8 Conclusion and future work
We presented a novel approach for skinning virtual characters, which operates in real-time. Based on the embedding of the skin mesh into a deformable implicit volume, made of parts rigidly at- tached to each bone, it does not suffer from the loss of volume in- herent to standard geometric skinning methods. Choosing the way the implicit parts are combined enables us to tune transitions be- tween smooth and sharper skin shapes when a joint bends, to gen- erate contact surfaces between neighboring skin parts, and to drive organic bulging effects. As a result, our approach achieves visually plausible deformations of the different joints in a character’s body, even for extreme bending angles. Since no optimization or collision processing steps are required, our approach is robust and efficient. Lastly, computations being independent from one frame to the next, the method perfectly fits into standard animation pipelines. With our technique, the union operator is used to generate contacts between non-neighboring reconstructed skin parts, as done in the teaser image. In the future, we would like to investigate more ad- vanced field combination schemes to model a wider set of deforma- tions due to collisions between these non-neighboring parts. This may require extending the binary gradient-based composition oper- ators to n-ary compositions. The field values along contact surfaces could also be used, either to output contact forces to be applied to skeleton bones, or simply to detect that an angular limit is reached at the joint.
Fig. 5. Contact condition in the case of parametric surface
The most difficult in TCA is to solve a system of non-linear equations that traduce contact between the two surfaces. When the position of contact point(s) is (are) known, it’s easy to determinate the real gear ratio and transmission error, the contact paths on the gear tooth surfaces. Like the TCA for discrete shape, numerical methods are
These structures are revealed as whitish low capacitance pin-point spots due to the absence of contact between the probe and the epithelial lining of each empty infundibulum, or to the dry nature of a microcomedo. When inflammation is present, the papules appear as targetoid structures centered by a whitish comedo surrounded by a darker rim revealing a weakened skin barrier function and the presence of a discrete serosity exsudate (16).
Skin is subjected to many environmental threats, some of which altering the structure and function of the stratum corneum. Among them, surfactants are recognized factors that may influence irritant contact dermatitis. The present study was conducted to compare the variations in skin capacitance and corneosurfametry (CSM) reactivity before and after skin exposure to repeated subclinical injuries by 2 hand dishwashing liquids. A forearm immersion test was performed on 30 healthy volunteers. 2 daily soak sessions were performed for 5 days. At inclusion and the day following the last soak session, skin capacitance was measured and cyanoacrylate skin-surface strippings were harvested. The latter specimens were used for the ex vivo microwave CSM. Both types of assessments clearly differentiated the 2 hand dishwashing liquids. The forearm immersion test allowed the discriminant sensitivity of CSM to increase. Intact skin capacitance did not predict CSM data. By contrast, a significant correlation was found between the post-test conductance and the corresponding CSM data. In conclusion, a forearm immersion test under realistic conditions can discriminate the irritation potential between surfactant-based products by measuring skin conductance and performing CSM. In vivo skin preconditioning by surfactants increases CSM sensitivity to the same surfactants.
Evaluation of local expression and secretion of IL-12 after skin pIL-12 GET. The possibility to express ectopically a tumor antigen or a stimulatory protein of the immune system could help in the eradication of primary tumors and/or metastasis is of great interest. We decided to evaluate the efficiency of our newly devel- oped electrical parameters on the expression of a plasmid encoding the cytokine IL-12. IL-12 plays a central role on the activation of the immune system orienting the anti-tumor immune response toward a cytotoxic Th1-like immune response. In order to determine the efficiency of in vivo pIL-12 gene-electrotransfer (pIL-12 GET), 25 µg of pIL-12 or a same volume of PBS were intra-dermally injected in the left flank of C57Bl/6 mice. Rapidly within a few seconds, the skin was treated under HV-MV electrical parameters applied using contact electrodes (4 unipolar trains). The right side was not injected and not treated to be used as a control. Treated (left flank) and untreated (right flank of the same mice) skin biopsies of pIL-12-GET and PBS-GET treated mice were harvested between 1 and 14 days after treatment and incubated in complete medium for 24 h at 37 °C. IL-12 production was determined by ELISA in the skin cultured supernatant (Fig. 8 ). Small amount of IL-12 were detected in the supernatant of PBS treated skin (10 pg/ml/mg of protein). However, pIL-12 GET induces a significant increase in IL-12 secretion (173.7 ± 92.97 pg/mg of total proteins at day 1), reaching a peak at day 7 (670 ± 147.91 pg/mg of total proteins) which was maintained up to day 14 post-treatment. These results correlated with the expression of the tdTomato protein used to set up the GET electrical parameters. IL-12 production in the contralateral skin was significantly lower (70.0 ± 23.29 pg/ml at day 14) suggesting a local production of IL-12 at the treated site.
