8 results
Effects of strain on the resonant Raman profile of metallic
- Antonio G Souza Filho, N Kobayashi, Jie Jiang, Riichiro Saito, Stephen B Cronin, Josue Mendes Filho, Ge G Samsonidze, Gene Dresselhaus, Mildred S Dresselhaus
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- Journal:
- MRS Online Proceedings Library Archive / Volume 901 / 2005
- Published online by Cambridge University Press:
- 26 February 2011, 0901-Rb24-04
- Print publication:
- 2005
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In this paper we report the effects of strain on the electronic properties of single wall carbon nanotubes and its consequence on the resonant Raman cross section. A quantum interference effect has been predicted for the radial breathing mode spectra for metallic tubes. For metallic tubes, the lower and upper components of Eii resulting from the trigonal warping effect are affected differently and for low chiral angle they cross for some strain value. Near (at) the crossing point, the resonant Raman spectra profile exhibits a maximum (minimum) value due to a quantum interference in the Raman cross section. This Raman cross section interference effect was observed in Raman experiments carried out on isolated SWNTs. The Raman experiment performed on an isolated strained metallic SWNT supports our modeling predictions.
8 - The Role of Imaging in the Follow-up of SARS
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- By GE Antonio, KT Wong, DSC Hui, AT Ahuja
- Edited by A. T. Ahuja, The Chinese University of Hong Kong, C. G. C. Ooi, The Chinese University of Hong Kong
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- Book:
- Imaging in SARS
- Published online:
- 27 October 2009
- Print publication:
- 24 June 2004, pp 79-88
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Summary
Introduction
Severe acute respiratory syndrome (SARS) has shown itself to be different from most other forms of viral pneumonia in its infectivity, clinical course, predilection for affecting health care workers, and high rates of mortality and morbidity. During the acute phase of the epidemic the imaging characteristics of SARS during the acute phase been investigated, but its post-treatment sequelae are only just becoming apparent as they surface in the imaging of patients attending follow-up. In line with the acute stages of this disease, the recovery also appears to be punctuated with an exaggeration of the host response, with patients developing residual disease or early signs of fibrosis in affected areas of the lungs. With this in mind, the follow-up of these patients will require close clinical and radiological monitoring. This chapter shall present the appearances and role of imaging in the follow-up of SARS.
Follow-up presentation of SARS patients
Follow-up is usually uneventful for most other types of viral pneumonia in adults. However, while a portion of treated and discharged SARS patients may be completely asymptomatic, a significant number have residual symptoms. It has been reported that 46% of discharged patients complained of exertional dyspnoea at 1-month follow-up. This was not restricted to elderly patients but also affected patients in their 30s, resulting in the limitation of their daily activities.
6 - Chest Radiography: Clinical Correlation and Its Role in the Management of Severe Acute Respiratory Syndrome
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- By DSC Hui, KT Wong, GE Antonio, AT Ahuja, JJY Sung
- Edited by A. T. Ahuja, The Chinese University of Hong Kong, C. G. C. Ooi, The Chinese University of Hong Kong
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- Book:
- Imaging in SARS
- Published online:
- 27 October 2009
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- 24 June 2004, pp 61-68
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Summary
Introduction
Chest radiography (CXR) not only plays an important role in the diagnosis of severe acute respiratory syndrome (SARS), it is crucial in the management of these patients. During treatment there are variable clinical and radiological responses in different patients and serial CXR help in deciding whether escalation to more aggressive treatment is necessary.
Based on our preliminary experience, we believe that changes on serial radiographs is also an important prognostic indicator.
This chapter aims to examine the correlation between the clinical course and the radiological features, and the role of CXR in the management of SARS.
Treatment protocol
The treatment of SARS patients is discussed in detail in a separate chapter (see Chapter 9). However, in order to better understand the clinical and radiological correlation one must be familiar with the basic treatment principles. These are therefore discussed briefly in the following paragraph.
