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1.
Hong Kong Med J ; 28(3): 204-214, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35697524

RESUMO

INTRODUCTION: Compared with young children who have acute lymphoblastic leukaemia (ALL), adolescents with ALL have unfavourable disease profiles and worse survival. However, limited data are available regarding the characteristics and outcomes of adolescents with ALL who underwent treatment in clinical trials. The aim of this study was to investigate the causes of treatment failure in adolescents with ALL. METHODS: We retrospectively analysed the outcomes of 711 children with ALL, aged 1-18 years, who were enrolled in five clinical trials of paediatric ALL treatment between 1993 and 2015. RESULTS: Among the 711 children with ALL, 530 were young children (1-9 years at diagnosis) and 181 were adolescents (including 136 younger adolescents [10-14 years] and 45 older adolescents [15-18 years]). Compared with young children who had ALL, adolescents with ALL were less likely to have favourable genetic features and more likely to demonstrate poor early response to treatment. The 10-year overall survival and event-free survival rates were significantly lower among adolescents than among young children (77.9% vs 87.6%, P=0.0003; 69.7% vs 76.5%, P=0.0117). There were no significant differences in the 10-year cumulative incidence of relapse, but the 10-year cumulative incidence of treatment-related death (TRD) was significantly greater among adolescents (7.2%) than among young children (2.3%; P=0.002). Multivariable analysis showed that both younger and older adolescents (vs young children) had worse survival and greater incidence of TRD. CONCLUSION: Adolescents with ALL had worse survival because they experienced a greater incidence of TRD. There is a need to investigate optimal treatment adjustments and novel targeted agents to achieve better survival rates (without excessive toxicity) among adolescents with ALL.


Assuntos
Recidiva Local de Neoplasia , Leucemia-Linfoma Linfoblástico de Células Precursoras , Adolescente , Protocolos de Quimioterapia Combinada Antineoplásica , Criança , Pré-Escolar , Intervalo Livre de Doença , Humanos , Incidência , Recidiva Local de Neoplasia/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Estudos Retrospectivos , Taxa de Sobrevida
2.
East Asian Arch Psychiatry ; 32(2): 34-38, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35732478

RESUMO

OBJECTIVES: To compare the incidence of upper respiratory tract infection (URTI) between inpatients at the Institute of Mental Health in Singapore and the general population over 8 years to determine the effectiveness of our infection control strategies. METHODS: Data for cases of influenza and URTI at our institute between January 2012 and December 2019 were collected. National data were derived from weekly infectious disease bulletins that report daily averages of people attending polyclinics/surgeries with influenza and URTI. Interrupted time series analyses were used to determine the impact of infection prevention and control strategies on incidence. RESULTS: Over the 8 years, there were 1607 cases of URTI involving 182 clusters, equal to 3.16 cases per 10 000 patient-bed-days. 965 (60%) cases and 95 (52%) clusters occurred in long-stay wards, whereas 642 (40%) cases and 87 (48%) clusters occurred in acute wards. The median cluster size was 12 in the long-stay wards and 7 in the acute wards (p < 0.0001). The spikes in cases in June and December may be attributed to the increased staff and visitor mobility during school vacations in June and December. Strategies implemented during the study period did not significantly reduce the incidence of URTI. Previous strategies implemented in 2005 to meet accreditation standards are more likely to be contributors. CONCLUSION: Infection control strategies of our institute appear to be effective, because the incidence of URTI was lower in our institute than in the community. The similar incidence of URTI in acute and long-stay wards indicates that service-user turnover is not a contributor. Rather, staff and visitors are more likely to be the vector. The larger clusters in long-stay wards indicates a greater risk of transmission in such settings. Increased activity in our institute during school vacations may be associated with an increase in cases in June and December. It is difficult to determine if strategies implemented during the study period successfully reduce the incidence of URTI.


