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Ju Hyeon Kim,Domenic J. Previte,Kyung Jae Yoon,Kyung Mun Kim,Edwin Murenzi,Kyong Sup Yoon,J. Marshall Clark,Si Hyeock Lee 한국응용곤충학회 2016 한국응용곤충학회 학술대회논문집 Vol.2016 No.04
Human body and head lice are obligatory human ectoparasites. Although both body and head lice belong to a single species, Pediculus humanus, only body lice are known to be a vector of several bacterial diseases. The higher vector competence of body lice is assumed to be due to their weaker immune response than that of head lice. To test this hypothesis, immune reactions were compared between body and head lice following infections by two model bacteria, Staphylococcus aureus and Escherichia coli, and a human pathogen, Bartonella quintana. Following dermal or oral challenge, the number of these bacteria increased both in hemocoel and alimentary tract of body lice but not in head lice and the viability of the B. quintana was significantly higher in body louse feces, the major route of infection to human. In addition, body lice showed the lower basal/induced transcription level of major immune genes, cytotoxic reactive oxygen species and phagocytosis activity compared with head lice. These findings suggest that a reduced immune response may be responsible, in part, for the increased proliferation and excretion of viable bacteria which are associated with the high level of human infectivity seen in body versus head lice.
Proliferation and Excretion of Bartonella quintana in Body and Head Lice Following Oral Challenge
Ju Hyeon Kim,Domenic J. Previte,Kyong Sup Yoon,John M. Clark,Si Hyeock Lee 한국응용곤충학회 2013 한국응용곤충학회 학술대회논문집 Vol.2013 No.04
The body and head lice (Pediculus humanus humanus and Pediculus humanus capitis, respectively) are hematophagous ectoparasites of humans and only the body louse between two is known to transmit three bacterial diseases through its feces. The proliferation profiles of Bartonella quintana, the causative agent of trench fever, inside the louse body and its excretion patterns were investigated in the two louse subspecies following oral challenge with B. quintana-infected blood meal. The initial density of B. quintana was sustained inside head lice without any noticeable proliferation for the entire period after infection. In contrast, B. quintana proliferated rapidly inside body lice and the maximum density reached at 10 days post-infection. The numbers of bacteria detected in feces from infected lice were almost the same and steadily decreased over time in both body and head lice. Nevertheless, the viability of the bacteria, as determined by fluorescence, was significantly higher in body louse feces, especially at 1 day post-infection and this tendency lasted for 11 days. These findings suggest that excretion of feces containing more viable B. quintana that is proliferated inside body lice following ingestion of infected blood meal is responsible for the higher vector competence of body lice.
Salmonella enteritis: A Rare Cause of Adult Intussusception
Toan Pham,Domenic La Paglia,Meron Pitcher 대한대장항문학회 2017 Annals of Coloproctolgy Vol.33 No.5
Intussusception is a relatively rare condition in the adult population and is commonly secondary to a malignant process. Eight to twenty percent of cases of adult intussusception are thought to be idiopathic. In children, infection has been proven to precipitate intussusception in the absence of any other cause. We present a rare case of intussusception in a healthy adult patient secondary to salmonella infection and discuss infection as a potential explanation for a proportion of the cases of adult intussusception that are thought to be idiopathic. We recommend testing for infective causes of intussusception in adults when more common causes, such as malignancy, have been excluded.
A hybrid numerical flux for supersonic flows with application to rocket nozzles
Ferrero, Andrea,D'Ambrosio, Domenic Techno-Press 2020 Advances in aircraft and spacecraft science Vol.7 No.5
The numerical simulation of shock waves in supersonic flows is challenging because of several instabilities which can affect the solution. Among them, the carbuncle phenomenon can introduce nonphysical perturbations in captured shock waves. In the present work, a hybrid numerical flux is proposed for the evaluation of the convective fluxes that avoids carbuncle and keeps high-accuracy on shocks and boundary layers. In particular, the proposed flux is a combination between an upwind approximate Riemann problem solver and the Local Lax-Friedrichs scheme. A simple strategy to mix the two fluxes is proposed and tested in the framework of a discontinuous Galerkin discretisation. The approach is investigated on the subsonic flow in a channel, on the supersonic flow around a cylinder, on the supersonic flow on a flat plate and on the flow in a overexpanded rocket nozzle.