Patients were treated for the first 2 days with broad-spectrum antibiotics for community-acquired pneumonia according to the American Thoracic Society Guidelines. Our initial treatment consisted of intravenous (IV) cefotaxime 1 g every 6 hours and oral clarithromycin 500 mg twice daily (or oral levofloxacin 500 mg daily for those who could not tolerate clarithromycin).
Clinical symptoms, arterial blood oxygen saturation and CXR were assessed daily.
10 - SARS in the Intensive Care Unit
- Edited by A. T. Ahuja, The Chinese University of Hong Kong, C. G. C. Ooi, The Chinese University of Hong Kong
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- Book:
- Imaging in SARS
- Published online:
- 27 October 2009
- Print publication:
- 24 June 2004, pp 99-108
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Summary
Introduction
Severe acute respiratory syndrome (SARS) is clinically severe with a high proportion of cases, approximately 20%, requiring intensive care unit (ICU) admission. The provision of organ support in the ICU therefore plays a potentially important role in reducing mortality, which may be as high as 10% for younger patients and 50% for patients older than 60 years. Radiological imaging of the chest is important because of the overriding importance of respiratory failure in determining the management and outcome of SARS.
At the time of writing there were little published data detailing the ICU management and outcome of SARS, and much the information that follow are based on the observational data derived from our institution.
ICU admission
Patients generally present to the hospital with fever, chills, rigors, myalgia, headache and a non-productive cough. Common laboratory features include an elevated serum lactate dehydrogenase (LDH) concentration, lymphopaenia, hypocalcaemia and moderate thrombocytopaenia. SARS is a slowly progressive disease and the average interval from the onset of symptoms to requirement for ICU admission is approximately 10 days. Clinical deterioration of cases admitted to the ward is manifested by progressive hypoxia and dyspnoea, and is accompanied by progression of pulmonary infiltrates on chest radiograph. Close monitoring of disease progress in the general wards is therefore important to detect deterioration in those patients who will be admitted to ICU.
7 - The Role of High-Resolution Computed Tomography in Diagnosis of SARS
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- By GE Antonio, KT Wong, DSC Hui, AT Ahuja
- Edited by A. T. Ahuja, The Chinese University of Hong Kong, C. G. C. Ooi, The Chinese University of Hong Kong
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- Book:
- Imaging in SARS
- Published online:
- 27 October 2009
- Print publication:
- 24 June 2004, pp 69-78
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Summary
Introduction
Plain radiography and high-resolution computed tomography (HRCT) are the cornerstones for imaging the lungs. HRCT is capable of imaging the lungs with excellent spatial resolution, providing anatomical detail similar to that available from gross pathological specimens or lung slices. It is especially good for the early detection and characterization of localized or diffused lung parenchymal abnormalities. However HRCT involves a high-radiation dose, is not readily available and therefore may not be suitable as the first line of investigation for suspected severe acute respiratory syndrome (SARS) patients or in a screening role in endemic/pandemic situation. In such a situation, HRCT should be reserved for selected group of patients with good clinical indication and non-diagnostic chest radiograph (CXR). The indications should be more relaxed with sporadic cases. The diagnostic protocol for imaging and the use of CXR and HRCT have been discussed previously (Figure 7.1).
Apart from diagnosis, HRCT also plays an important role to monitor progress and response to treatment and for follow-up. These will be dealt with separately in later chapters. This chapter aims to give the reader an insight about the role of HRCT in diagnosis of SARS and to describe various radiological appearances on HRCT.
17 - Update on Severe Acute Respiratory Syndrome
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- By AT Ahuja, GE Antonio
- Edited by A. T. Ahuja, The Chinese University of Hong Kong, C. G. C. Ooi, The Chinese University of Hong Kong
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- Book:
- Imaging in SARS
- Published online:
- 27 October 2009
- Print publication:
- 24 June 2004, pp 165-174
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Summary
Introduction
The passage of time has healed some of the wounds inflicted by the deadly epidemic. The economy in Hong Kong and most of Asia has picked up and the communities have gone back to their daily activities. The masks and the gloves are off and people have gone back to their old habits with respect to personal hygiene and work practices. After all, old habits die hard.
