Spin-Dynamics in Cold Gases of 87Rb and Atomic Hydrogen. The spins they are a-changin’

In this thesis the dynamics of cold gaseous atoms is studied. Two different atomic species and two different experimental techniques have been used. In the first part of the thesis experiments with Bose-Einstein condensates of Rb-87 are presented. In these experiments the methods of laser cooling and magnetic trapping of atoms were utilized. An atom chip was used as the experimental technique for implementation of magnetic trapping. The atom chip is a small integrated instrument allowing accurate and detailed manipulation of the atoms. The experiments with Rb-87 probed the behaviour of a falling beam of atoms outcoupled from the Bose-Einstein condensate by electromagnetic field induced spin flips. In the experiments a correspondence between the phases of the outcoupling radio frequency field and the falling beam of atoms was found. In the second part of the thesis experiments of spin dynamics in cold atomic hydrogen gas are discussed. The experiments with atomic hydrogen are conducted in a cryostat using a dilution refrigerator as the cooling method. These experiments concentrated on explaining and quantifying modulations in the electron spin resonance spectra of doubly polarized atomic hydrogen. The modifications to the previous experimental setup are described and the observation of electron spin waves is presented. The observed spin wave modes were caused by the identical spin rotation effect. These modes have a strong dependence on the spatial profile of the polarizing magnetic field. We also demonstrated confinement of these modes in regions of strong magnetic field and manipulated their spatial distribution by changing the position of the field maximum.

Tratamento a laser das malformações vasculares venosas

OBJETIVO: Avaliar se o tratamento das malformações vasculares venosas congênitas realizado com o emprego da tecnologia laser oferece clareamento ou desaparecimento das lesões com elevado grau de satisfação informado pelos pacientes e observado pelo médico. MÉTODOS: O estudo retrospectivo reuniu 26 pacientes, portadores de malformação vascular venosa, dos quais 73,07% eram do sexo feminino e que foram tratados com o aparelho PhotoDerm®. O tratamento das malformações vasculares necessitou uma média de 6,43 sessões, com intervalos de seis a oito semanas. Os pacientes incluídos neste estudo apresentavam pele tipo II (57,40%) e tipo III (42,30%), conforme classificação de Fitzpatric. A idade média variou de 14 a 61 anos, com média de 36,70 anos. Os dados foram obtidos através do preenchimento de protocolo informado pelo paciente. RESULTADOS: Foi informado elevado grau de satisfação (96,16%) e apenas um caso (3,84%) parcialmente satisfeito, considerando o clareamento ou desaparecimento das lesões. Houve desaparecimento das lesões avaliado pelo profissional médico em 80,76% dos casos e em 19,24% apenas clareamento. CONCLUSÃO: O tratamento das malformações vasculares venosas com o Photo-Derm® é seguro e eficiente tendo proporcionado elevado grau de satisfação dos pacientes assim como bons resultados em relação ao desaparecimento das lesões.

Effects of low intensity laser in in vitro bacterial culture and in vivo infected wounds

OBJECTIVE: to compare the effects of low intensity laser therapy on in vitro bacterial growth and in vivo in infected wounds, and to analyze the effectiveness of the AsGa Laser technology in in vivo wound infections. METHODS: in vitro: Staphylococcus aureus were incubated on blood agar plates, half of them being irradiated with 904 nm wavelength laser and dose of 3J/cm2 daily for seven days. In vivo: 32 male Wistar rats were divided into control group (uninfected) and Experimental Group (Infected). Half of the animals had their wounds irradiated. RESULTS: in vitro: there was no statistically significant variation between the experimental groups as for the source plates and the derived ones (p>0.05). In vivo: there was a significant increase in the deposition of type I and III collagen in the wounds of the infected and irradiated animals when assessed on the fourth day of the experiment (p=0.034). CONCLUSION: low-intensity Laser Therapy applied with a wavelength of 904nm and dose 3J/cm2 did not alter the in vitro growth of S. aureus in experimental groups; in vivo, however, it showed significant increase in the deposition of type I and III collagen in the wound of infected and irradiated animals on the fourth day of the experiment.

Effects of low-level laser therapy on wound healing

OBJECTIVE: To gather and clarify the actual effects of low-level laser therapy on wound healing and its most effective ways of application in human and veterinary medicine.METHODS: We searched original articles published in journals between the years 2000 and 2011, in Spanish, English, French and Portuguese languages, belonging to the following databases: Lilacs, Medline, PubMed and Bireme; Tey should contain the methodological description of the experimental design and parameters used.RESULTS: doses ranging from 3 to 6 J/cm2 appear to be more effective and doses 10 above J/cm2 are associated with deleterious effects. The wavelengths ranging from 632.8 to 1000 nm remain as those that provide more satisfactory results in the wound healing process.CONCLUSION: Low-level laser can be safely applied to accelerate the resolution of cutaneous wounds, although this fact is closely related to the election of parameters such as dose, time of exposure and wavelength.

