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This study assessed Cardiopulmonary Exercise Testing (CPET) in predicting oncological outcomes, post-operative recovery and complications in advanced ovarian cancer (AOC) cytoreductive surgery. We reviewed all patients who had CPET prior to AOC cytoreductive surgery with evidence of upper abdominal disease on preoperative imaging at the University Hospitals of Derby and Burton (UHDB) between August 2016 and July 2019. Patients were stratified by AT and maximum VO2 levels. 43 patients were identified. AT showed no relationship with major complications. 100% of patients in the AT ≥11 group received R0 (n = 21, 91.30%), or R1 (n = 2, 8.70%) cytoreduction, whereas in the AT <11 group, only 75.00% achieved and R0 or R1 resection (p = .02). Surgical complexity was higher in the AT ≥11 group (p = .001) and the VO2 ≥15 group (p = .0006). No other correlations were seen between AT or VO2 max and complications or readmissions. No difference in overall survival was seen if R0 resection was achieved.IMPACT STATEMENTWhat is already known on this subject? CPET testing allows pre-operative assessment of functional capacity to generate variables that can be used as a risk-stratification tool for major surgery. Whilst CPET testing has been shown to predict morbidity in non-gynaecological surgery, it remains unproven in cytoreductive surgery for ovarian cancer surgery despite being increasingly utilised.What do the results of study add? Our data suggest that CPET testing does not predict complication rates or survival in AOC. Patients with poor CPET performance are more likely to receive suboptimal cytoreductive outcomes from surgery.What are the implications of these findings for clinical practice and/or further research? CPET results should not be used to discount patients from cytoreductive surgery further research should address the interplay with nutrition, haematological markers, neoadjuvant chemotherapy and CPET performance.
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Procedimentos Cirúrgicos de Citorredução , Neoplasias Ovarianas , Limiar Anaeróbio , Toxinas Bacterianas , Teste de Esforço , Humanos , Neoplasias Ovarianas/cirurgiaRESUMO
The Middle to Later Stone Age transition is a critical period of human behavioral change that has been variously argued to pertain to the emergence of modern cognition, substantial population growth, and major dispersals of Homo sapiens within and beyond Africa. However, there is little consensus about when the transition occurred, the geographic patterning of its emergence, or even how it is manifested in the stone tool technology that is used to define it. Here, we examine a long sequence of lithic technological change at the cave site of Panga ya Saidi, Kenya, that spans the Middle and Later Stone Age and includes human occupations in each of the last five Marine Isotope Stages. In addition to the stone artifact technology, Panga ya Saidi preserves osseous and shell artifacts, enabling broader considerations of the covariation between different spheres of material culture. Several environmental proxies contextualize the artifactual record of human behavior at Panga ya Saidi. We compare technological change between the Middle and Later Stone Age with on-site paleoenvironmental manifestations of wider climatic fluctuations in the Late Pleistocene. The principal distinguishing feature of Middle from Later Stone Age technology at Panga ya Saidi is the preference for fine-grained stone, coupled with the creation of small flakes (miniaturization). Our review of the Middle to Later Stone Age transition elsewhere in eastern Africa and across the continent suggests that this broader distinction between the two periods is in fact widespread. We suggest that the Later Stone Age represents new short use-life and multicomponent ways of using stone tools, in which edge sharpness was prioritized over durability.
