Master of Science / Department of Mechanical and Nuclear Engineering / Steve Eckels / A new three dimensional transient human finger model was developed to predict the risk of frostbite in humans at different environmental conditions. The shape of the finger model was similar to that of a real human finger. Finite Element Techniques were used to build the finger model. Smith’s Model (1991) energy balance equations were used to calculate the temperatures in the current finger model. The current 3D finger model was validated against the experimental data of Wilson (1976) and Santee (1990). The model agreed well with the Wilson experiments and with the cold test in Santee experiments. The comparison indicates that the current finger model can be used to adequately predict the human finger responses in different environments. The current finger model was then tested in temperatures of 0, -10, -20, -25 and -30 oC and with different airspeeds 0, 3 and 6.8 m/s to assess the risk of frostbite in humans. Three resistances 0, 0.4 and 0.8 clo were used on the finger model to obtain responses in different environmental conditions. From the experimental results, an expression for safe glove resistance required to prevent frostbite in known temperatures was calculated. Also, the temperatures up to which a glove with known thermal resistance value can protect a human finger from frostbite was also computed.

Abstract Frostbite of the face and ears is a common problem in cold winters. Application of an emollient on the face is a traditional way to prevent frostbite in Finland. The preliminary results of an epidemiological study on frostbite in Finnish conscripts unexpectedly showed that the use of cold protecting emollients increased the risk of facial frostbite. This finding motivated studies on the effects and use of cold protecting emollients. 830 male Finnish conscripts answered a questionnaire concerning the use of cold protecting emollients, subjective experience of using them in cold and cumulative incidence of frostbite in the ears and face. Risk factors of frostbite were investigated in a prospective epidemiological study including 913 Finnish conscripts needing medical attention for frostbite of the ears or face and their 2478 matched, uninjured controls. Thermal properties of four different emollients were studied in vitro with a skin model and in vivo in experimental cold exposures of test persons. Test emollient was applied on one half of the face, as the other half acted as control. The skin temperatures of the face-halves were compared symmetrically by thermistors and infrared thermography. Subjective sensation of thermal half-difference was also registered. 21% of the conscripts had used emollients in the cold, a majority with an experience of protection. 47% of the conscripts had had frostbite in the head (42% in the ears and 23% on the face). There was a statistically significant correlation between the use of emollients and the incidence of facial frostbite in both epidemiological studies. Applying protective emollients formed an independent risk factor for frostbite of the cheeks, nose and ear lobes (odds ratios 3.3-5.6). The thermal insulation of test emollients on the skin model was minimal. On living skin, the applied half was somewhat cooler in a majority of comparisons. However, white petrolatum gave often a subjective perception of a warming effect. False sensation of safety may form the principal cause for the increased risk of frostbite associated with the use of emollients. When the warning symptoms of cold are weak, necessary protective measures are not carried out.

This thesis describes medical aspects of the expeditions of the Heroic Age of Antarctic exploration (1895-1922). It is divided into three sections. Section 1 describes the drugs and medical equipment taken to the Antarctic by these expeditions. There is an introductory discussion followed by papers on ophthalmic drugs, injections, inhalations and suppositories, oral drugs and topical preparations. Sledging medical cases are considered separately. Brandy was often used as a medicine and the medical uses of alcohol are described. Some expeditions took what were described as “medical comforts”. This term was sometimes used as a euphemism for alcoholic beverages but, in fact, encompassed a wide range of foods for invalids. Burroughs Wellcome and Co. supplied many of the expeditions with drugs and their medical chests. They used the expedition link in their advertising and the relationship between the expeditions and drug companies is described. Section 2 describes some of the medical problems encountered. The most serious problems were scurvy and a condition often called “polar anaemia”, which seems to be the same as a condition known at the time as “ship beriberi” and what is now described as “wet beriberi”. The controversy as to whether Captain Scott and his colleagues died of scurvy is also discussed. Other problems included frostbite and snow blindness. At least 11 general anaesthetics were given, including two for amputation of frostbitten toes. Psychological problems were common and there was some serious psychiatric illness including alcohol abuse. Section 3 describes the doctors and some of the research that they carried out. The most common research done by doctors was bacteriological. Most doctors collected biological data on the explorers including weights and haemoglobin measurements. This was largely for health monitoring but one doctor pursued physiological research. Three doctors and a medical student studied geology.