Assuntos
Influenza Humana , Infecções Respiratórias , Humanos , Incidência , Infecções Respiratórias/epidemiologia , Infecções Respiratórias/prevenção & controle , Singapura/epidemiologia
4.
J Hosp Infect ; 116: 78-86, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34403765

RESUMO

AIM: To describe the nosocomial transmission of Air, multidrug-resistant, Acinetobacter baumannii, nosocomial, COVID-19 Acinetobacter baumannii (MRAB) in an open-cubicle neurology ward with low ceiling height, where MRAB isolates collected from air, commonly shared items, non-reachable high-level surfaces and patients were analysed epidemiologically and genetically by whole-genome sequencing. This is the first study to understand the genetic relatedness of air, environmental and clinical isolates of MRAB in the outbreak setting. FINDINGS: Of 11 highly care-dependent patients with 363 MRAB colonization days during COVID-19 pandemic, 10 (90.9%) and nine (81.8%) had cutaneous and gastrointestinal colonization, respectively. Of 160 environmental and air samples, 31 (19.4%) were MRAB-positive. The proportion of MRAB-contaminated commonly shared items was significantly lower in cohort than in non-cohort patient care (0/10, 0% vs 12/18, 66.7%; P<0.001). Air dispersal of MRAB was consistently detected during but not before diaper change in the cohort cubicle by 25-min air sampling (4/4,100% vs 0/4, 0%; P=0.029). The settle plate method revealed MRAB in two samples during diaper change. The proportion of MRAB-contaminated exhaust air grills was significantly higher when the cohort cubicle was occupied by six MRAB patients than when fewer than six patients were cared for in the cubicle (5/9, 55.6% vs 0/18, 0%; P=0.002). The proportion of MRAB-contaminated non-reachable high-level surfaces was also significantly higher when there were three or more MRAB patients in the cohort cubicle (8/31, 25.8% vs 0/24, 0%; P=0.016). Whole-genome sequencing revealed clonality of air, environment, and patients' isolates, suggestive of air dispersal of MRAB. CONCLUSIONS: Our findings support the view that patient cohorting in enclosed cubicles with partitions and a closed door is preferred if single rooms are not available.


Assuntos
Infecções por Acinetobacter , Acinetobacter baumannii , COVID-19 , Infecção Hospitalar , Infecções por Acinetobacter/tratamento farmacológico , Infecções por Acinetobacter/epidemiologia , Acinetobacter baumannii/genética , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Infecção Hospitalar/tratamento farmacológico , Infecção Hospitalar/epidemiologia , Farmacorresistência Bacteriana Múltipla , Humanos , Testes de Sensibilidade Microbiana , Pandemias , SARS-CoV-2
6.
BMC Pulm Med ; 20(1): 234, 2020 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-32867730

RESUMO

BACKGROUND: Cystic Fibrosis (CF) is a hereditary pulmonary and extra-pulmonary disease that occurs equally in men and women. However, a difference in morbidity and mortality rates between the sexes has been long documented. Similarly, a sex-disparity in disease severity has been reported in asthma as well. Studies done to date point to estrogen as a possible cause of this sex disparity in pulmonary outcomes in both conditions. CASE PRESENTATION: Here, we describe a case of a patient with CF and asthma/allergic bronchopulmonary aspergillosis (ABPA) undergoing sex reassignment therapy (male-to-female) and the negative impact it had on her lung function and frequency of pulmonary exacerbations in the context of increasing doses of exogenous estrogen. CONCLUSIONS: This case raises the possibility of a link between estrogen and worsening pulmonary outcomes and the need for further studies into transgender individuals with CF and/or asthma/ABPA as well as those undergoing high dose estrogen therapy for other indications.


Assuntos
Aspergilose Broncopulmonar Alérgica/complicações , Asma/complicações , Fibrose Cística/complicações , Estrogênios/efeitos adversos , Pulmão/fisiopatologia , Aspergilose Broncopulmonar Alérgica/fisiopatologia , Asma/fisiopatologia , Fibrose Cística/fisiopatologia , Estrogênios/administração & dosagem , Feminino , Humanos , Masculino , Testes de Função Respiratória , Cirurgia de Readequação Sexual , Pessoas Transgênero , Adulto Jovem
8.
Ann Chir Plast Esthet ; 63(2): 160-163, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29050858

RESUMO

Skin-sparing mastectomy and immediate implant-based breast reconstruction is technically a challenging procedures for women with large, ptotic breasts. This is usually performed using the Wise pattern incision resulting in an inverted T scar, which is associated with postoperative complications. The other challenge is obtaining adequate coverage of the prosthesis. We describe a technique that avoids the inverted T scar and provides a single horizontal scar with a double dermo-muscular layer coverage of the prosthesis.