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Arqueologia , Florestas , Tecnologia/história , Clima Tropical , História Antiga , Humanos , QuêniaRESUMO
The literature examining the co-occurrence of gender dysphoria (GD) and autistic traits has so far been limited to a series of small case studies and two systematic studies, one looking at autistic traits in gender dysphoric children and the other set within the context of the extreme male brain hypothesis and looking at adults. The current study examined this co-occurrence of GD and autistic traits in an adult population, to see whether this heightened prevalence persisted from childhood as well as to provide further comparison of MtF versus FtM transsexuals and homosexual versus nonhomosexual individuals. Using the Autistic Spectrum Quotient (AQ), 91 GD adults (63 male-to-female [MtF] and 28 female-to-male [FtM]) undertaking treatment at a gender clinic completed the AQ. The prevalence of autistic traits consistent with a clinical diagnosis for an autism spectrum disorder (ASD) was 5.5 % (n = 3 MtF and n = 2 FtM) compared to reports of clinical diagnoses of 0.5-2.0 % in the general population. In contrast to the single previous report in adults, there was no significant difference between MtF and FtM on AQ scores; however, all of those who scored above the clinical cut-off were classified as nonhomosexual with respect to natal sex. Results were considered in the context of emerging theories for the observed co-occurrence of GD and autistic traits.
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Transtornos Globais do Desenvolvimento Infantil/epidemiologia , Transtornos Parafílicos/epidemiologia , Pessoas Transgênero/estatística & dados numéricos , Transexualidade/epidemiologia , Adolescente , Adulto , Encéfalo , Criança , Transtornos Globais do Desenvolvimento Infantil/diagnóstico , Transtornos Globais do Desenvolvimento Infantil/genética , Estudos de Coortes , Comorbidade , Feminino , Humanos , Entrevistas como Assunto , Londres/epidemiologia , Masculino , Pessoa de Meia-Idade , Transtornos Parafílicos/diagnóstico , Transtornos Parafílicos/genética , Fenótipo , Vigilância da População , Prevalência , Comportamento Sexual , Sexualidade , Inquéritos e Questionários , Adulto JovemRESUMO
The purpose of this study was to measure deformation of mandibular complete denture permanent bases after secondary curing. A cast of a flat mandibular edentulous ridge was duplicated ten times. A wax base was laid on the original cast, two wax sprues were attached and an overcast was made. The overcast was used to produce wax bases similar in outline and thickness on the duplicate casts. These were invested and following manufacturer's instructions ten similar acrylic resin bases were produced. The fitting surface of each denture base was scanned on a contacting scanner with an axis resolution of 1 microm and accurate to 25 microm. Denture teeth were waxed up on the base on the original master cast, an overcast was made to produce wax ups and tooth positions that were similar in outline and thickness to the original. These were processed, removed from the flasks and excess acrylic resin was removed. The denture bases were rescanned in an identical fashion to the first scanning procedure. Using commercially developed metrology software calibrated colour maps were generated for each denture base that illustrates measurements of differences between pairs of surfaces. Histograms showing distributions of distances between points were constructed. 50% of the points were separated by a mean 50 microm or less and that 90% of the points were separated by 160 microm or less. The maximum separation was of 380 microm. Complete denture permanent bases were not found to distort significantly as a result of being subjected to a second heat curing cycle as part of final processing of dentures.
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Resinas Acrílicas/química , Materiais Dentários/química , Bases de Dentadura , Prótese Total Inferior , Sulfato de Cálcio/química , Técnica de Fundição Odontológica , Materiais para Moldagem Odontológica/química , Técnica de Moldagem Odontológica , Planejamento de Dentadura , Humanos , Processamento de Imagem Assistida por Computador , Teste de Materiais , Polivinil/química , Siloxanas/química , Software , Propriedades de Superfície , Dente ArtificialRESUMO
OBJECTIVE: To compare the dichotomous results for 7 ulnar nerve clinical motor tests (Froment's sign, Wartenberg's sign, finger flexion sign, Jeanne's sign, crossed finger test, Egawa's sign, presence of clinical fasciculations) with motor nerve conduction velocity findings. DESIGN: A static group comparison design assessed for differences among dichotomous test outcomes with respect to motor nerve conduction velocity. SETTING: Five medical facilities throughout the United States provided data for this study. PARTICIPANTS: Records from participants (N=26) with diagnosed ulnar neuropathy at the elbow were included for data analysis. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Demographic data included age, sex, handedness, duration of symptoms, and the number of days between the clinical and electrodiagnostic exam. Other dependent variables included motor conduction velocity of the ulnar nerve, compound muscle action potential amplitude, and the dichotomous clinical motor test outcomes. RESULTS: Two motor signs, the presence of clinical fasciculations and a positive finger flexion sign, were identified more frequently (each present in 11 patients) than the other motor signs. An analysis of covariance revealed significant differences in motor nerve conduction velocity between positive and negative results for all the clinical motor tests except for the finger flexion sign. Significant chi-square analyses were found for the following comparisons: the presence of clinical fasciculations and Froment's sign, the finger flexion sign and the crossed finger test, Egawa's sign and Froment's sign, Warteberg's sign and Froment's sign, the crossed finger test and Froment's sign, and Egawa's sign and Wartenberg's sign. CONCLUSIONS: Some clinical motor tests are better than others at identifying early motor involvement, providing the rehabilitation professional some insight regarding the relative decrement of motor nerve conduction velocity when a selected test is positive.
