Determination of time-dependent skin temperature decrease rates in the case of abrupt changes of environmental temperature.

The present study deals with the development of a method for determining time-dependent temperature decrease rates and its application to postmortem surface cooling. The study concentrates on evaluating skin cooling behavior since data on skin cooling in the forensic literature are scarce. Furthermore, all heat transfer mechanisms strongly depend on the temperature gradient between body surface and environment. One of the main problems in modelling postmortem cooling processes is the dependence on the environmental temperature. All models for postmortem rectal cooling essentially presuppose a constant environmental temperature. In medico-legal practice, the temperature of the surrounding of a corpse mostly varies; therefore, an approach for extending the models to variable environmental temperatures is desirable. It consists in 'localizing' them to infinitesimal small intervals of time. An extended model differential equation is obtained and solved explicitly. The approach developed is applied to the single-exponential Newtonian model of surface cooling producing the following differential equation:T(S)'(t)=-lambda(t)(T(S)(t)-T(E)(t))(with T(S)(t) the surface/skin temperature, T(E)(t) the environmental temperature, lambda(t) the temperature decrease rate and T(S)'(t) the actual change of skin temperature or first-order derivative of T(S)). The differential equation directly provides an estimator:lambda(t)=-T(S)'(t)T(S)(t)-T(E)(t)for the time-dependent temperature decrease rate. The estimator is applied to two skin cooling experiments with different types of abrupt changes of environmental temperature, peak-like and step-like; the values of the time-dependent temperature decrease rate function were calculated. By reinserting them, the measured surface temperature curve could be accurately reconstructed, indicating that the extended model is well suited for describing surface cooling in the case of abrupt changes of environmental temperature.

Energy loss due to radiation in postmortem cooling. Part B: Energy balance with respect to radiation.

With the help of the law of Stefan and Boltzmann and a model for the cooling of exposed skin derived from the data of Lyle and Cleveland, the radiation energy loss ER can be calculated according to the following formula: [formula in text] where epsilon represents the emissivity of the skin (0.98), sigma the Stefan-Boltzmann constant, AR the radiating surface area, TS(0) the skin temperature at death, TE the environmental temperature and Z' = 0.1017 the gradient of the skin temperature curve. Additionally, an energy loss due to conduction and convection EC has to be taken into account. Comparing the energy losses due to radiation, conduction and convection with the decrease ET of the thermal energy in the body, calculated from mean heat capacity (3.45 kJ/(kg degrees K)), body mass and decrease of mean body temperature, there is a surplus of energy in the very early postmortem period, which can be explained only by an internal source of energy EI. Alltogether the following balance equation can be formulated: ET + EI = ER + EC Since the body temperature decreases in the early postmortem period, EI can be estimated by: EI(t) > or = max (ER(t) - ET(t), 0). The values obtained range up to 500 kJ for a medium sized (175 cm), medium weight (75 kg) body at an environmental temperature of 5 degrees C and are compatible with estimations of Lundquist for supravital energy production by breakdown of glycogen.

The significance of the anatomy of the skull base for mechanical modelling: a comparative study.

The present paper aims at analysing the significance of the anatomical structures of the human skull base for mechanical modelling. Three different Finite-Element (FE)-models of the human neurocranium were developed. The most complex model (1242 solid cuboid elements) contains holes and spaces functionally simulating the foramina and fissures and additional element layers for the inner relief of the skull base (petrous temporal and sella). Of the less complex models, one (1256 solid cuboid elements) includes only the 3 cranial fossae, while the other (400 solid cuboid elements) represents a rotationally symmetrical ellipsoid with a hole for the foramen magnum. Two linear static loadcases, one with a transverse loading direction (pressure of 250 kg on the left temporal surface, bearing on the right temporal surface) and the other with a sagittal loading direction (pressure of 250 kg on the frontal surface, bearing on the occipital surface) were computed. The loadcase analyses show, qualitatively and quantitatively, similar equivalent von Mises stress values and distributions in the two more complex models while the elementary geometric model leads to significantly different absolute stress values and distributions. The results of the most complex model are highly compatible with experimental observations on transverse and sagittal fractures of the skull base.

Energy loss due to radiation in postmortem cooling. Part A: quantitative estimation of radiation using the Stefan-Boltzmann law.

Conduction and convection are assumed to account for most of the energy loss from the dead body to the (cooler) environment. There are no quantitative estimations in the literature for the contribution of radiation to heat loss. The aim of the present paper was to estimate the radiation energy loss in postmortem cooling. The Stefan-Boltzmann law is used and combined with a single-exponential model for the cooling process of the skin derived from experimental data of Lyle and Cleveland (1956). The influence of various factors (e.g. skin temperature, environmental temperature, body mass and body height) on the amount of radiation emitted was investigated. The radiation energy is quantitatively described as a function of time. The radiation energy loss ranged from approximately 200 kJ in small (165 cm) and lean (50 kg) bodies at room temperature (20 degrees C) to approximately 600 kJ in tall (185 cm) and over-weight (100 kg) bodies at outdoor temperature (5 degrees C) in the first hour postmortem.

Suppression of vagus-mediated pancreatic polypeptide release by the mu-opiate receptor agonist loperamide in man.

