and late (>120) post-operative scores using the Student’s t-tests. Further analysis was also conducted with linear regression. RESULTS: A total of 107 patients qualified for analysis. The median age of patients was 69 years. Approximately 9.3% of the patients had a diagnosis of OSA. In the early postoperative period, there was a significant improvement in IPSS-N (preoperative IPSS-N=3 vs postoperative IPSS-N=2, p=0.003), and JSS (preoperative JSS=9.5 vs postoperative JSS=8, p=0.030) following CWVTT. These results were sustained in the late postoperative period for both IPSS-N (preoperative IPSS-N=3 vs postoperative IPSS-N= 2, p <0.001) and JSS (preoperative JSS=9 vs postoperative JSS=6, p<0.001). On multivariable logistic regression, higher age was associated with improvement in IPSS-N (OR 1.06 [95% CI 1.0-1.14], p=0.04) and lower prostate volume was associated with improvement in JSS (OR -0.07 [95% CI -0.12-(-0.02)], p=0.009). CONCLUSIONS: There is a clinically significant improvement in nocturia and subjective sleep quality following CWVTT. Physiologic mechanisms responsible for a global improvement in sleep beyond simply reduced nocturia deserve further study. Source of Funding: None © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e4 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Aya Bsatee More articles by this author Gaurav Pahouja More articles by this author Michael Felice More articles by this author Hiten D. Patel More articles by this author Kevin T. McVary More articles by this author Expand All Advertisement PDF DownloadLoading ...

Linear and non-linear stability analyses of Rayleigh-Bénard convection in water–copper and water–alloy nanoliquids

In this paper, we perform linear and non-linear stability analyses of Rayleigh-Bénard convection in a horizontal layer of water–copper and water–alloy nanoliquids. The corresponding eigen values for the problems involving the two nanoliquids are obtained and compared. The thermophysical properties of nanoliquids have been modelled as a function of the properties of water as base liquid, copper and alloy as nanoparticles. A non-linear analysis is performed using the energy method. The subcritical instability does not exist. As a limiting case the results of water are discussed with results of previous investigations, and a good agreement is found. The effect of nanoparticles is to destabilise the system. The results are depicted graphically.

Two-stage multichannel liquid–metal cooling system for thermal management of high-heat-flux-density chip array

A two-stage multichannel liquid–metal cooling system for a high-heat-flux-density chip array is investigated in this study. This system exhibits high cooling performance, low cost, excellent temperature uniformity, and high reliability. The first stage, which comprises a multichannel liquid metal convection subsystem, is implemented in the high-heat-flux-density chip area to achieve high cooling performance. The second stage, which comprises a water convection subsystem, is utilized in the low-heat-flux-density area to effectively reduce the system cost. Because the liquid–metal loops are equipped with independent electromagnetic pumps for each chip, the chip temperature can be conveniently adjusted, thereby guaranteeing good temperature uniformity. The experimental results show that the proposed liquid–metal cooling system can accommodate a heat flux of 50–200 W/cm2 with a convective heat transfer coefficient exceeding 20 000 W/(m2·K). Moreover, the flow of liquid metal can be continuously adjusted by varying the input current of the electromagnetic pump to ensure a chip array temperature uniformity of approximately 1 °C. The proposed liquid–metal cooling system can serve as a high-performance solution for the thermal management of high-heat-flux-density chip arrays in data centers.

Efficacy, Safety, and Sexual Dysfunction Outcomes of Water Vapor Thermal Therapy (Rezum) in Patients with Lower Urinary Tract Symptoms Secondary to Benign Prostatic Hyperplasia: An Updated Systematic Review