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Eletrofisiologia/métodos , Síndromes de Compressão Nervosa/fisiopatologia , Nervo Ulnar/fisiopatologia , Adulto , Análise de Variância , Distribuição de Qui-Quadrado , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Condução Nervosa/fisiologia , Estados UnidosRESUMO
OBJECTIVES: The aim of this study was to determine constitution and physical properties of a prototype material based on Portland cement and assess biocompatibility compared with glass-ionomer cement by evaluating cell morphology. MATERIALS AND METHODS: Analysis of the material was performed using energy dispersive analysis (EDAX) and X-ray diffraction (XRD) analysis. Compressive strength and the effect of changing the mixing and curing conditions on the compressive strength of the materials were evaluated. Dimensional stability was evaluated by measuring water uptake of the materials. Biocompatibility was assessed at 1 and 28 days using a cell-culture technique and semi-quantitative cell morphological evaluation was performed by SEM. RESULTS: Analysis of the material showed that it was primarily composed of tricalcium silicate and dicalcium silicate. The compressive strength of the prototype cement and variants was comparable to Ketac Molar (47.98 N mm(-2) after 1 day, P>0.05). Vacuum mixing did not improve the compressive strength of the prototype cements at any age. Wet curing was detrimental to the neat cement at 1 day (35.98 N mm(-2), P=0.011) and 7 days (44.08 N mm(-2), P=0.025). The filler-replaced cement prototypes were more stable and less susceptible to changes in compressive strength by varying the curing method (P>0.05). The prototype material took up more water (0.9%) than glass-ionomer cement (1.7%) with P=0 after 1 day. Curing at 100% humidity resulted in a net loss of weight for all the materials tested. The test materials were less biocompatible than glass-ionomer cement at 1 day but their biocompatibility improved as the material aged. CONCLUSIONS: The constitution of the prototype material was broadly similar to that of mineral trioxide aggregate. The prototype cement could be a potential dental restorative material as its compressive strength compared well to an established restorative material. However, the material did not support cell growth, with biocompatibility being similar to that of glass-ionomer cement.
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Cimentos Dentários , Materiais Biocompatíveis/química , Materiais Biocompatíveis/toxicidade , Linhagem Celular Tumoral/efeitos dos fármacos , Força Compressiva , Cimentos Dentários/química , Cimentos Dentários/toxicidade , Análise do Estresse Dentário , Cimentos de Ionômeros de Vidro/química , Cimentos de Ionômeros de Vidro/toxicidade , Humanos , Concentração de Íons de Hidrogênio , Teste de Materiais , Espectroscopia de Perda de Energia de Elétrons , Molhabilidade , Difração de Raios XRESUMO
This study investigated the bond strength of heat-polymerized acrylic resin to titanium alloy using a proprietary bonding agent (GC Metalprimer II). Two surface treatments (sandblasted or roughened with a tungsten carbide bur) were compared for their effect on bond strength with or without thermal cycling. Eighty specimens of heat-polymerized acrylic resin bonded to titanium alloy (Ti-6Al-4V) were prepared: 20 specimens (control) and 60 used a bonding agent. Four-point bend testing was used to record the load at failure. A chemical bond between heat-polymerized resin and alloy was achieved using GC Metalprimer II with both surface treatments. Reduced failure loads were recorded after thermal cycling. The predominant mode of failure was cohesive. GC Metalprimer II was effective in achieving a chemical bond with either the sandblasted or roughened surfaces.