Background: (Papers I and II) The objectives were to first determine incidence and contributing factors to cold-related injuries in northern Sweden, both those that led to hospitalization and those that led to fatality.  (Papers III and IV) A further aim was to assess post-cooling hand-rewarming responses and effects of training in a cold environment, both on fingertip rewarming and on function of the autonomic nervous system, to evaluate if there was adaptation related to prolonged occupational cold exposure. Methods:  In a retrospective analysis, cases of accidental cold-related injury with hospital admission in northern Sweden during 2000-2007 were analyzed (Paper I).  Cases of fatal hypothermia in the same region during 1992-2008 were analyzed (Paper II).  A cohort of volunteers was studied before and after many months of occupational cold exposure. Subject hand rewarming response was measured after a cold hand immersion provocation and categorized as slow, moderate or normal in rewarming speed.  This cold provocation and rewarming assessment was performed before and after their winter training.  (Paper III).  Heart rate variability (HRV) was analyzed from the same cold provocation/recovery sequences (Paper IV). Results:  (Paper I) For the 379 cases of hospitalization for cold-related injury, annual incidences for hypothermia, frostbite, and drowning were 3.4/100,000, 1.5/100,000, and 1.0/100,000 inhabitants, respectively.  Male gender was more frequent for all categories.  Annual frequencies for hypothermia hospitalizations increased during the study period.  Hypothermia degree and distribution of cases were 20 % mild (between 32 and 35ºC), 40% moderate (31.9 to 28ºC), and 24% severe (< 28ºC), while 12% had temperatures over 35.0ºC.  (Paper II) The 207 cases of fatal hypothermia showed an annual incidence of 1.35 per 100,000 inhabitants, 72% in rural areas, 93% outdoors, 40% found within 100 meters of a building.  Paradoxical undressing was documented in 30%.  Ethanol was detected in femoral vein blood in 43%. Contributing co-morbidity was common including heart disease, previous stroke, dementia, psychiatric disease, alcoholism, and recent trauma.  (Paper III) Post-training, baseline fingertip temperatures and cold recovery variables in terms of final rewarming fingertip temperature and vasodilation time increased significantly in moderate and slow rewarmers.  Cold-related injury (frostbite) during winter training occured disproportionately more often in slow rewarmers (4 of the 5 injuries).  (Paper IV) At ‘pre- winter-training’, normal rewarmers had higher power for low frequency and high frequency heart rate variability.  After cold acclimatization (post-training), normal rewarmers showed lower resting power values for the low frequency and high frequency heart rate variability components.  Conclusions: Hypothermia and cold injury continues to cause injury and hospitalization in the northern region of Sweden.  Assessment and management is not standardized across hospitals.  With the identification of groups at high risk for fatal hypothermia, it should be possible to reduce the incidence, particularly for highest risk subjects; rural, living alone, alcohol-imbibing, and psychiatric diagnosis-carrying citizens.  Long-term cold-weather training may affect hand rewarming patters after a cold provocation, and a warmer baseline hand temperature with faster rewarming after a cold provocation may be associated with less general risk for frostbite.  Heart rate variability results support the conclusion that cold adaptation in the autonomic nervous system occurred in both groups, though the biological significance of this is not yet clear.

This report will deal with the process of creating an example based procedural distribution tool. This is accomplished within the Frostbite game engine editor, FrostEd. By using actual placements of objects in the editor as in-data, the tool provides the artist with an unmatched visual feel for calibrating its properties and settings. Note that this is a unique technique and was invented during the creation of this tool. The tool is based on a machine learning approach. It creates a feature vector from the example placements for each type of object. These vectors are then used to create statistical models which in turn are used to generate new object placements. The process of determining the position and rotation when generating an object is divided into two parts. A new concept called Feature Function (FF) is utilized to provide each element in the population with a probability to obtain a certain position and rotation.