Assuntos
Procedimentos Cirúrgicos Dermatológicos/métodos , Mastectomia/métodos , Tratamentos com Preservação do Órgão/métodos , Feminino , Humanos
9.
Trends Biotechnol ; 36(2): 216-227, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29132753

RESUMO

Although microalgae are a promising biobased feedstock, industrial scale production is still far off. To enhance the economic viability of large-scale microalgae processes, all biomass components need to be valorized, requiring a multi-product biorefinery. However, this concept is still too expensive. Typically, downstream processing of industrial biotechnological bulk products accounts for 20-40% of the total production costs, while for a microalgae multi-product biorefinery the costs are substantially higher (50-60%). These costs are high due to the lack of appropriate and mild technologies to access the different product fractions such as proteins, carbohydrates, and lipids. To reduce the costs, simplified processes need to be developed for the main unit operations including harvesting, cell disruption, extraction, and possibly fractionation.


Assuntos
Biotecnologia/economia , Filtração/métodos , Extração Líquido-Líquido/métodos , Microalgas/química , Proteínas de Algas/isolamento & purificação , Biocombustíveis/economia , Biomassa , Biotecnologia/métodos , Carboidratos/isolamento & purificação , Filtração/economia , Floculação , Humanos , Líquidos Iônicos/química , Lipídeos/isolamento & purificação , Extração Líquido-Líquido/economia , Microalgas/crescimento & desenvolvimento , Microalgas/isolamento & purificação , Micro-Ondas , Sonicação/economia , Sonicação/métodos
10.
Eur J Haematol ; 98(2): 160-168, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27706846

RESUMO

OBJECTIVES: The purpose of this study was to evaluate the predictive capacity of the European LeukemiaNet (ELN) classification of genetic risk in patients with acute myeloid leukaemia (AML) undergoing allogeneic stem cell transplantation (alloSCT). METHODS: We retrospectively analysed 274 patients transplanted at our centre between 2004 and 2014. RESULTS: The ELN grouping is comparable to the Southwest Oncology Group/Eastern Cooperative Oncology Group (SWOG/ECOG) stratification in predicting the outcome after alloSCT [overall P = 0.0064 for disease-free survival (DFS), overall P = 0.003 for relapse]. Patients with an intermediate-1 profile have a significantly elevated 5-yr relapse incidence as compared to favourable risk patients, that is 40% vs. 15%, [hazard ratio (HR) 2.58, P = 0.048]. An intermediate-1 risk profile is an independent predictor for relapse as determined by multivariate Cox regression analysis (HR 3.05, P = 0.023). In intermediate-1 patients, the presence of an FLT3 internal tandem duplication (FLT3-ITD) is associated with a significantly increased relapse incidence (P = 0.0323), and a lower DFS (P = 0.0465). FLT3-ITD is an independent predictor for overall survival, DFS and relapse incidence in the intermediate-1 subgroup. CONCLUSIONS: The ELN stratification of genetic risk predicts the outcome of patients with AML undergoing alloSCT. Patients with an intermediate-1 profile have a high risk for treatment failure due to relapse, which prompts the development of alternative treatment strategies.


Assuntos
Variação Genética , Leucemia Mieloide Aguda/diagnóstico , Leucemia Mieloide Aguda/genética , Adolescente , Adulto , Terapia Combinada , Feminino , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Humanos , Estimativa de Kaplan-Meier , Leucemia Mieloide Aguda/mortalidade , Leucemia Mieloide Aguda/terapia , Masculino , Pessoa de Meia-Idade , Prognóstico , Modelos de Riscos Proporcionais , Recidiva , Estudos Retrospectivos , Condicionamento Pré-Transplante , Transplante Homólogo , Falha de Tratamento , Resultado do Tratamento , Adulto Jovem
11.
J Biotechnol ; 225: 10-7, 2016 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-27002231

RESUMO

A mechanistic study was performed to evaluate the effect of salinity on cationic polymeric flocculants, that are used for the harvesting of microalgae. The polyacrylamide Synthofloc 5080H and the polysaccharide Chitosan were employed for the flocculation of Neochloris oleoabundans. In seawater conditions, a maximum biomass recovery of 66% was obtained with a dosage of 90mg/L Chitosan. This recovery was approximately 25% lower compared to Synthofloc 5080H reaching recoveries greater than 90% with dosages of 30mg/L. Although different recoveries were obtained with both flocculants, the polymers exhibit a similar apparent polymer length, as was evaluated from viscosity measurements. While both flocculants exhibit similar polymer lengths in increasing salinity, the zeta potential differs. This indicates that polymeric charge dominates flocculation. With increased salinity, the effectivity of cationic polymeric flocculants decreases due to a reduction in cationic charge. This mechanism was confirmed through a SEM analysis and additional experiments using flocculants with various charge densities.