(a) created along a shearing plane (b) in the casting
Figure 1: Porosity lens defects
Semi-solid metal slurries are obtained by stirring the alloys during solidification in order to produce a “semi-solid” billet having a non-dendritic solid phase within a liquid metal matrix. During the preparation of this billet and subsequently during its transfer into the shot sleeve, the metal surfaces that are in contact with air as well as with the container walls form a “skin” around the semi-solid core. Moreover, when inserted horizontally into the shot sleeve, the contact between the bottom part of the billet and the shot sleeve wall is stronger because of gravity. As a result, the heat transfer is enhanced there and yields a partially solidified skin-layer. Most of the lubricant in the shot sleeve lies at its bottom and thus touches the external lower surface of the billet. When injected into the cavity, these contaminated surfaces may enter into the part, (figure 1a), and yield undesired defects like oxide film inclusions and lens shape porosities resulting from the decomposition of lubricant during the heat treatment, (see figure 1b).
the skin surface for a maximum of 5 s in order not to interfere with the water flux and content inside the stratum corneum. 30 The measurements were acquired in
real time and displayed on a computer screen where the capacitance values were transformed into a range of 256 grey levels to form a non-optical image. The great variety of skin surface patterns of hydration and topography can be viewed on these non-optical images. The darker pixels represent hydrated high capacitance spots. Clear pixels may represent dry spots of the skin or depressions and lines in the skin’s microrelief, impeding the contact between the probe and the stratum corneum. 20,21
Other elements of the skin microrelief (pores, wrinkles) are also imaged and can be manually quantified .
Surfactant-induced skin reaction
The dynamics of stratum corneum reactivity to surfactants is complex. Surfactants present in hygiene and skin care products are in part adsorbed at the skin surface , and they also permeate the SC where they interact with proteins and lipids. A number of physicochemical interactions exist between corneocytes and surfactants . One of the ear- liest events following surfactant-induced protein denatur- ation is perceived as corneocyte swelling . This condi- tion leads to a paradoxical and transient SC hydration following surfactant challenge in vivo . The structure and physical properties of the SC can be altered profoundly following prolonged contact with anionic surfactants [13, 15, 16]. As a consequence, minimal to severe irritation may
CSSS can be performed on any part of the body, with two main provisos. On the one hand, sampling from a hairy area is painful because of pulling out hairs, and the CSSS quality is inade- quate owing to the erratic contact with the SC. It is therefore advisable to shave these areas before any CSSS harvesting. On the other hand, the nat- ural intercorneocyte cohesion on the palms and soles is usually stronger than the cyanoacrylate bond, thus impairing the collection of a uniform sheet of corneocytes. However, a CSSS sampling on these sites is possible in certain physiopatho- logic conditions in which the SC texture is com- promised. Of note, oozing and eroded lesions cannot be assessed by CSSS.
3 Observations and analyses
The development of water vapour condensation on the ely- tra was observed from the time the water vapour flux was sent into the chamber. We chose an area of observation where the two surface geometries (valley and bump) could be focused at the same time (Fig. 5). Applying the flux of water vapour, we found that water always condensed firstly on the most depressed parts of the elytra (valleys). This can be due to two reasons: (i) a thermal effect, the valleys being slightly colder due to their close vicinity with the copper disk and exhibiting a lower thermal exchange with the surrounding atmosphere that is at higher tem- perature; (ii) a difference in nucleation barrier (e.g. due to a different wettability and/or different nucleation sites and roughness); nucleation in the valleys can thus be pro- moted greater than on the bumps. The shapes of water drops in the valleys appear more irregular than on the bumps, corresponding to a smaller contact angle and/or a larger contact angle hysteresis . Thermal and contact angle effects are investigated in the following experiments.