ABSTRACT Introduction Benign prostatic hyperplasia (BPH) is an exceedingly common condition affecting a large portion of men, often leading to progressive development of lower urinary tract symptoms (LUTS). Water vapor thermal therapy, also known as The Rezum System (Boston Scientific Corporation, Marlborough, MA, USA), is a novel, minimally invasive surgical technology used to treat LUTS secondary to BPH. Rezum utilizes convective radiofrequency water vapor to ablate the lateral and median lobes of the prostate, decreasing prostate size and improving LUTS. Despite its FDA approval in 2015, there is a sparsity of studies, particularly systematic reviews, describing outcomes. Objective To evaluate the latest efficacy and safety profile of Rezum in patients with LUTS secondary to BPH. Methods PubMed/MEDLINE and The Cochrane Library databases were systematically searched, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, for relevant articles in the English language till June 1, 2021. Search strategy included the following terms: “water vapor thermal therapy” OR “Rezum” OR “convective water vapor thermal therapy” OR “convective radiofrequency water vapor thermal therapy”. Randomized and non-randomized studies that evaluated urinary outcomes and/or adverse events of Rezum in patients with LUTS secondary to BPH were deemed eligible. Results 16 studies (N=1,703), published in 22 papers, met the inclusion criteria and were included in the systematic review. Of the 16 studies, one was an RCT, five were prospective studies, eight were retrospective studies, and two were case series. When compared to baseline, international prostate symptom score (IPSS), quality of life (QoL), and maximum urinary flow rate (Qmax) significantly improved as early as 1-month post-treatment and remained durable for up to 5 years. Significant percent improvements from baseline to 3-month in IPSS, QoL, and Qmax ranged between 39 to 86% (median: 55%), 45 to 86% (median: 65%), and 32 to 74% (median: 62%), respectively. Most adverse events were transient and non-serious and occurred in between 0 to 83% of patients (median: 47%), with dysuria, urinary retention, urinary tract infection, and hematuria being the most common. Five studies reported no de novo erectile dysfunction, while three studies reported rates between 2.4 to 3.1%. One study reported de novo anejaculation rate of 2.9% while another study reported it at 10.8%. Three studies reported decreases in ejaculatory volume rates between 2.9 to 10.8%, one study reported retrograde ejaculation rate at 3.1%, and one study reported painful ejaculation rate at 1.6%. The surgical retreatment rate ranged between 1.0 to 3.1% at 1 year and between 4.4% and 7.5% at 5 years (Table 1). Conclusions Rezum effectively improved LUTS secondary to BPH with durable outcomes at 5 years post-operatively. Real-world outcomes showed that non-serious adverse events were considerable, but transient, and with low rates of sexual dysfunction. In light of these findings, Rezum remains an attractive surgical modality for men with LUTS secondary to BPH. Disclosure No

Numerical study on influence of titling position and density extremum on convection in a porous cavity with sinusoidal heating

The aspiration of the present problem is to investigate numerically the 2D unsteady buoyancy convection of cold water near its highest density value in an inclined square porous enclosed space. Left sidewall temperature varies in sinusoidal manner whereas the opposing right sidewall is sustained with constant lower temperature. The walls along x axis and parallel to x axis are kept in adiabatic condition. The range of angle of inclination is considered from 0 degree to 90 degree. The finite volume method (FVM) was applied to portray all mathematical equations. The special outcome of inclination angle, Darcy number, maximum density parameter and porosity are obtained in the present study with the use of Brinkmann–Forchheimer extended Darcy model. The change in the angle of inclination is noteworthy in the structure and direction of the flow of the fluid. The bicellular structure of the fluid is identified because of the higher density effect.

A new convective parameterization applied to Jupiter: Implications for water abundance near the 24°N region

Jupiter’s atmosphere features a variety of clouds that are formed from the interplay of chemistry and atmospheric dynamics, from the deep red color of the Great Red Spot to the high altitude white ammonia clouds present in the zones (bright bands in Jupiter’s atmosphere). Beneath these upper level clouds, water condensation occurs, and sporadically leads to the formation of towering convective storms, driven by the release of large amounts of latent heat. These storms result in a widespread disruption of the cloud and dynamical structure of the atmosphere at the latitude where they form, making the study of these events paramount in understanding the dynamics at depth, and the role of water in the jovian atmosphere. In this work, we use the Explicit Planetary hybrid-Isentropic Coordinate (EPIC) General Circulation Model (GCM) to study the jovian atmosphere, with a focus on moist convective storm formation from water condensation. We present the addition of a sub-grid scale moist convective module to model convective water cloud formation. We focus on the 24°N latitude, the location of a high speed jetstream, where convective upwellings have been observed every 4–5 years. We find that the potential of convection, and vertical mass and energy flux of the atmosphere is strongly correlated with the amount of water, and we determine an upper limit of the amount of water in the region surrounding the jet as twice the solar [O/H] ratio.

Chaotic phenomena of natural convection for water in a V-shaped enclosure

The changes from steady-state to chaotic natural convection in a V-shaped differentially heated enclosure have been studied numerically because of their importance in nature, such as in a river or lake. The finite volume method (FVM) is applied to simulate the Navier-Stokes and Energy equations with proper boundary conditions. The working fluid is considered water with the Prandtl number, Pr = 7.0 for various Rayleigh numbers ranging from Ra = 100 to 106 with a fixed aspect ratio, A = 0.5. A group of bifurcations in the transitional flow is investigated, including a Pitchfork and a Hopf bifurcations. The occurrence of Pitchfork bifurcation happens between Ra = 1.3 × 104 and 1.4 × 104 and of Hopf bifurcation happens between Ra = 1.6 × 105 and 1.7 × 105. Moreover, another bifurcation occurs between Ra = 2.6 × 105 and 2.7 × 105 for the changeover from intervallic state to chaotic state. Power spectral density of temperature time series, phase space trajectories, and the largest Lyapunov exponents of the unsteady chaotic flows are also investigated. Additionally, heat and mass transfer are measured and explained elaborately with physical significance.