Assuntos
Cátions/química , Clorófitas/fisiologia , Polímeros/química , Biomassa , Clorófitas/química , Clorófitas/metabolismo , Floculação , Microalgas/química , Microalgas/metabolismo , Microalgas/fisiologia , Salinidade
13.
Bioresour Technol ; 198: 797-802, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26454366

RESUMO

A mechanistic mathematical model was developed to predict the performance of cationic polymers for flocculating salt water cultivated microalgae. The model was validated on experiments carried out with Neochloris oleoabundans and three different commercial flocculants (Zetag 7557®, Synthofloc 5080H® and SNF H536®). For a wide range of biomass concentrations (0.49-1.37 g L(-1)) and flocculant dosages (0-150 mg L(-1)) the model simulations predicted well the optimal flocculant-to-biomass ratio between 43 and 109 mgflocculant/gbiomass. At optimum conditions biomass recoveries varied between 88% and 99%. The cost of the usage of commercial available flocculants is estimated to range between 0.15$/kgbiomass and 0.49$/kgbiomass.


Assuntos
Cátions/química , Clorófitas , Floculação , Microalgas , Polímeros/química , Biomassa , Clorófitas/química , Clorófitas/metabolismo , Microalgas/química , Microalgas/metabolismo
14.
Eur J Haematol ; 95(6): 498-506, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25598394

RESUMO

For patients with refractory acute myeloid leukemia (AML), allogeneic stem cell transplantation (alloSCT) represents the only curative approach. We here analyzed the long-term outcome of 131 consecutive patients with active AML, which was either primary refractory or unresponsive to salvage chemotherapy, transplanted at our center between 1997 and 2013. After a median follow-up of 48 months for the surviving patients, disease-free survival (DFS) at 5 yr post alloSCT was 26% (94% CI: 17-35). Relapses, most of which occurred within the first 2 yr from transplant, were the predominant cause of treatment failure affecting 48% (95%CI: 40-58) of patients, whereas non-relapse mortality was 26% (95%CI: 20-36) at 5 yr and thereafter. A marrow blast count ≥20% before alloSCT was an independent prognosticator associated with an inferior DFS (HR: 1.58, P = 0.027), whereas the development of chronic graft-versus-host disease (cGvHD) predicted an improved DFS (HR 0.21, P < 0.001) and a decreased relapse incidence (HR: 0.18, P = 0.026), respectively. These results indicate that alloSCT represents a curative treatment option in a substantial proportion of patients with refractory AML. A pretransplant blast count <20% before alloSCT and the development of cGvHD are the most important predictors of long-term disease control.


Assuntos
Transplante de Células-Tronco Hematopoéticas , Leucemia Mieloide Aguda/terapia , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Resistencia a Medicamentos Antineoplásicos , Feminino , Seguimentos , Doença Enxerto-Hospedeiro/etiologia , Doença Enxerto-Hospedeiro/prevenção & controle , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Humanos , Estimativa de Kaplan-Meier , Leucemia Mieloide Aguda/diagnóstico , Leucemia Mieloide Aguda/mortalidade , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Terapia de Salvação , Doadores de Tecidos , Condicionamento Pré-Transplante , Transplante Homólogo , Resultado do Tratamento , Adulto Jovem
15.
Eur J Haematol ; 94(5): 431-8, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25220715