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Resinas Acrílicas/química , Ligas Dentárias/química , Metacrilatos/química , Autocura de Resinas Dentárias , Titânio/química , Ligas , Óxido de Alumínio/química , Corrosão Dentária/métodos , Temperatura Alta , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Maleabilidade , Polímeros/química , Estresse Mecânico , Propriedades de Superfície , Temperatura , Fatores de Tempo , Compostos de Tungstênio/química , Água/químicaRESUMO
The Middle to Later Stone Age transition in Africa has been debated as a significant shift in human technological, cultural, and cognitive evolution. However, the majority of research on this transition is currently focused on southern Africa due to a lack of long-term, stratified sites across much of the African continent. Here, we report a 78,000-year-long archeological record from Panga ya Saidi, a cave in the humid coastal forest of Kenya. Following a shift in toolkits ~67,000 years ago, novel symbolic and technological behaviors assemble in a non-unilinear manner. Against a backdrop of a persistent tropical forest-grassland ecotone, localized innovations better characterize the Late Pleistocene of this part of East Africa than alternative emphases on dramatic revolutions or migrations.
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The originally published version of this Article contained an error in Fig. 3, whereby an additional unrelated graph was overlaid on top of the magnetic susceptibility plot. Furthermore, the Article title contained an error in the capitalisation of 'Stone Age'. Both of these errors have now been corrected in both the PDF and HTML versions of the Article.
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"Social capital" has been critiqued as distracting attention from inequalities and policies that produce ill health. We support this critique insofar as social capital refers to the degree of trust and consensus in a locality, but find value in another dimension often included in the concept of social capital--social network ties and their associated communication patterns. We present a case study of Bushwick, a community of 100,000 people in Brooklyn NY, to suggest that the network aspect of "social capital" is useful to understand the active, on-the-ground processes by which residents of some neighborhoods beset by poverty, racial/ethnic subordination, and internal divisions (that themselves arise from inequalities and state policies) work out ways to defend their own and others' safety and health. We use a combination of population-representative survey data for young adults; sexual network survey data; and ethnography to show that Bushwick residents (including drug users and dealers) have used social network ties, communication, and normative pressures to reduce the extent to which they are put at risk by the drug trade and by drug-use-related HIV/AIDS in spite of conflicting interests, disparate values, and widespread distrust both of other community members and of dominant social institutions. This was done by "intravention" health communications, development of protective norms, informal negotiations, and other forms of adjustments within and among various groups--but it occurred in the absence of trust or consensus in this community. We conclude both (1) that social network interpretations of "social capital" might be better conceptualized in dialectic terms as collective action to survive in a harsh social order, and (2) that the social capital theory emphasis on trust and consensus as important causal factors for lowering drug-related risks at the community level may be a romanticized and erroneous perspective.
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Características de Residência , Apoio Social , Transtornos Relacionados ao Uso de Substâncias/epidemiologia , Adolescente , Adulto , Antropologia Cultural , Atitude , Crime , Feminino , Inquéritos Epidemiológicos , Humanos , Entrevistas como Assunto , Masculino , New York , Meio SocialRESUMO
OBJECTIVES: To determine deformation in phosphate-bonded investment (PBI) materials for "in-service conditions" and to investigate the influence of air bubble pores on deformation at 900 degrees C. METHODS: Surviving high and low strain-rate disc-rupture strength test samples were assessed for deformation. A dental centrifugal casting machine and a dental superplastic-forming machine were used to apply the loads. An indirect technique was used to measure the deformation of investment diaphragms with both a wide pore size distribution and with very low porosity for four investment materials. A total of 128 high strain-rate and 29 low strain-rate samples were investigated. A one-way analysis of variance was carried out. RESULTS: All but one of the high strain-rate test samples showed measurable deformation. All of the low strain-rate test samples containing pores showed measurable deformation. Six out of 14 samples, in which pores had been eliminated, showed no deformation. There was no statistically significant difference in deformation between samples with no pores and those with a large pore size distribution for either the high or low strain-rate tests (P>0.05). SIGNIFICANCE: PBI must survive all forming procedures without deformation if the resultant prosthesis is to fit. One hundred micrometres is generally recognized as the acceptable tolerance of fit for removable metal-based prostheses. The vast majority of deformations measured during this investigation were considerably greater than 100 microm.