electrode design. For dermal GET, the field distribution must focus its high value only in the thin layer of the skin. This is obtained by non-invasive electrodes in contact with the skin as the stratum corneum is permeabilized within microseconds, and its contribution to the field distribution in the skin tissue becomes negligible 12 . Several electrode models have been described. The skin can be pinched between plated electrodes and the field is across the skin and the tissue underneath, where expression is detected 13 . An array of small rod-shaped electrodes (multi-electrode array (MEA)), in contact with the skin brought a pattern of localized expression. Transgene-expressing cells were observed exclusively in the epidermal layer of the skin due the very localized field distribution 14-16 . The surface intradermal EP (SEP) device where the electrodes are minimally invasive brings expression deeper in the skin 6 .
Deformations. We illustrate the use of our skinning technique with different composition operators, and on several models and poses (Figure 11). The union operator is used for the fingers joints in Figure 1(c) and the Dana model in Figure 10. It allows us to cor- rect the “elbow collapse” effects of the LBS as well as the smooth outgrowth produced by dual quaternions. It also nicely captures the aspect of a solid bone at joints with, inside the bent region, a con- tact between skin parts as illustrated in Figures 10. At bone joints, this makes our approach closer to real skin deformation than other real-time skinning techniques. The use of our new gradient-based blending operator, illustrated on Juna’s elbow and shoulder in Fig- ures 5(d), 12(b,c,d), and on the Armadillo’s knee in Figure 9(d), allows, in addition, the creation of a smooth skin deformation in- side the bend region for small rotation angles, before generating the contact for angles greater than π/2. This is especially useful where the generation of a hollow or a contact for small angles is unreal- istic. More subtle and also more realistic, for angles larger than π/2, the contact area is kept farther from the joint (Figure 12(b)). Finally, the bulge-in-contact operator can be used to mimic the tis- sues/fat bulging when fingers bend. This is illustrated in Figure 1(d) on phalanx deformations during the hand animation. In all these animations, smooth deformations and contact are adequately gen- erated while the mesh details are preserved, as illustrated on the Armadillo in Figure 11, its thigh and calf in Figure 9 and on Juna’s shoulder in Figure 12(d).
On holiday in southern Egypt, a 10-year-old girl received skin decoration on her right arm done with toothpicks drenched in henna dyes. As the picture faded with swimming and washing, the procedure was repeated three to four times. The exact recipe of the dye was unknown. Upon return home she developed an allergic contact dermatitis restricted to the site of the skin decoration (fig. 1). The girl had no previous history of contact dermatitis, but suffered from severe hay fever. Topical corticosteroids were applied and the lesions healed leaving marked hypopigmentation. Patch tests revealed a severe reaction to PPD (Table 1). Strong prick test reactions occurred for Herbacaea (mixtures 1, 2 and 3, Stallergenes, Waterloo, Belgium), weed mixtures (3, 5, 12 grasses, Stallergenes, Waterloo, Belgium) and 1% henna in water. No reaction to 1% indigo blue in water was observed. The final diagnosis was allergic contact dermatitis to PPD.
London Business School, CEPR, and ECGI.
What determines equilibrium securitization levels, and should they be regulated? To address these questions we develop a model where originators can exert unobservable e¤ort to increase asset quality, subsequently having private information regarding quality when selling ABS to rational investors. In equilibrium, all originators have low/zero retentions if they are …nancially constrained and/or prices are su¢ ciently informative. Asymmetric information lowers e¤ort in- centives in all equilibria. E¤ort is promoted by junior retentions, investor sophistication, and informative prices. Optimal regulation promotes e¤ort while accounting for investor-level ex- ternalities. It entails either a menu of junior retentions or a single junior retention with size decreasing in price informativeness. Mandated market opacity is only optimal amongst regula- tions failing to induce originator e¤ort.