RESUMO

For patients with acute myeloid leukemia (AML) early achievement of remission during induction treatment is an important predictor for long-term outcome irrespective of the type of consolidation therapy employed. Here, we retrospectively examined the prognostic impact of early remission (ER) vs. delayed remission (DR) in a cohort of 132 AML patients with an intermediate-risk karyotype undergoing allogeneic stem cell transplantation (alloSCT) in first complete remission (CR1). In contrast to patients showing DR, patients achieving ER had a significantly higher 3-yr overall survival (OS) and disease-free survival (DFS) of 76% vs. 54% (P = 0.03) and 76% vs. 53% (P = 0.03). Likewise, 3 yr after alloSCT the cumulative incidence of relapse (CI-R) was significantly lower in the ER subgroup as compared to patients achieving DR, that is, 10% vs. 35% (P = 0.004), whereas non-relapse mortality (NRM) did not differ significantly. Multivariate analysis identified DR as an independent prognosticator for an inferior DFS (HR 3.37, P = 0.002) and a higher CI-R (HR 3.55, P = 0.002). Taken together, these data may indicate that the rapid achievement of remission predicts a favorable outcome in patients with intermediate-risk AML undergoing alloSCT in CR1. In turn, the adverse effect of DR may not be fully overcome by alloSCT.


Assuntos
Transplante de Células-Tronco Hematopoéticas , Quimioterapia de Indução , Leucemia Mieloide Aguda/diagnóstico , Leucemia Mieloide Aguda/tratamento farmacológico , Adolescente , Adulto , Idoso , Antineoplásicos/uso terapêutico , Feminino , Humanos , Leucemia Mieloide Aguda/mortalidade , Leucemia Mieloide Aguda/patologia , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Recidiva , Indução de Remissão , Estudos Retrospectivos , Análise de Sobrevida , Fatores de Tempo , Transplante Homólogo , Resultado do Tratamento
17.
Bioresour Technol ; 169: 804-807, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25113884

RESUMO

Flocculation of microalgae is a promising technique to reduce the costs and energy required for harvesting microalgae. Harvesting marine microalgae requires suitable flocculants to induce the flocculation under marine conditions. This study demonstrates that cationic polymeric flocculants can be used to harvest marine microalgae. Different organic flocculants were tested to flocculate Phaeodactylum tricornutum and Neochloris oleoabundans grown under marine conditions. Addition of 10 ppm of the commercial available flocculants Zetag 7557 and Synthofloc 5080H to P. tricornutum showed a recovery of, respectively, 98% ± 2.0 and 94% ± 2.9 after flocculation followed by 2h sedimentation. Using the same flocculants and dosage for harvesting N. oleoabundans resulted in a recovery of 52% ± 1.5 and 36% ± 11.3. This study shows that cationic polymeric flocculants are a viable option to pre-concentrate marine cultivated microalgae via flocculation prior to further dewatering.


Assuntos
Organismos Aquáticos/metabolismo , Microalgas/metabolismo , Polímeros/farmacologia , Organismos Aquáticos/efeitos dos fármacos , Biomassa , Cátions , Floculação/efeitos dos fármacos , Microalgas/efeitos dos fármacos
18.
Eur J Haematol ; 92(2): 102-10, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24138573

RESUMO

We retrospectively analyzed the impact of cytogenetic abnormalities grouped according to the monosomal karyotype (MK) classification or the Southwest Oncology/Eastern Cooperative Oncology Group (SWOG/ECOG) definition in 263 patients with acute myeloid leukemia (AML) who underwent allogeneic stem cell transplantation (alloSCT) in complete remission (CR) at our center. Risk grouping using the MK criteria shows a highly significant difference in 5-yr overall survival (OS) ranging between 67%, for the most favorable, and 32%, for the poorest risk group (P = 0.001). Although similarly precise in predicting OS, the MK scheme better separates patients with respect to relapse incidence as compared to the SWOG/ECOG grouping (P = 0.0001 vs. P = 0.01). Notably, patients displaying non-MK abnormalities (MK-) had a 5-yr relapse incidence identical to those cytogenetically normal (CN), that is 24%. Multivariate analysis revealed that the MK classification is an independent prognosticator and superior in predicting OS (hazard ratios, HR 3.74, P = 0.01) and relapse incidence (HR 3.74, P = 0.005) as compared to the SWOG/ECOG criteria. Finally, subgroup analysis revealed that the prognostic capacity of the MK classification is highly significant in patients treated with standard myeloablative conditioning prior to alloSCT (P = 0.0011 for OS, P = 0.0007 for relapse). In contrast, the MK grouping failed to predict OS or relapse incidence in patients treated with reduced intensity conditioning. Taken together, these results indicate that the MK classification is superior in predicting the overall outcome of patients with AML undergoing alloSCT in CR. Furthermore, our data suggest that the genetic risk profile of MK- and CN patients is mostly overlapping in this setting.