Ablação dos vasos placentários com laser para tratamento da síndrome de transfusão feto-fetal grave: experiência de um centro universitário no Brasil

OBJETIVO: descrever os resultados do tratamento da síndrome de transfusão feto-fetal grave com a ablação vascular placentária a laser em um centro universitário do Brasil. MÉTODOS: estudo observacional retrospectivo que incluiu pacientes tratadas na Universidade Estadual de Campinas entre 2007 e 2009. A ablação vascular placentária foi realizada em casos de transfusão feto-fetal grave (estágios II, III e IV de Quintero) diagnosticados até a 26ª semana de gravidez. As principais variáveis avaliadas foram a idade gestacional no parto, a sobrevida (alta do berçário) de pelo menos um gêmeo e o comprometimento neurológico nos sobreviventes. Regressão logística foi utilizada para investigar a influência do comprimento do colo uterino, da idade gestacional e do estágio da doença (antes da cirurgia) sobre o parto/abortamento e o óbito fetal após a intervenção, sobre o parto pré-termo extremo e a sobrevida. RESULTADOS: em toda a amostra, pelo menos uma criança sobreviveu em 63,3% dos casos (19/30). Entre as gestantes que não tiveram parto/abortamento após à cirurgia, a sobrevida de pelo menos um gêmeo foi 82,6% (19/23). Nesse subgrupo (n=23), a idade gestacional média no parto foi 31,9 semanas e o comprometimento neurológico ocorreu em um neonato (1/31; 3,2%). O comprimento do colo uterino influenciou na ocorrência de parto/abortamento após a cirurgia (valor de p=0,008). Entre sete pacientes (7/30; 23,3%) que apresentaram essa complicação, cinco (5/7; 71,4%) tinham medidas do colo uterino menores do que 15 mm. Entre as 23 gestantes que não tiveram parto/abortamento após a cirurgia, os estágios mais avançados da doença (III e IV) aumentaram o risco de parto antes de 32 semanas (valor de p=0,025) e diminuíram a chance de sobrevida de ambas as crianças (valor de p=0,026). CONCLUSÕES: os resultados são semelhantes aos descritos na literatura. Na presente amostra, os principais fatores associados a piores resultados foram o colo uterino curto (menor do que 15 mm) e os estágios mais avançados da doença (III e IV) no momento em que o tratamento foi realizado.

Bartholin's gland cysts: management with carbon-dioxide laser vaporization

PURPOSE: To evaluate the effectiveness, recurrence rate, and complications of carbon-dioxide laser vaporization in the treatment of Bartholin's gland cysts. METHODS: A retrospective study including 127 patients with symptomatic Bartholin' gland cysts submitted to carbon-dioxide laser vaporization at our institution from January 2005 to June 2011. Patients with Bartholin's gland abscesses and those suspected of having neoplasia were excluded. All procedures were performed in an outpatient setting under local anaesthesia. Clinical records were reviewed for demographic characteristics, anatomic parameters, intraoperative and postoperative complications, and follow-up data. Data were stored and analyzed in Microsoft Excel® 2007 software. A descriptive statistical analysis was performed, and its results were expressed as frequency (percentage) or mean±standard deviation. Complication, recurrence, and cure rates were calculated. RESULTS: The mean age of the patients was 37.3±9.5 years-old (range from 18 to 61 years-old). Seventy percent (n=85) of them were multiparous. The most common symptom was pain and 47.2% (n=60) of patients had a history of previous medical and/or surgical treatment for Bartholin's gland abscesses. Mean cyst size was 2.7±0.9 cm. There were three (2.4%) cases of minor intraoperative bleeding. Overall, there were 17 (13.4%) recurrences within a mean of 14.6 months (range from 1 to 56 months): ten Bartholin's gland abscesses and seven recurrent cysts requiring reintervention. The cure rate after single laser treatment was 86.6%. Among the five patients with recurrent disease that had a second laser procedure, the cure rate was 100%. CONCLUSIONS: At this institution, carbon-dioxide laser vaporization seems to be a safe and effective procedure for the treatment of Bartholin's gland cysts.

The energy efficiency of chilled beam systems in an office building at different climates

Besides the sustaining of healthy and comfortable indoor climate, the air conditioning system should also achieve for energy efficiency. The target indoor climate can be ob-tained with different systems; this study focuses on comparing the energy efficiency of different air conditioning room unit systems in different climates. The calculations are made with dynamic energy simulation software IDA ICE by comparing the indoor cli-mate and energy consumption of an office building with different systems in different climates. The aim of the study is to compare the energy efficiency of chilled beam systems to other common systems: variable air volume, fan coil and radiant ceiling systems. Besides the annual energy consumption also the sustainability of target indoor climate is compared between the simulations. Another aim is to provide conclusions to be used in the product development of the chilled beam systems’ energy efficiency. The adaptable chilled beam system and the radiant ceiling system prove to be energy efficient independent of the climate. The challenge of reliable comparison is that other systems are not able to reach the target indoor climate as well as the others. The complex calculation environment of the simulation software, made assumptions and excluding of the financial aspects complicate comparing the big picture. The results show that the development of the chilled beam systems should concentrate on energy efficient night heating, flexible demand based ventilation and capacity control and possibilities on integrating the best practices with other systems. 