We investigate the mesh colors method for per-face parameterization for texture-mapping of geometry, implemented in the game engine Frostbite 3, for the purpose of evaluating the method compared to traditional texture-mapping in a real-time application. Traditional UV-mapping often causes discontinuities which commonly results in visible seams in the end results. If any change is done to the vertex positions or the topology a remapping of the UV-map has to be done. Mesh colors aims to avoid these problems by skipping the transformation to 2D space as in UV-mapping, and associating color samples directly with the geometry of a mesh. The implementation was done in Frostbite 3 in C++ and HLSL shader code, and rendered with the DirectX graphics API. The results show that mesh colors is a viable alternative in a real-time renderer. Though not as fast as regular UV-mapped textures due to lack of hardware accelerated filtering operations, mesh colors is a realistic alternative for special cases where regular texture-mapping would be cumbersome to work with or produce sub-par results. Possible areas of future research are efficient data structures suitable to handle data insertion dynamically, compression of mesh colors data, and mesh colors in the context of mesh LOD generation.

No description available.

Just nu pågår stora anläggningsprojekt i Stockholm där Trafikverket försöker leda om trafiken från stadskärnan. Därför utfördes projektet Norra länken. Norra länkens tunnelkonstruktion är uppbyggd med ett inklädnadssystem och bergförstärkning som består av sprutbetong. I nuläget saknas information om vilka temperaturer som uppstår i en tunnelkonstruktion och på grund av detta appliceras Trafikverkets generella antagande vid dimensionering av vägtunnlar. Antagandet säger att tunnelkonstruktionens temperatur kommer att motsvara uteluftstemperaturen. Vilket innebär att sprutbetongen behöver vara frostbeständig och därmed appliceras XF4 eller XF2. För att förstå temperaturförhållandet i tunnelkonstruktioner bättre har Trafikverket utfört mätningar i Norra länken. Med ökad förståelse för temperaturförhållandena skulle det vara möjligt att korrigera det nuvarande kraven på exponeringsklasserna. Därmed var syftet med denna rapport att undersöka om mätningarna kunde hjälpa till att utforma ett underlag för framtida val av exponeringsklass i kommande tunnelprojekt med liknade inklädnadssystem. Metoden som användes för att kunna undersöka frågeställningarna var litteraturstudier, studiebesök och analys av mätningarna i Excel. Resultatet visade att bergförstärkningens temperatur aldrig hamnade under 0℃ under perioden som mätningarna erhölls medan inklädnadens temperatur understeg 0℃. Detta innebar att det inte fanns risk för frostskador i bergförstärkningen men att i inklädnaden fanns det risk för det. Däremot när analysen gjordes noterades att två av tre mätstationer blivit vattenskadade och orsakat mycket felaktig data och att all mätdata som erhölls var från milda vintrar. Vilket bidrar till att det finns en osäkerhet kring hur pålitliga mätvärdena var. Från analysen togs slutsatserna att det fanns för lite underlag för att kunna ta beslutet om att ändra val av exponeringsklass inför kommande tunnelprojekt och att Trafikverkets antagande inte stämde. Där av rekommenderas Trafikverket att fortsätta med mätningarna till planerat slutdatum 2025 och på så sätt erhålla tillräckligt med information för att i framtiden kunna utvärdera exponeringsklasserna på nytt. / Trafiverket strives to divert the traffic in Stockholm from the city center. In order to accomplish this, large construction projects are currently being planned and processed. One of them is a tunnel construction called Norra länken. The tunnel construction in Norra länken consists of a cladding system and rock reinforcement consisting of shotcrete. Currently there is not enough information on which temperatures that will occur in the tunnel construction and therefore Trafikverket’s general assumption is applied of when designing road tunnels. This means that the shotcrete needs to be frost resistant and that XF2 and XF4 is applied. In order to understand the temperature conditions in the tunnel construction Trafikverket decided to measure the temperatures in Norra länken. With an increased understanding