Kyu Tae Kim,Domenic Santavicca 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.12
The dynamic response of a turbulent premixed flame to acoustic velocity perturbations was experimentally determined in a swirl-stabilized lean-premixed gas turbine combustor. CH* chemiluminescence intensity and the twomicrophone method were used to measure heat release rates and inlet velocity fluctuations, respectively. Using the n-τ formulation, gain and phase of flame transfer functions were incorporated into an analytic thermoacoustic model to predict instability frequencies and modal structures. Self-excited instability measurements were performed to verify eigenfrequencies predicted by the thermoacoustic model. Instability frequency predicted by the model is supported by experimental results. Results show that the self-excited instability frequency of ~ 220 Hz results from the fact that the flames amplify flow perturbations with f = 150 ~ 250 Hz. The other instability frequency of ~ 350 Hz occurs because the whole combustion system has an eigenfrequency corresponding to the ¼-wave eigenmode of the mixing section.
Ju Hyeon Kim,Kyong Sup Yoon,Domenic J. Previte,Barry R. Pittendrigh,J. Marshall Clark,이시혁 한국응용곤충학회 2012 Journal of Asia-Pacific Entomology Vol.15 No.3
Human body and head lice have been hematophagous ectoparasites of humans for thousands of years. Although both body and head lice belong to a single species, Pediculus humanus, only body lice are known to transmit several bacterial diseases to humans. This difference in vector competence is assumed to be due to their different immune responses. Here, the immune reactions in the alimentary tract were investigated in both body and head lice following oral challenge of Escherichia coli as a model Gram-negative bacterium. In proliferation assay, head lice suppressed the growth of E. coli effectively at the early stage of infection,resulting in gradual reduction of E. coli number in alimentary tract tissues. In contrast, the number of E. coli steadily increased in alimentary tract tissues of body lice. No apparent alteration of transcription was observed following E. coli challenge in three important genes for the humoral immune responses, peptidoglycan recognition protein as a recognition gene and defensin 1 and defensin 2 as effector genes. Nevertheless, the basal transcription levels of these genes were higher in the gut tissues of body versus head lice. Considering that there is no cellular immune reaction in gut tissues, these findings suggest that the higher constitutive transcription levels of major immune genes in head lice can contribute to their rapid defense and enhanced immune capacity against intestinal bacterial infection.
가스터빈 희박 예혼합 연소기에서의 화염의 동적 거동에 관한 연구
김대식(Daesik Kim),이종근(Jong Guen Lee),Domenic Santavicca 한국연소학회 2009 KOSCOSYMPOSIUM논문집 Vol.- No.39
This paper describes the forced flame response in a turbulent premixed gas turbine combustor. The fuel was premixed with the air upstream of a choked inlet to avoid equivalence ratio fluctuations. To impose the inlet flow velocity, a siren type modulation device was developed using an AC motor, rotating and static plates. Measurements were made of the velocity fluctuation in the nozzle using hot wire anemometry and of the heat release fluctuation in the combustor using chemiluminescence emission. The test results showed that flame length as well as geometry was strongly dependent upon modulation frequency in addition to operating conditions such as inlet velocity. Convection delay time between the velocity perturbation and heat release fluctuations was calculated using phase information of the transfer function, which agreed well with the results of flame length measurements. Also, basic characteristics of the flame nonlinear response shown in the current test conditions were introduced.
가스터빈 연소기 난류 비정상 화염으로부터의 화학발광 측정
김대식(Daesik Kim),이종근(Jong Guen Lee),Domenic Santavicca 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.40
The measurement of heat release rate is of great importance in the study of thermo-acoustic instability occurring in lean premixed combustion and the chemiluminescence emission has been used as an indicator of heat release in combustion instability studies primarily for its relative simplicity. This paper presents results of experimental study of flame chemiluminescence from an atmospheric, swirl-stabilized, turbulent lean premixed flame with a main emphasis on the effect of CO2* background level in the CH* and OH* band. The test results show that the effct of CO2* level in the CH* band is greater than that in the OH* band. Also, the background to peak ratio for both CH* and OH* bands can be expressed as a function of equivalence ratio, almost regardless of a change in the inlet velocity.