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Revestimento para Fundição Odontológica/química , Acrilatos/química , Ar , Ligas , Ligas Dentárias/química , Técnica de Fundição Odontológica/instrumentação , Materiais Dentários/química , Elasticidade , Temperatura Alta , Humanos , Processamento de Imagem Assistida por Computador , Teste de Materiais , Microbolhas , Fosfatos/química , Porosidade , Estresse Mecânico , Propriedades de Superfície , Temperatura , Titânio/químicaRESUMO
BACKGROUND: Urine is a common biological sample to monitor recent drug exposure, and oral fluid is an alternative matrix of increasing interest in clinical and forensic toxicology. Limited data are available about oral fluid vs. urine drug disposition, especially for synthetic cannabinoids. OBJECTIVE: To compare urine and oral fluid as biological matrices to monitor recent drug exposure among HIV-infected homeless individuals. METHODS: Seventy matched urine and oral fluid samples were collected from 13 participants. Cannabis, amphetamines, benzodiazepines, cocaine and opiates were analyzed in urine by the enzyme-multipliedimmunoassay- technique and in oral fluid by liquid chromatography tandem mass spectrometry (LCMSMS). Eleven synthetic cannabinoids were analyzed in urine and in oral fluid by LC-MSMS. RESULTS: Five oral fluid samples were positive for AB-FUBINACA. In urine, 4 samples tested positive for synthetic cannabinoids PB-22, 5-Fluoro-PB-22, AB-FUBINACA, and metabolites UR-144 5-pentanoic acid and UR-144 4-hydroxypentyl. In only one case, oral fluid and urine results matched, both specimens being AB-FUBINACA positive. For cannabis, 40 samples tested positive in urine and 30 in oral fluid (85.7% match). For cocaine, 37 urine and 52 oral fluid samples were positive (75.7% match). Twenty-four urine samples were positive for opiates, and 25 in oral fluid (81.4% match). For benzodiazepines, 23 samples were positive in urine and 25 in oral fluid (85.7% match). CONCLUSION/DISCUSSION: These results offer new information about drugs disposition between urine and oral fluid. Oral fluid is a good alternative matrix to urine for monitoring cannabis, cocaine, opiates and benzodiazepines recent use; however, synthetic cannabinoids showed mixed results.
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Canabinoides/análise , Canabinoides/urina , Drogas Desenhadas/análise , Saliva/química , Detecção do Abuso de Substâncias/métodos , Adulto , Cromatografia Líquida , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Manejo de Espécimes , Espectrometria de Massas em Tandem , Distribuição TecidualRESUMO
OBJECTIVES: The aim of this study was to evaluate the suitability of fast-setting cement formulations based on Portland cement as dental core build-up materials using two different methods of testing compressive strength and evaluation of setting times. METHODS: Four fast-setting cements based on Portland cement and their four respective densified with small particle (DSP) mortars were tested for setting time, constitution of cement by EDAX, and compressive strength using International and British Standards. Ordinary Portland cement (OPC) was used as a control. RESULTS: All the fast-setting cements had a similar elemental composition to OPC and the setting times were less than 7 min. The compressive strength of OPC was different between the two methods (P<0.001). All the fast-setting cements tested showed no difference in compressive strength regardless of the method of testing at 1 and 7 days (P>0.05), but the cylinders showed a lower compressive strength at 28 days (P<0.05). The OPC DSP mortar showed poorer compressive strength than OPC (P<0.01) at all times for cube testing but not for cylinder testing, where no difference was observed. The fast-setting DSP mortars had a lower compressive strength at 1 day (P<0.005) with both methods. At later times, there was no difference between the cements and DSP mortars for the cubes. SIGNIFICANCE: The pure fast-setting cements set in <7 min and were not susceptible to changes in the compressive strength testing procedure at 1 and 7 days but at 28 days all the fast-setting cements had a significantly higher strength with the test using cubes (P<0.05). A reduction in strength was observed at 28 days in cylinder testing. Most of the cements tested did not show encouraging strengths, however, one of the prototype cements tested could be a prospective dental restorative material.