1. Morphine suppresses the release of pancreatic polypeptide, a hormone under vagal cholinergic control. The intention of the study was to detect whether the mu-opiate receptor agonist loperamide is also able to inhibit pancreatic polypeptide release, and to define its site of action. 2. In groups of healthy subjects (n = 6 each) stimulation of pancreatic polypeptide was assessed in five different tests: (i) insulin-hypoglycaemia; (ii) modified sham feeding; (iii) intravenous infusion of the cholecystokinin analogue ceruletide; (iv) injection of corticotropin releasing hormone; (v) infusion of the muscarinic acetylcholine agonist bethanechol. All tests were performed after oral application of either a placebo or loperamide (16 mg), tests (ii) and (iii) were repeated with loperamide in smaller doses (2 and 6 mg), with loperamide plus naloxone, with naloxone alone, and with infusion of atropine. Plasma concentrations of pancreatic polypeptide were measured radioimmunologically. 3. Release of pancreatic polypeptide in test (i) to (iv) was completely blocked by 16 mg loperamide, whereas bethanechol-stimulated release (test 5) was not influenced. Tests (ii) and (iii) showed that the inhibition was dose-dependent and could be attenuated by naloxone. The inhibitory effect of loperamide was comparable with that of atropine. 4. We conclude that loperamide causes a dose-dependent inhibition of pancreatic polypeptide release mediated by vagal-cholinergic pathways, but does not have an atropine-like peripheral action.

Pulmonary giant cells and traumatic asphyxia.

A morphometrical analysis was performed to elucidate the significance of pulmonary polynuclear giant cells as a histological sign of asphyxiation. A total of 13 cases of homicidal strangulation of throttling, 8 cases of traumatic asphyxia due to chest compression and 10 control cases (cause of death: severe head injury, no signs of aspiration or other relevant pulmonary alterations, smokers and non-smokers) were investigated. The number of alveolar macrophages containing 1 or 2 nuclei and of polynuclear giant cells per microscopic field (0.000025 cm2) was estimated and a statistical evaluation was carried out. A considerable individual variation was observed in all groups with a tendency to higher numbers of cells in cases of smokers or advanced individual age. However, no significant differences were detectable in the content of alveolar macrophages and in particular of polynuclear giant cells between the asphyxiated individuals and the controls. Since polynuclear giant cells occurred in similar amounts in healthy, functionally normal lungs of non-asphyxiated individuals, the detection of such cells cannot be regarded as a reliable indicator for asphyxiation.

[Biomechanical and morphologic reconstruction of a questionable case of child abuse]. / Biomechanische und morphologische Rekonstruktion einer fraglichen Kindesmisshandlung.

A 3-month-old baby died 8 days after admission to the hospital as a result of injuries received under unknown circumstances. The forensic autopsy revealed a fracture of the scull and a severe blunt injury to the head and brain. Histological investigation of the reactive changes at and around the edges of the fracture showed that the trauma could not possibly have been congenital. According to the defendant, the baby boy had been lying on the table used for changing his nappy and almost fell off it. The defendant moved "instinctively" to catch him, and this "reflex movement" caused the injuries observed. The event was then reconstructed by the criminal investigators and this reconstruction, coupled with the authors' biomechanical experiments using stroboscopic recording, revealed that the defendant's statement could not be true, as the force necessary to inflict the injuries was much greater than could be explained by an attempt to catch the baby.

[Biomechanical analysis of movement using stroboscopy]. / Biomechanische Bewegungsanalysen mittels Stroboskopie.

In cases when violence has occurred in some form and its associated forces are subject to expert evaluation. For a mathematical assessment of the intensity of the acting forces there is often a lack of confident basis data, which is why an experimental study is necessary. A simple testing arrangement with a photocamera and flashlight in stroboscopic mode provides a convincing pictorial representation of movement and velocity. The method is described with some examples of applications by experts.

On the estimation of lay-time by measurements of rigor mortis.

Measurements of the torgue to overcome rigor mortis on the legs of 101 male human cadavers at 5 degrees C are reported. There seems to exist an upper limit, which is dependent on the lay-time, above which no value occurs, but below which every value may be found. By calculating the 90% tolerance limits for lay-times grouped at 12-hourly intervals, this upper limit was found to decrease exponentially with lay-time. This may be used for the estimation of maximum lay-times from rigor mortis measurements.

[Pacemaker and seat belt (author's transl)]. / Herzschrittmacher und Sicherheitsgurt.

Although seat-belt-induced traffic accident injuries to wearers of pacemakers are rare, about 50,000 pacemaker patients have to "buckle up." A study of 450 pacemaker patients indicated that, as in the general population about 50% use their seat belts. Fifty percent of the patients felt uncomfortable or showed local damage of the area overlying the pacemaker. Studies with dummies revealed a 7-cm upward dislocation of the pacemaker caused by the negative acceleration and by the seat belt itself during the crash. This could be prevented by an external cap protecting the pacemaker.

[Measurements of rigor mortis on human skeletal muscles in situ (author's transl)]. / Totenstarremessungen an menschlichen Skelettmuskeln in situ.

The torque, necessary to break the rigor mortis of arms and legs at 17 female and 35 male cadavers stored at a temperature of 4 degrees C was determined. The values show differences between male and female cadavers to an extent, that both groups have to be treated separately. Relating the torque to the diameter or the cross section of the limb does not eliminate the differences: Frequently considerable differences between left and right limbs were obtained, however, without preference of one side over the other. There is no direct functional relationship between post mortem time and the intensity of r.m., but the values occasionally allow estimates on the maximum time post mortem.