Large, Multi-Center, Prospective Registry of Rezūm Water Vapor Therapy for Benign Prostatic Hyperplasia

ObjectiveTo illustrate the role of Rezūm convective water vapor ablation for treatment of lower urinary tract symptoms secondary to Benign prostatic hyperplasia. MethodsA prospective registry was established for Rezūm therapy in Canada at two high-volume centers. All patients had baseline medical and Benign prostatic hyperplasia history documented, along with uroflowmetry and validated questionnaires up to 12 months post-surgery. Results229 patients (mean age 67.3 years), including 83 with prostate volumes ≥80 mL, were treated from April 2019 to December 2020. The mean prostate volume was 71.5 mL (range 20-160 mL) and 55% had a median lobe. The mean number of injections was 11 (range: 4-28) and mean procedural length was 4.8 minutes (range: 1.5-14). The mean duration of postprocedure catheterization was 9.8 days. International Prostate Symptom Scores improved from baseline by 29%, 53%, and 59% at 1, 3, and 12 months, respectively. International Prostate Symptom Scores quality of life improved from baseline by 30%, 50%, and 67% at 1, 3, and 12 months, respectively. Qmax improved by 60% at 3 months and 74% at 12 months. Post-void residual volume improved by 51% and 61% at 3 and 12 months, respectively. No statistically significant changes were seen in International Index of Erectile Function-15 or Male Sexual Health Questionnaire for Ejaculatory Dysfunction scores. No Clavien-Dindo events ≥Grade III occurred. ConclusionRezūm therapy is a safe, effective, and quick outpatient procedure for prostate glands over a wide range of volumes. Clinically significant improvements are seen in all validated questionnaires. Objective maximum flow measures improved, while erectile and ejaculatory function remains preserved.

A0724 - Change in prostate volume reduction and symptomatic improvement in men treated with Rezum convective water vapour thermal therapy

A0724 - Change in prostate volume reduction and symptomatic improvement in men treated with Rezum convective water vapour thermal therapy

A case study on the impact of severe convective storms on the water vapor mixing ratio in the lower mid-latitude stratosphere observed in 2019 over Europe

Abstract. Extreme convective events in the troposphere not only have immediate impacts on the surface, but they can also influence the dynamics and composition of the lower stratosphere (LS). One major impact is the moistening of the LS by overshooting convection. This effect plays a crucial role in climate feedback, as small changes of water vapor in the upper troposphere and lower stratosphere (UTLS) have a large impact on the radiative budget of the atmosphere. In this case study, we investigate water vapor injections into the LS by two consecutive convective events in the European mid-latitudes within the framework of the MOSES (Modular Observation Solutions for Earth Systems) measurement campaign during the early summer of 2019. Using balloon-borne instruments, measurements of convective water vapor injection into the stratosphere were performed. Such measurements with a high vertical resolution are rare. The magnitude of the stratospheric water vapor reached up to 12.1 ppmv (parts per million by volume), with an estimated background value of 5 ppmv. Hence, the water vapor enhancement reported here is of the same order of magnitude as earlier reports of water vapor injection by convective overshooting over North America. However, the overshooting took place in the extratropical stratosphere over Europe and has a stronger impact on long-term water vapor mixing ratios in the stratosphere compared to the monsoon-influenced region in North America. At the altitude of the measured injection, a sharp drop in a local ozone enhancement peak makes the observed composition of air very unique with high ozone up to 650 ppbv (parts per billion by volume) and high water vapor up to 12.1 ppmv. ERA-Interim does not show any signal of the convective overshoot, the water vapor values measured by the Microwave Limb Sounder (MLS) in the LS are lower than the in situ observations, and the ERA5 overestimated water vapor mixing ratios. Backward trajectories of the measured injected air masses reveal that the moistening of the LS took place several hours before the balloon launch. This is in good agreement with the reanalyses, which shows a strong change in the structure of isotherms and a sudden and short-lived increase in potential vorticity at the altitude and location of the trajectory. Similarly, satellite data show low cloud-top brightness temperatures during the overshooting event, which indicates an elevated cloud top height.