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Cimentos Dentários/química , Restauração Dentária Permanente , Óxido de Alumínio/química , Compostos de Cálcio/química , Força Compressiva , Microanálise por Sonda Eletrônica , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Silicatos/química , Propriedades de Superfície , Fatores de TempoRESUMO
OBJECTIVES: The aim of this study was to determine the constitution of a commercially available root-end filling material, mineral trioxide aggregate, (MTA) (ProRoot MTA, Tulsa Dental, Tulsa, OK, USA). The surface morphology of the material with various treatment conditions was also evaluated. METHODS: The constitution of two commercial versions of MTA was determined before and after mixing with water. The unset material was analysed using Energy Dispersive Analysis by X-ray (EDAX) in a scanning electron microscope (SEM) and X-ray diffraction (XRD). The first technique identified the constituent elements while XRD analysis identified the compounds or phases present. The set material was evaluated using EDAX. The surface morphology of the material stored under various conditions (100% humidity, immersion in water, or immersion in phosphate solution) was evaluated using SEM. RESULTS: The EDAX showed the white MTA to be composed primarily of calcium, silicon, bismuth and oxygen, with the gray MTA also having small peaks for iron and aluminum. The XRD analysis showed gray MTA to be composed primarily of tricalcium silicate and dicalcium silicate. The surface morphology of the materials differed under the various conditions, particularly following immersion in phosphate solution with crystal formation. SIGNIFICANCE: The commercial versions of MTA were shown to have broadly similar constitution to ordinary Portland cement except for the addition of bismuth compounds. The white MTA did not contain iron.
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Compostos de Alumínio/análise , Compostos de Cálcio/análise , Óxidos/análise , Materiais Restauradores do Canal Radicular/análise , Silicatos/análise , Alumínio/análise , Compostos de Alumínio/química , Bismuto/análise , Cálcio/análise , Compostos de Cálcio/química , Cristalografia , Combinação de Medicamentos , Microanálise por Sonda Eletrônica , Humanos , Umidade , Imersão , Ferro/análise , Microscopia Eletrônica de Varredura , Óxidos/química , Oxigênio/análise , Fosfatos/química , Materiais Restauradores do Canal Radicular/química , Silicatos/química , Silício/análise , Propriedades de Superfície , Água/química , Difração de Raios XRESUMO
AIMS: To determine relationships between drug use "hardness" (defined in increasing order of hardness as no drug use, marijuana use, non-injected heroin or cocaine use, crack smoking and injection drug use) and prevalences of several sexually transmissible infections among young adults in a high-risk neighbourhood. Drug users, particularly injection drug users and crack smokers, may be a core group for some sexually transmitted infections. DESIGN: Cross-sectional survey and assays of young adults from (a) a household probability sample and (b) a targeted sample of youth who have used injected drugs, crack, other cocaine or heroin. SETTING: Bushwick, an impoverished New York City minority neighbourhood with major drug markets. PARTICIPANTS: A total of 363 18-24-year-olds from a household probability sample; 165 Bushwick 18-24-year-olds who have used injected drugs, crack, other cocaine or heroin. MEASUREMENTS: Drug use by self-report; serum- and urine-based assays for HIV, hepatitis B and C, syphilis, gonorrhoea, chlamydia and herpes simplex (type 2). FINDINGS: Household-sample prevalences: HIV, hepatitis C and syphilis, 1%; gonorrhoea 3%; chlamydia 5%; past or present hepatitis B infection 8%; herpes simplex (type 2) 18%. In combined household and targeted samples, hepatitis C and HIV were concentrated among drug injectors. Herpes simplex (type 2), syphilis and hepatitis B increased among women with "hardest drug ever used". CONCLUSIONS: Using "harder" drugs is associated with some but not all of these infections. Prevention efforts should help youth avoid unsafe sex and higher-risk drugs.
