## 4 How to Solve (at Least in Part) These Problems  
A lack of confidence in mathematical models has prompted attempts to assess and simplify the parameters governing heat fluxes between the neonate and the environment. In a thermally non-uniform environment (such as that encountered in a incubator) with radiant asymmetries, temperature gradients and turbulent air flow, the use of skin-temperature-controlled articulated thermal mannequins can bridge the gap between the simplification of scientific theory and the complexities of real nursing care.  
Surface temperatures are measured by sensors imbedded in the mannequin's solid copper structure. Using separate resistance wires, each segment is heated to a set-point temperature corresponding to that recorded in neonates.  
Mannequins have previously been used as replicas of term neonates [17; 21; 25]. Although these models give relevant information, the physical form is often over simplified (e.g., linked, smooth cylinders), the different body segments are not always thermally independent, and skin wetting is not simulated. Hence, this lack of similarity to a real neonate which can introduce errors into the calculation of heat transfers. To solve these problems, [PERSON] et al. designed an anthropomorphic, multisegment thermal mannequin representing a small-for-gestational age neonate (Figure 3) [18; 26]. Each body segment can act independently from the others, so as to simulate heterogeneity in skin temperatures and heat exchanges. The copper mannequin is painted with a thin layer of malt black paint, so that its surface emissivity is similar to that of human skin. Electrical wires placed inside each of the mannequin's members can be used to simulate the regional skin temperature heterogeneity (Figure 3b) recorded (using infrared thermography) for real neonates. In a study of a thermal mannequin simulating a neonate with very low birth weight, [PERSON] et al. [27] also included a sweating feature. Firstly, the mannequin's surface was covered with a black cotton stocking, in order to simulate water evaporation from the surface. Secondly, a pump system was used to supply water to each segment heated to a given set-point temperature by individual resistance wires. Hence, the level of skin wetting could be controlled as a function of the environmental conditions, in order to provide information on evaporative heat transfers for each body segment.  
Figure 3: (**a**) Anthropomorphic, multisegment thermal mannequins representing premature neonates with simulated birth weights of 900 g (left), 1500 g (right); (**b**) the mannequin’s regional skin temperatures (recorded using infrared thermography) simulate the heterogeneity observed in neonates nursed in closed incubators.  
Mannequins can be used to experimentally determine \(\overline{\mathrm{T}}_{\mathrm{r}}\) and several factors related to heat transfer coefficients with less uncertainty. For example, Figure 4 compares the (T\({}_{\mathrm{inc}}\)) calculated from a standard procedure (in which \(\overline{\mathrm{T}}_{\mathrm{r}}\) is assessed with a standard globe thermometer) with that obtained from experiments on the anthropomorphic, multisegment thermal mannequin [23]. The data showed that the standard procedure underestimated T\({}_{\mathrm{inc}}\), which increased the risk of body cooling. Differences ranging between 0.92 and 1.56 \({}^{\circ}\)C are clinically relevant if one considers that the range of T\({}_{\mathrm{inc}}\) for very premature neonates is narrow (perhaps even a single temperature point [28].