Laser-TIG hybrid welding process

Joining processes and techniques need to meet the trend of new applications and the development of new materials. The application in connection with thick and thin plates in industrial fields is wide and the joining technology is in very urgent need. The laser-TIG hybrid welding technology can play the respective advantages of both of them. One major advantage of the hybrid laser-TIG welding technology is its efficient use of laser energy. Additionally, it can develop into a high and new advanced welding technology and become a hot spot in both the application and research area. This thesis investigated laser –TIG hybrid welding with the aim of enlightening the reader on its advantages, disadvantages and future areas of improvement. The main objective is to investigate laser-TIG hybrid on the welding of various metals (steels, magnesium, aluminium etc.). In addition, it elaborates on various possible combinations on hybrid laser-TIG welding technology and their benefits. The possibility of using laser-TIG hybrid in welding of thick materials was investigated. The method applied in carrying out this research is by using literature review. The results showed that hybrid laser-TIG is applicable to almost all weldable metals. Also it proves to be effective in welding refractive metals. The possibility of welding with or without filler materials is of economic advantage especially in welding of materials with no filler material. Thick plate’s hybrid laser-TIG welding is showing great prospects although it normally finds its used in welding thin materials in the range of 0.4 to 0.8 mm. The findings show that laser-TIG hybrid welding can be a versatile welding process and therefore will be increasingly used industrially due to its numerous advantages and the development of new TIG arc that enhances its capabilities.

Capacity of an I-beam made of S960 QC based on Eurocode 3

The capacity of beams is a very important factor in the study of durability of structures and structural members. The capacity of a high-strength steel I-beam made of S960 QC was investigated in this study. The investigation included assessment of the service limits and ultimate limits of the steel beam. The thesis was done according to European standards for steel structures, Eurocode 3. An analytical method was used to determine the throat thickness, deformation, elastic and plastic moment capacities as well as the fatigue life of the beam. The results of the analytical method were compared with those obtained by Finite Element Analysis (FEA). Elastic moment capacity obtained by the analytical method was 172 kNm. FEA and the analytical method predicted the maximum lateral-torsional buckling (LTB) capacity in the range of 90-93 kNm and the probability of failure as a result of LTB is estimated to be 50%. The lateral buckling capacity meant that the I-beam can carry a safe load of 300 kN instead of the initial load of 600 kN. The beam is liable to fail shortly after exceeding the elastic moment capacity. Based on results in of the different approaches, it was noted that FEA predicted higher deformation values on the load-deformation curve than the analytical results. However, both FEA and the analytical methods predicted identical results for nominal stress range and moment capacities. Fatigue life was estimated to be in the range of 53000-64000 cycles for bending stress range using crack propagation equation and strength-life approach. As Eurocode 3 is limited to steel grades up to S690, results for S960 must be verified with experimental data and appropriate design rules.

On the numerical simulation of machining processes

Numerical simulation of machining processes can be traced back to the early seventies when finite element models for continuous chip formation were proposed. The advent of fast computers and development of new techniques to model large plastic deformations have favoured machining simulation. Relevant aspects of finite element simulation of machining processes are discussed in this paper, such as solution methods, material models, thermo-mechanical coupling, friction models, chip separation and breakage strategies and meshing/re-meshing strategies.

Application of cutting fluids in machining processes

In the last decade a lot has been discussed about the suitability of using cutting fluid in abundance to cool and lubricate machining processes. The use of cutting fluid generally causes economy of tools and it becomes easier to keep tight tolerances and to maintain workpiece surface properties without damages. In the other hand, it brings also some problems, like fluid residuals and human diseases. Because of them some alternatives has been sought to minimise or even avoid the use of cutting fluid in machining operations. Some of these alternatives are dry cutting and cutting with minimum quantity of fluid (MQF). The main goal of this work is to discuss these tendencies. Therefore, topics like kinds and methods of applications of modern cutting fluids and what are new in this area will unavoidably be considered. MQF and dry cutting techniques, their applications and where it is not possible to apply them will also be focused. To exemplify the topics, this work will describe some of the researches been developed in two important Brazilian Universities: State University of Campinas (UNICAMP) and Federal University of Uberlândia (UFU).

Chaos and Unpredictability in the Vibration of an Elasto-Plastic Beam

This contribution discusses the nonlinear dynamics of a pin-ended elasto-plastic beam with both kinematic and isotropic hardening. An iterative numerical procedure based on the operator split technique is developed in order to deal with the nonlinearities in the equations of motion. Free and forced responses for harmonic sinusoidal and square wave excitations are investigated. Numerical simulations present many interesting behaviors such as jump phenomena, sensitivity to initial conditions, chaos and transient chaos. These results indicate that there are practical problems in predicting the response of the beam even when periodic steady state response is expected.