Momentum transport and torque scaling in Taylor-Couette flow from an analogy with turbulent convection

We generalize an analogy between rotating and stratified shear flows. This analogy is summarized in Table 1. We use this analogy in the unstable case (centrifugally unstable flow v.s. convection) to compute the torque in Taylor-Couette configuration, as a function of the Reynolds number. At low Reynolds numbers, when most of the dissipation comes from the mean flow, we predict that the non-dimensional torque $G=T/\nu^2L$, where $L$ is the cylinder length, scales with Reynolds number $R$ and gap width $\eta$, $G=1.46 \eta^{3/2} (1-\eta)^{-7/4}R^{3/2}$. At larger Reynolds number, velocity fluctuations become non-negligible in the dissipation. In these regimes, there is no exact power law dependence the torque versus Reynolds. Instead, we obtain logarithmic corrections to the classical ultra-hard (exponent 2) regimes: $$G=0.50\frac{\eta^{2}}{(1-\eta)^{3/2}}\frac{R^{2}}{\ln[\eta^2(1-\eta)R^ 2/10^4]^{3/2}}.$$ These predictions are found to be in excellent agreement with available experimental data. Predictions for scaling of velocity fluctuations are also provided.Comment: revTex, 6 Figure

In search of a universal and objective method to assess facial aging: The new face objective photo-numerical assessment scale

Most patients who undergo cosmetic rejuvenation treatment hope to appear younger and healthier. Although a number of scales have been put forward to assess facial aging, to date none has focused on predicting patients’ age. The purpose of our study was to validate a more complete version of the face - Objective assessment scale previously developed by the authors. Since patients with a photo-damaged skin can look older than others we created a new sub-scale: the facial photo-aging scale, in order to provide a more comprehensive method for the overall assessment of facial aging. The Rasch model was used as part of the validation process. We assigned a score to each patient based on the scales we have developed. The correlation between a patient's actual age and the obtained scores was analyzed; we also analyzed the inter-rater reliability and test-retest reliability. All the scales exceeded criteria for acceptability, reliability and validity. The facial aging scale we have developed may prove to be a valuable tool to assess patients before and after facial rejuvenation treatment or surgery, as well as for clinical research in the field of facial skin regeneration

Proposal of a Noninvasive Method to Reduce Injection-Related Bruising in Aesthetic Medicine: Transillumination

Background: Hyaluronic acid (HA) injections involve a risk of vascular complications. Transillumination (TL) is a noninvasive technique that appears to allow preliminary detection of superficial vascular structures of the face to avoid intravascular HA injection. The purpose of our study was to test the efficacy of TL in terms of its sensitivity to locate vessels in the areas undergoing treatment and to reduce post-injection vascular complications. Material and Methods: We conducted a prospective study enrolling 72 patients who consulted for HA injections to treat facial wrinkles. We used TL on one side of the face to obtain a vascular mapping of the face. The area undergoing testing was randomized for the TL technique. The primary study endpoint was sensitivity for identifying subcutaneous veins and the differences in complication rates between the side of the face where TL was used to guide the injection and the side of the face where no vascular exploration method was used. Results: TL sensitivity for locating the superficial temporal vein was 100%, 91% for the supratrochlear, supraorbital and infraorbital veins, and 95% for the dorsal nasal veins (p < 0.01). The complication rate was higher on the side of the face where no vascular exploration method was used (22.2% vs 2.7%; p = 0.010046). Conclusions: Our preliminary findings validate our hypothesis concerning the advantage of using TL to identify superficial veins before performing injections. This method is simple and affordable, and the learning curve is small. Level of Evidence IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266

The Outcomes Assessment of the Plasma Blade Technology in Upper Blepharoplasties: A Prospective Study on a Series of 25 Patients