of the temperature conditions it would be a possibility to alter the exposure classes that are currently applied. The purpose of this report is to investigate whether the resulting measurements could be used to design a basis for future selection of exposure class in coming road tunnel projects with similar cladding systems. For this report literature studies, field trips and analyzes of the measurements in Excel were used as a method to answer these research questions. The result showed that the temperature in the rock reinforcement never fell below 0℃ but that the cladding system did show temperatures below 0℃. Therefor it was only a risk for frostbite in the cladding system. However, when analyzing the data, it was noted that two out of three measuring stations were water damaged which caused a lot of incorrect data. The data was also only obtained from mild winters which makes it difficult to draw general conclusions from it. This contributed to uncertainties about how reliable the measured data was. From the analysis the conclusion was made that there was not enough information to support a decision that would alter the choice of exposure class in future tunnel projects. Thereby Trafikverket was recommended to continue with the measurements until the planed end date 2025 and by doing so they can obtain a sufficient amount of information to evaluate the exposure classes once again. / Temperaturmätning i inklädnadsystem och sprutbetong inom Norra Länken

Just nu pågår stora anläggningsprojekt i Stockholm där Trafikverket försöker leda om trafiken från stadskärnan. Därför utfördes projektet Norra länken. Norra länkens tunnelkonstruktion är uppbyggd med ett inklädnadssystem och bergförstärkning som består av sprutbetong. I nuläget saknas information om vilka temperaturer som uppstår i en tunnelkonstruktion och på grund av detta appliceras Trafikverkets generella antagande vid dimensionering av vägtunnlar. Antagandet säger att tunnelkonstruktionens temperatur kommer att motsvara uteluftstemperaturen. Vilket innebär att sprutbetongen behöver vara frostbeständig och därmed appliceras XF4 eller XF2. För att förstå temperaturförhållandet i tunnelkonstruktioner bättre har Trafikverket utfört mätningar i Norra länken. Med ökad förståelse för temperaturförhållandena skulle det vara möjligt att korrigera det nuvarande kraven på exponeringsklasserna. Därmed var syftet med denna rapport att undersöka om mätningarna kunde hjälpa till att utforma ett underlag för framtida val av exponeringsklass i kommande tunnelprojekt med liknade inklädnadssystem. Metoden som användes för att kunna undersöka frågeställningarna var litteraturstudier, studiebesök och analys av mätningarna i Excel. Resultatet visade att bergförstärkningens temperatur aldrig hamnade under 0℃ under perioden som mätningarna erhölls medan inklädnadens temperatur understeg 0℃. Detta innebar att det inte fanns risk för frostskador i bergförstärkningen men att i inklädnaden fanns det risk för det. Däremot när analysen gjordes noterades att två av tre mätstationer blivit vattenskadade och orsakat mycket felaktig data och att all mätdata som erhölls var från milda vintrar. Vilket bidrar till att det finns en osäkerhet kring hur pålitliga mätvärdena var. Från analysen togs slutsatserna att det fanns för lite underlag för att kunna ta beslutet om att ändra val av exponeringsklass inför kommande tunnelprojekt och att Trafikverkets antagande inte stämde. Där av rekommenderas Trafikverket att fortsätta med mätningarna till planerat slutdatum 2025 och på så sätt erhålla tillräckligt med information för att i framtiden kunna utvärdera exponeringsklasserna på nytt. / Trafiverket strives to divert the traffic in Stockholm from the city center. In order to accomplish this, large construction projects are currently being planned and processed. One of them is a tunnel construction called Norra länken. The tunnel construction in Norra länken consists of a cladding system and rock reinforcement consisting of shotcrete. Currently there is not enough information on which temperatures that will occur in the tunnel construction and therefore Trafikverket’s general assumption is applied of when designing road tunnels. This means that the shotcrete needs to be frost resistant and that XF2 and XF4 is applied. In order