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Infecções Sexualmente Transmissíveis/epidemiologia , Transtornos Relacionados ao Uso de Substâncias/epidemiologia , Adolescente , Adulto , Distribuição por Idade , Estudos Transversais , Feminino , Humanos , Masculino , Cidade de Nova Iorque/epidemiologia , Prevalência , Características de Residência , Fatores de Risco , Distribuição por Sexo , Infecções Sexualmente Transmissíveis/etiologia , Transtornos Relacionados ao Uso de Substâncias/complicaçõesRESUMO
OBJECTIVES: To investigate the sensitivity of a modified disc rupture test to variables affecting the strength of four phosphate-bonded investment materials under conditions closely resembling the in-service environment. This study examined the influence of air bubble pores on the strength of phosphate bonded investment materials at a temperature of 900 degrees C. METHODS: A modified disc rupture configuration was used to test a circular investment diaphragm with clamped edges, in tension, initiated by bending. A sequentially-varying molten metal mass was used to apply the load using an electronic centrifugal casting machine. The staircase method was used to determine the increase or decrease of the applied load with the standardized increment of load being no greater than 1 or 2g. The mean load applied to 30 samples defined the transition of survival to failure of the investment disc and was taken as a measurement of investment strength. Two material handling techniques, one giving virtually no pores and one showing a wide pore size distribution were used. RESULTS: The diaphragm clearly either failed or survived the test with the pattern of fracture indicating brittle failure. A statistically significant difference in strength (P<0.050) of diaphragms with and without air bubble pores was demonstrated for three materials. Fewer pores resulted in increased strength of those materials and produced a much reduced scatter of strength in the fourth. SIGNIFICANCE: The modified disc rupture test is sufficiently sensitive to identify variations in strength of phosphate bonded investment materials caused by differing pore size distributions.
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Revestimento para Fundição Odontológica/química , Fosfatos/química , Ar , Ligas/química , Análise de Variância , Técnica de Fundição Odontológica/instrumentação , Elasticidade , Eletrônica/instrumentação , Temperatura Alta , Humanos , Modelos Lineares , Teste de Materiais/métodos , Distribuição Normal , Maleabilidade , Porosidade , Pressão , Estresse Mecânico , Propriedades de Superfície , Resistência à Tração , Suporte de CargaRESUMO
OBJECTIVES: The phenomenon of superplasticity has made it possible to form complex shapes that require extremely high degrees of ductility in titanium alloy with minimal internal stresses. Combined with the use of an investment casting material as the die material, which makes possible the forming of re-entrant angles, it is possible to produce membranes for ridge augmentation. The aim is to characterise the metal alloy sheet and simulate the superplastic forming process in three dimensions to produce process parameters, namely gas pressure as a function of time, to accurately adapt the titanium sheet to the bone surface. METHOD: The surface of the die was digitised using a 3D laser scanning system (UBM-Keyence LC2450). Ti-6Al-4V sheet of 140 mm diameter was modelled using a grid of triangular membrane elements. This mesh was automatically refined during the simulations. Finite element simulation was carried out using the Superflag software program (University of Wales Swansea) Three different options for gas pressure control were adopted, namely, target flow stress, target strain rate and target energy dissipation. The pressure cycles produced from the simulation were used to form titanium alloy sheet at 900 degrees C using argon gas. The deformed regions of the formed sheet were then examined to determine the regions of contact with the die and to characterise surface damage. RESULTS: Comparison of the simulations with experiment showed that there was good agreement between simulated and experimental thickness distributions in most parts of the sheet that were examined. Interrupted tests showed that in the intermediate positions of the forming sheet the simulations were slightly ahead