Background: The Dermo Ablation Surgery (DAS) Medical® (Technolux, Italy) device is a plasma blade which induces a plasma voltaic arc causing a retraction in the epidermis and superficial dermis. Objective: The aim of our study is to prove the efficacy and safety of the DAS Medical® device in dermatochalasis size reduction. Methods: Our prospective study included 25 adult patients presenting with upper eyelid dermatochalasis undergoing a two-session treatment protocol with the DAS Medical® device (with a month treatment-free interval). The primary end point was the reduction in the size of the dermatochalasis. The secondary end points were patient satisfaction, and a blinded assessment of the outcomes was carried out by 15 plastic surgery specialists on post-procedural pictures. Results: The mean reduction in the size of the dermatochalasis was estimated at 2.47 mm on a 6-month follow-up (13.5 mm at T0 vs. 11.03 mm at 6 months, p = 0.0002) and 1.97 mm on a 12-month follow-up ((13.5 mm at T0 vs. 11.53 mm at 12 months, p = 0.0055). Eighty per cent of the patients and 78% of the assessing clinicians were globally satisfied with the results on a 12-month follow-up. The mean visual analogue pain score reported during the treatment was 4.5/10; MEOPA® was used in 23% of cases. No irreversible post-procedural sequelae (complications) were observed. Conclusion: Voltaic plasma arc treatment with DAS Medical® is an effective technique for non-invasive blepharoplasty on moderate dermatochalasis patients not suffering from palpebral lipoptosis and is very well tolerated. It can be usefully and successfully associated with surgery. Level of Evidence IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266

One-step facial feminization surgery: The importance of a custom-made preoperative planning and patient satisfaction assessment

Background: The availability of more accurate techniques used for transgender surgery has resulted in an increased number of patients requesting facial feminization surgery (FFS). The aim of this study was to present the FFS pre-operative planning of the authors’ male-to-female transsexual patients using photo-editing software, computer-aided design (CAD), modeling, and three-dimensional (3D) printing. Material and Methods: Twenty-five patients underwent FFS between November 2015 and May 2018. They were retrospectively included in this study, and their records were analyzed. Patients’ 3D facial models were printed and used for an accurate preoperative planning and shown to the patients. To assess patient satisfaction, the preoperative, six-month, and one-year postoperative scores obtained using Satisfaction With Life Scale (SWLS) and Subjective Happiness Scale (SHS) were compared. The scores following a normal distribution obtained for each patient were compared using a paired t-test. Results: The 3D model preparation mean time was 145±13.2 min. A total of 114 surgical procedures were carried out. The mean operative time was 420±23 min. Patients experienced no postoperative complication. All patients were very satisfied after surgery, with a significant difference between pre- and postoperative scores (p = 0.002; p = 0.03). Conclusion: With use of 3D modeling, surgeons are nearing a custom-made surgery era, especially required for complex procedures such as FFS. We suggest using 3D technology for a more accurate preoperative planning

Characterization of Contractile Forces Generated by Stretch Marks Fibroblasts: In Vitro Study

Abstract: Authors present a study about the contraction forces observed in striae distensae fibroblasts (SMF) in a collagen scaffold. Collagen lattices were used to study the mechanical behavior of SDF within the collagen matrix compared to the lattices produced using the healthy skin derived fibroblasts (NSF). A Forcebox device was used to measure the contractile forces. Striae Rubrae fibroblast’s contractile force was by 28% greater than that generated by the NSF and striae albae fibroblasts (P<0.05). Anomalies and especially differences in forces generated by SMF were observed through all our experiments. These findings complete and corroborate the results and information published in our previous studies. Level of Evidence V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266

Turbulence in circumstellar disks

We investigate the analogy between circumstellar disks and the Taylor-Couette flow. Using the Reynolds similarity principle, the analogy results in a number of parameter-free predictions about stability of the disks, and their turbulent transport properties, provided the disk structure is available. We discuss how the latter can be deduced from interferometric observations of circumstellar material. We use the resulting disk structure to compute the molecular transport coefficients, including the effect of ionization by the central object. The resulting control parameter indicates that the disk is well into the turbulent regime. The analogy is also used to compute the effective accretion rate, as a function of the disk characteristic parameters (orbiting velocity, temperature and density). These values are in very good agreement with experimental, parameter-free predictions derived from the analogy. The turbulent viscosity is also computed and found to correspond to an $\alpha$-parameter $2\times 10^{-4}<\alpha<2\times 10^{-2}$. Predictions regarding fluctuations are also checked: luminosity fluctuations in disks do obey the same universal distribution as energy fluctuations observed in a laboratory turbulent flow. Radial velocity dispersion in the outer part of the disk is predicted to be of the order of 0.1 km/s, in agreement with available observations. All these issues provide a proof of the turbulent character of the circumstellar disks, as well as a parameter-free theoretical estimate of effective accretion rates.Comment: Accepted for publication in Astronomy and Astrophysics, 13 page