to understand the temperature conditions in the tunnel construction Trafikverket decided to measure the temperatures in Norra länken. With an increased understanding of the temperature conditions it would be a possibility to alter the exposure classes that are currently applied. The purpose of this report is to investigate whether the resulting measurements could be used to design a basis for future selection of exposure class in coming road tunnel projects with similar cladding systems. For this report literature studies, field trips and analyzes of the measurements in Excel were used as a method to answer these research questions. The result showed that the temperature in the rock reinforcement never fell below 0℃ but that the cladding system did show temperatures below 0℃. Therefor it was only a risk for frostbite in the cladding system. However, when analyzing the data, it was noted that two out of three measuring stations were water damaged which caused a lot of incorrect data. The data was also only obtained from mild winters which makes it difficult to draw general conclusions from it. This contributed to uncertainties about how reliable the measured data was. From the analysis the conclusion was made that there was not enough information to support a decision that would alter the choice of exposure class in future tunnel projects. Thereby Trafikverket was recommended to continue with the measurements until the planed end date 2025 and by doing so they can obtain a sufficient amount of information to evaluate the exposure classes once again.

A criocirurgia tem sido utilizada no tratamento de diferentes enfermidades de sistemas e órgãos, tanto na medicina humana quanto na medicina veterinária, sendo sua maior indicação o tratamento de dermatopatias. Contudo, efeitos adversos como a cicatrização lenta, cicatrizes extensas, disfunção estética e funcional, são relatados após a aplicação da substância criogênica. Ainda, existem as lesões que ocorrem naturalmente pela exposição ao frio extremo, afetando principalmente o nariz, dedos das mãos e pés ou orelhas. Na maioria das vezes resultam em gangrena e são bem comuns nos habitantes dos polos, turistas e praticantes de modalidades na neve. O presente trabalho tem como objetivo avaliar a influência das células-tronco mesenquimais de origem adiposa (ADSCs) na cicatrização de feridas cutâneas padronizadas e induzidas pelo nitrogênio líquido em ratos em duas fases da cicatrização cutânea: fase de proliferação e fase de remodelação. Utilizaram-se 83 ratos Wistar, machos, hígidos, com oito semanas de idade, sendo três animais usados como doadores de tecido adiposo para posterior obtenção das ADSCs e, 80 animais divididos aleatoriamente em oito grupos de tratamento (n=10). Através da aplicação do nitrogênio líquido pela técnica do spray aberto, realizou-se a indução de uma ferida, de aproximadamente 15 mm de diâmetro, na região dorsal de cada rato. A ferida recebeu o tratamento de acordo com o grupo ao qual pertencia: a) aplicação das ADSCs, por via subcutânea, no 15º dia (T1), no 30º dia (T2) ou nos dois tempos mencionados (T3) após a indução da lesão; b) aplicação da solução cloreto de sódio 0,9%, por via subcutânea, no 15º dia (S1), no 30º dia (S2) ou nesses dois tempos (S3) após a indução da lesão; c) nenhuma intervenção até o momento da eutanásia dos animais no 45º dia (C1) ou no 60º dia (C2). Macroscopicamente, a cada cinco dias, analisaram-se as medidas das lesões e calculou- se a área e a taxa de contração cicatricial das mesmas. No 45º ou no 60º dia pós- operatório, procedeu-se à coleta das biópsias para avaliação histopatológica e imuno- histoquímica. Com base nos resultados obtidos concluiu-se que: 1) o grupo T1 apresenta as maiores taxas de contração média das feridas no 20º e 25º dia; 2) o grupo T3 obteve a maior taxa de contração média das feridas no 30º dia pós-operatório; 3) o grupo T2 apresenta as maiores taxas de contração média das feridas no 55º e 60º dia; 4) o grupo T1 obteve diferença estatisticamente significativa em relação ao grupo sham (S3) quanto à neovascularização, avaliada pela técnica de imuno-histoquímica com o VEGF; 5) o grupo sham (S1) obteve diferença estatística significativa em relação aos grupos tratados com as ADSCs (T2 e T3) quanto à proliferação epitelial, avaliada