However, severe acute respiratory syndrome (SARS) continues to lurk in the background and still causes a diagnostic dilemma. By the end of 2003/early 2004 (at the time of writing this chapter), there were five sporadic cases of SARS, two involving laboratory researchers and three outside the laboratory in Guangdong Province in China. Although the two laboratory cases (Taiwan, Singapore) were readily identified, the cases in Guangdong were definitively verified more than a week after the suspicion was raised. The clinical parameters, laboratory tests and history of contact in this patient were initially nebulous, highlighting the difficulty in the early diagnosis of this potentially fatal disease. Despite detailed contact, tracing the source of the infection was not definitively traced and it has been postulated that the source might have been civet cats as unpublished reports from Guangdong and Hong Kong have found similarities in the genetic sequences of the virus in the SARS patient and civet cats, which is a gourmet delicacy in southern China.
5 - The Role of Chest Radiographs in the Diagnosis of SARS
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- By KT Wong, GE Antonio, EHY Yuen, AT Ahuja
- Edited by A. T. Ahuja, The Chinese University of Hong Kong, C. G. C. Ooi, The Chinese University of Hong Kong
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- Book:
- Imaging in SARS
- Published online:
- 27 October 2009
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- 24 June 2004, pp 53-60
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Summary
Introduction
At the onset of the severe acute respiratory syndrome (SARS) crisis, the majority of patients were presented with respiratory symptoms. As the epidemic progressed, either due to a different mode of transmission or a mutation of the virus, some SARS patients presented with minor or no respiratory symptoms but diarrhoea. Understandably, this created a problem with case definition and diagnosis, and the lack of a reliable and rapid biochemical test for SARS placed more emphasis on chest imaging findings for diagnosis of the disease.
The wide availability, speed and inexpensive nature of the chest radiograph (CXR) has made it the first-line imaging investigation when faced with a respiratory complaint. It is only fitting that the initial imaging investigation of SARS also starts here. This chapter presents the radiographic features of SARS and the differential diagnosis.
Pathological considerations
Viral infection of the respiratory tract may involve the upper system, from the common cold (rhinoviruses and coronaviruses), larynx (respiratory syncitial virus), trachea and bronchi (herpes simplex type 1) to the lung parenchyma (influenza). The initial phase in viral lung parenchymal involvement is called a pneumonitis. A local inflammatory response is directed towards the offending virus, an inflammatory cocktail of cells and fluid accumulate in the alveolar interstitium of the lung parenchyma. In bacterial infections this exudate spills over into the airspace and results in the classic consolidation.
16 - Aftermath of SARS
- Edited by A. T. Ahuja, The Chinese University of Hong Kong, C. G. C. Ooi, The Chinese University of Hong Kong
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- Book:
- Imaging in SARS
- Published online:
- 27 October 2009
- Print publication:
- 24 June 2004, pp 159-164
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Summary
Introduction
This chapter briefly examines:
the weaknesses in the health care systems exposed by the severe acute respiratory syndrome (SARS) epidemic in Hong Kong,
the sequelae of the disease.
Audits
Two audit committees, set up by the Hong Kong Government and Hospital Authority respectively, reviewed the response of the health systems to the SARS epidemic. The findings of both audits were similar. The main criticism were that:
Government agencies were not prepared for an outbreak of such magnitude. Procedural mechanisms were not in place beforehand so agencies were always trying to catch up.
Information about an unusual viral infection in early February 2003 only had the status of rumour and early ‘soft’ evidence was neglected.
Not enough was done early in the epidemic to alert other hospitals and health care workers of potential risks. And when information was disseminated it was not very clearly communicated.
The following recommendations were made:
Effective surveillance, data collection and sharing
High level of awareness and implementation of effective infection control measures.
Rapid and comprehensive contact tracing.
Timely declaration and enforcement of isolation and quarantine measures.
Both the audits were comprehensive, clearly identified the deficiencies and made suitable recommen dations for future improvement.