Materials and methods
The study was approved by the ethics committee at our insti- tution, and was performed in accordance with the Declaration of Helsinki. Similar studies had not been performed before, so calculation of a minimum adequate size for groups of volun- teers was difficult. Eligible participants were enrolled when they attended for a routine checkup at the hospital. A total of 84 healthy Caucasian women from Western Europe without any past history or signs of skin disease were enrolled over a 5-year period. The only selection criterion was a body mass index (weight [kg]/height [m 2 ]) in the range of 19–23, ie,
Key words: environment, ethnicity, skin complexion, skin dryness, stratum corneum, xerosis
E thnicity plays an important role in the clinical pre- sentation of diverse skin disorders [1, 2]. In parti- cular, colour changes of lesional skin may be quite prominent in dark skin individuals. This may represent a psychologically distressing condition because of its persis- tent and visible nature. In particular, ashy hue may develop at the site of a variety of inflammatory skin disorders . Among them, ashy dermatitis which is synonymous with erythema dyschromicum persans is a distinctive melano- derma of unknown etiology combining macular erythema and presence of melanophages in the dermis [3, 4]. Ashi- ness is a lay term describing another condition characteri- zed by any xerotic process with loss of natural skin shine that prevails in individuals with dark skin complexion . Ashen and ashing skin are other terms used for a similar condition in reference to restricted body sites including the elbows and knees.
the most abundant. Collagens I and III represent close to 90 and 10 %, respectively, in the composition of dermal col- lagen fibrils, and collagen V is present as a minor fraction of about 2 %. Altogether, the fibrils with their associated proteins confer tensile strength to the skin and are pivotal for the general organization and stability of the dermal extracellular matrix among other functions [ 6 ]. The dermis can also be divided into two layers: the papillary dermis and the reticular dermis. The papillary dermis layer con- tains much thinner and less packed of collagen type III fibers, and it is more fibroblastic than the reticular dermis layer [ 7 ]. It is also shown that the papillary dermis contains much more components of glycosaminoglycans such as hyaluronic acid and dermatan sulfate [ 8 ]. In the dermis, collagen bundles form a three-dimensional mesh with other fibrillar proteins and interstitial cells, including a network of contractile fibroblasts. The structure is cemented by a hyaluronic acid and proteoglycan gel that allows for vis- cous flux and mediates interchange of water nutrients and metabolites between the blood, the lymph, the interstitial cell network and the epidermal layers [ 9 ]. The recent studies propose a refined skin-associated adipocytes as dermal adipose tissue, historically termed subcutaneous adipose, hypodermis and subcutis, which underlie the reticular dermis. The major hygroscopic agents, glycerol and hyaluronic acid play a key role in sky hydration and consequently prevent skin aging [ 10 ]. Furthermore, the cutaneous aging could be accelerated by the decrease of overall collagen types after menopause [ 11 ].
opening the way to occurrence of photoreactions. As a matter of fact, it is well known that TTET, both in small model systems (bases, nucleoside, and dinucleoside monophosphates) and DNA, leads to the formation of CPDs but not of 64PPs and Dewars. TT CPD is the major photoproduct, representing at least 90% of the lesions, much more than following UVB and UVC irradiation where its proportion among CPDs is approximately 50% (Fig. 4). Two main classes of molecules have been studied for their potency at mediating TTET. The first one are the aromatic ketones such as acetophenone or benzophenone 83 . This chemical structure is often
and transverse stress versus load in the skin are plotted. During the ﬁrst stage of the loading, using a ramp, the stress in the foam increases with the load. When the load is stabilized (constant level), the stress in the foam con- tinues to increase until it reaches the rupture point. If the value of the load of the level is greater than the static critical value, the transverse movement initiated by the buckling can only grow greater until the rupture occurs. Likewise, a double-ramp loading can be analyzed ( Fig. 15 ). The ﬁrst ramp is slow. It can cause a signiﬁ- cant transverse displacement in the foam, and thus a non zero stress state. By then applying a second, faster ramp, rupture is obtained faster than if only the latter ramp had been used to start with, because far less in- crease in stress is now needed to reach the rupture point. These calculations highlight the complexity of the problem. On the one hand, the load needed to cause rupture and the rupture moment greatly depend on the loading rate, but on the other hand, they depend more generally on the evolution of the load over time and also on the initial state of stresses in the foam, such as the one caused by a slow initial loading.