of the experiment. The target stress option was found to produce the best degree of adaptation and the sheet formed using this cycle showed good surface quality, whereas in highly deformed regions using the other target options, the sheet was found to have formed microcracks. The use of a solid lubricant on the surface of the forming sheet was not found to have a significant influence on the adaptation of the titanium alloy sheet except in areas of high deformation where the sheet perforated. SIGNIFICANCE: The finite element membrane formulation is well adapted to the superplastic forming of a ridge augmentation membrane prosthesis. The simulation accurately describes the evolution of the shape of the prosthesis and its thickness distribution with time, which allows the manufacturer to select an appropriate initial thickness of titanium alloy sheet prior to attempting to form the component. The investment dies are found to have sufficient strength to withstand the forming operation if a suitable orientation of the titanium sheet with respect to the die is adopted. A metal surface of good quality can be produced in the formed prosthesis using the appropriate gas control option.
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Aumento do Rebordo Alveolar/métodos , Ligas Dentárias , Análise do Estresse Dentário/métodos , Membranas Artificiais , Titânio , Ligas , Simulação por Computador , Revestimento para Fundição Odontológica , Técnica de Fundição Odontológica , Elasticidade , Análise de Elementos Finitos , Imageamento Tridimensional/instrumentação , Lasers , PressãoRESUMO
Recent interest by physicists in social networks and disease transmission factors has prompted debate over the topology of degree distributions in sexual networks. Social network researchers have been critical of "scale-free" Barabasi-Albert approaches, and largely rejected the preferential attachment, "rich-get-richer" assumptions that underlie that model. Instead, research on sexual networks has pointed to the importance of homophily and local sexual norms in dictating degree distributions, and thus disease transmission thresholds. Injecting Drug User (IDU) network topologies may differ from the emerging models of sexual networks, however. Degree distribution analysis of a Brooklyn, NY, IDU network indicates a different topology than the spanning tree configurations discussed for sexual networks, instead featuring comparatively short cycles and high concurrency. Our findings suggest that IDU networks do in some ways conform to a "scale-free" topology, and thus may represent "reservoirs" of potential infection despite seemingly low transmission thresholds.
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INTRODUCTION: Chest reconstruction in the female-to-male transgender individual is not a common procedure due to the low prevalence of intractable gender dysphoria. It means that few surgeons acquire sufficient expertise and many UK patients find themselves travelling abroad to centres such as Singapore, Amsterdam and the United States. PATIENTS AND METHODS: This study retrospectively evaluated 100 consecutive patients of a single surgeon over a 3-year period with prime outcome measures including surgical technique, complications, surgical revision and patient-reported satisfaction, using a simple, 1-5 linear analogue scoring system. RESULTS: The median age was 28 years with a median excision of 345 g per breast. Complications occurred in 11 patients, five of which required surgical haematoma evacuation. Chi(2) analysis failed to show a correlation between testosterone supplementation and haemorrhagic sequelae (p>0.1). To date, 16 patients have undergone supplementary surgery, predominantly axillary dog-ear revision. Overall patient-reported satisfaction was 4.25. CONCLUSIONS: Whilst only a part of the process in gender transitioning, chest reconstruction is important as it is frequently the initial surgical procedure and enables the large-breasted to live in their chosen role much more easily. Historically associated with high rates of both complication and revision surgery, this study demonstrates that both may be appreciably lower and associated with high levels of patient satisfaction so that there is a realistic, high-quality option for British patients who might otherwise feel the need to travel abroad for their surgery.