Assuntos
Transplante de Células-Tronco Hematopoéticas , Cariótipo , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/terapia , Indução de Remissão , Adolescente , Adulto , Idoso , Feminino , Seguimentos , Doença Enxerto-Hospedeiro/etiologia , Doença Enxerto-Hospedeiro/prevenção & controle , Doença Enxerto-Hospedeiro/terapia , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Humanos , Leucemia Mieloide Aguda/mortalidade , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Prospectivos , Condicionamento Pré-Transplante , Transplante Homólogo , Resultado do Tratamento , Adulto Jovem
19.
Br J Radiol ; 86(1030): 20130253, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23966375

RESUMO

OBJECTIVE: To evaluate the feasibility of using three-dimensional (3D) ultrasound to assess the anatomy of the airway. METHODS: 11 young volunteers were recruited for 3D ultrasound and MRI of the airway. 3D ultrasound data were obtained from the level of the true vocal cords, cricoid cartilage and upper trachea. Multiplanar 3D ultrasound images were rendered and compared visually with corresponding MRI and cadaver anatomical sections. The anteroposterior (AP) and transverse diameter of the subglottic space and transverse diameter of the upper trachea were also measured in the 3D ultrasound and MR images and compared. RESULTS: The airway anatomy was clearly delineated in the multiplanar 3D ultrasound images. It was also possible to identify the cricothyroid junction, and a simple method to measure the AP diameter of the subglottic space using this landmark is described. We were also able to accurately measure the transverse diameter of the upper trachea, but the transverse diameter of the subglottic space was overestimated using ultrasound. There was a strong correlation for the AP diameter measurement (r=0.94, p<0.05) and moderate correlation for the transverse diameter measurement (r=0.82, p=0.002) of the subglottic space, and a strong correlation for the transverse diameter measurement (r=0.91, p<0.05) of the upper trachea, in the ultrasound and MR images. CONCLUSION: The anatomy of the adult airway can be assessed using 3D ultrasound. It can also be used to accurately measure the AP diameter of the subglottic space and the transverse diameter of the upper trachea. ADVANCES IN KNOWLEDGE: This is the first report to describe the use of 3D ultrasound to evaluate the anatomy of the upper airway and accurately measure the AP diameter of the subglottic space and the transverse diameter of the upper trachea.


Assuntos
Cartilagem Cricoide/anatomia & histologia , Cartilagem Cricoide/diagnóstico por imagem , Traqueia/anatomia & histologia , Traqueia/diagnóstico por imagem , Prega Vocal/anatomia & histologia , Prega Vocal/diagnóstico por imagem , Adulto , Estudos de Viabilidade , Feminino , Humanos , Imageamento Tridimensional , Imageamento por Ressonância Magnética , Masculino , Projetos Piloto , Ultrassonografia , Adulto Jovem
20.
J Acoust Soc Am ; 133(2): 697-708, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23363089

RESUMO

This paper reports a numerical study of the aeroacoustics of merging flow at T-junction. The primary focus is to elucidate the acoustic generation by the flow unsteadiness. The study is conducted by performing direct aeroacoustic simulation approach, which solves the unsteady compressible Navier-Stokes equations and the perfect gas equation of state simultaneously using the conservation element and solution element method. For practical flows, the Reynolds number based on duct width is usually quite high (>10(5)). In order to properly account for the effects of flow turbulence, a large eddy simulation methodology together with a wall modeling derived from the classical logarithm wall law is adopted. The numerical simulations are performed in two dimensions and the acoustic generation physics at different ratios of side-branch to main duct flow velocities VR (=0.5,0.67,1.0,2.0) are studied. Both the levels of unsteady interactions of merging flow structures and the efficiency of acoustic generation are observed to increase with VR. Based on Curle's analogy, the major acoustic source is found to be the fluctuating wall pressure induced by the flow unsteadiness occurred in the downstream branch. A scaling between the wall fluctuating force and the efficiency of the acoustic generation is also derived.


Assuntos
Acústica , Modelos Teóricos , Som , Acústica/instrumentação , Simulação por Computador , Desenho de Equipamento , Movimento (Física) , Ruído/prevenção & controle , Análise Numérica Assistida por Computador , Pressão , Reologia , Fatores de Tempo
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