Convection of water vapour in snowpacks

This paper studies numerically the convection of water vapour in snowpacks using an Eulerian–Eulerian two-phase approach. The convective water vapour transport in snow and its effects on snow density are often invoked to explain observed density profiles, e.g. of thin Arctic snow covers, but this process has never been numerically simulated and analysed in a systematic manner. Here, the impact of convection on the thermal and phase change regimes as a function of different snowpack depths, thermal boundary conditions and Rayleigh numbers is analysed. We find considerable impact of natural convection on the snow density distribution with a layer of significantly lower density at the bottom of the snowpack and a layer of higher density located higher in the snowpack or at the surface. We find that emergent heterogeneity in the snow porosity results in a feedback effect on the spatial organization of convection cells causing their horizontal displacement. Regions where the snowpack is most impacted by phase changes are found to be horizontally extended and vertically thin, ‘pancake’-like layers at the top and bottom of the snowpack. We further demonstrate that among the parameters important for natural convection, the snowpack depth has the strongest influence on the heat and mass transfer. Despite our simplifying assumptions, our study represents a significant improvement over the state of the art and a first step to accurately simulate snowpack dynamics in diverse regions of the cryosphere.

Bioheat Transfer Basis of Human Thermoregulation: Principles and Applications.

Thermoregulation is a process that is essential to the maintenance of life for all warm-blooded mammalian and avian species. It sustains a constant core body temperature in the face of a wide array of environmental thermal conditions and intensity of physical activities that generate internal heat. A primary component of thermoregulatory function is the movement of heat between the body core and the surface via the circulation of blood. The peripheral vasculature acts as a forced convection heat exchanger between blood and local peripheral tissues throughout the body enabling heat to be convected to the skin surface where is may be transferred to and from the environment via conduction, convection, radiation, and/or evaporation of water as local conditions dictate. Humans have evolved a particular vascular structure in glabrous (hairless) skin that is especially well suited for heat exchange. These vessels are called arteriovenous anastomoses (AVAs) and can vasodilate to large diameters and accommodate high flow rates. We report herein a new technology based on a physiological principle that enables simple and safe access to the thermoregulatory control system to allow manipulation of thermoregulatory function. The technology operates by applying a small amount of heating local to control tissue on the body surface overlying the cerebral spine that upregulates AVA perfusion. Under this action, heat exchangers can be applied to glabrous skin, preferably on the palms and soles, to alter the temperature of elevated blood flow prior to its return to the core. Therapeutic and prophylactic applications are discussed.

Resultados preliminares de un trabajo multicéntrico a nivel nacional para el tratamiento de STUI secundario a hiperplasia benigna de próstata mediante el sistema con vapor de agua Rezūm®

Introduction and objectiveRezūm® system is a minimally invasive transurethral therapy that uses convective water vapor energy to ablate prostatic tissue. The objective is to report 1-year functional and security outcomes obtained by using this technique in real clinical practice. Material and methodsProspective study conducted in 5 Spanish hospitals for the treatment of LUTS secondary to BPH using the Rezūm® system. Patients with prostatic medium lobe (ML) and urethral catheter carriers were also included. Pre- and post-operative data were collected using IPSS, IIEF-5 and QoL questionnaires, flowmetry and post-void residual volume. Complications and retreatment rate at one-year follow-up were also reported. Results137 patients, including 64 with ML and 10 patients with urinary retention were treated. Median prostate volume was 50cm3 (15-131). At 3 months follow-up, significant improvement was observed in IPSS (−6,37 points), Qmax (+4,95mL/s) and QoL (−1,29); and was maintained until 12 months: −10,78 points,+4,62mL/s and −2,73 respectively (p<0.001). No significant changes were observed in the sexual sphere. All complications were mild (≤Clavien II). Retreatment rate at one year was 4%. ConclusionShort-term results of this technique are promising, showing improvement in terms of functional outcomes, with no impact on the sexual sphere or complications. Longer term follow-up should include treatment durability and comparison to standard BPH treatments.

NUMERICAL SIMULATION ON NATURAL CONVECTION AND HEAT TRANSFER OF SUPERCRITICAL WATER IN A SIDEWALL HEATED CYLINDER

In some reactors related to supercritical water technology, such as supercritical water gasification, natural convection is a factor to be considered because of the high thermal compressibility of supercritical water. In this paper, a numerical method is applied to analyze the natural convection and heat transfer characteristics of supercritical water in a sidewall heated cylinder. In order to match the actual situation, an inlet and an outlet are added to the bottom and the top of the cylinder, respectively. The quasi-DNS method is used for numerical simulation, and the thermodynamic properties of supercritical water are calculated by IAPWS-IF97 equations. The flow structure and temperature distribution inside the cylinder are analyzed, and it is found that the flow boundary layer state will affect wall temperature and heat transfer. A heat transfer correlation of supercritical water natural convection is proposed. The Nusselt number has a power relationship with the Rayleigh number with an exponent 0.248, and the average Nusselt number with turbulent boundary layer will be 21.8% higher than that with laminar boundary layer under the present working conditions. Finally, factors affecting wall heat transfer are discussed according to the findings.