pela técnica de imuno-histoquímica com o anticorpo Ki-67; 6) a terapia com as ADSCs proporciona uma relevante evolução clínica das feridas, podendo ser constatada ao final do período de avaliação por cicatrizes mais estreitas e compridas com as medidas da área final inferiores às cicatrizes dos grupos controle (C1 e C2) e sham (S1, S2 e S3). Propõem-se a necessidade de novos estudos com as ADSCs na cicatrização de lesões cutâneas provocadas pela criocirurgia ou por outra modalidade de congelamento, realizando biópsias com análises histopatológicas e imuno-histoquímicas em períodos de tempo menores e maiores aos realizados nesse estudo, a fim de detectar, respectivamente, diferenças no processo de cicatrização imediatamente após a aplicação das ADSCs e, também, acompanhar o remodelamento da cicatriz por um período mais longo. / Cryosurgery has been used to treat different diseases of systems and organs in both human and veterinary medicine. Although treatment of skin disorders is the leading indication, adverse effects such as delayed wound healing, large scars, esthetical deformation and functional impairment have been reported from administration of cryogenic substance. Beside that there are injuries caused naturally by the exposure to extreme cold weather conditions, which affect specially nose, fingers, toes and ears, mostly resulting in gangrene. These frostbites are very common in people who live in the Poles, tourists and snowboarders. This study aims to evaluate the influence of adipose-derived stem cells (ADSCs) on cutaneous wound healing that were standardized and induced by liquid nitrogen in rats according to two phases of cutaneous healing: proliferation phase and remodelling phase. For research purposes, 83 male, healthy and eight-weeks-old Wistar rats were required. Among 83 rats, three were used as adipose tissue donor for later ADSCs obtention and 80 Wistar rats were randomly divided in eight treatment groups (n=10). Through the application of liquid nitrogen by spraying technique, a 15 millimetres in diameter lesion was produced in the dorsal region of each rat. The wound received treatment according to the group it belonged: a) subcutaneously ADSCs application on the 15th day (T1), on the 30th day (T2) or in both periods mentioned (T3) after wound induction; b) subcutaneously application of 0.9% sodium chloride solution on the 15th day (S1), on the 30th day (S2) or in both periods mentioned (S3) after wound induction; c) no intervention until euthanasia on the 45th day (C1) or 60th day (C2) Macroscopically, every five days, the wounds were measured to calculate their area and healing rate. On the 45th and 60th postoperative day, biopsies were performed for histopathological and immunohistochemical evaluations. By the obtained results, the study concludes that:1) T1 group shows the highest wound average contraction rate on the 20th and 25th day; 2) T3 group presents the highest wound average contraction rate on the 30th postoperative day; 3) T2 group has the highest wound average contraction rate on the 55th and 60th day; 4) T1 group got a significant statistical difference in relation to sham group (S3) when it refers to neovascularization, which was evaluated by immunohistochemical technique with VEGF; 5) sham group (S1) obtained a significant statistical difference when compared to ADSCs groups (T2 and T3) with respect to epithelial proliferation, that was evaluated by immunohistochemical technique using antibody Ki-67; 6) the ADSCs therapy provides an important clinical evolution of wounds. This was verified at the end of evaluation period through narrower and longer scars with bottom end area measurements inferior to control group scars (C1 and C2) and sham group scars (S1, S2 and S3). Lastly, this paper proposes the necessity of new studies about the uses of ADSCs for cutaneous wound healing caused by cryosurgery or other sort of freeze. Furthermore it is opportune taking an action on studies that do biopsies with histopathological and immunohistochemical analyses using shorter and longer periods of time that those executed on this paper. Thus it will be possible to find out, respectively, differences on the healing process immediately after applying ADSCs and also follow up the scar remodelling for a longer period.