Dscussion应该最能体现一个人学术critical thinking的能力了,跟原来的Merit的论文对比,我觉得我好像开窍了,我好像悟到老师想要啥了！只要Discussion写得好,1st不是梦! 话不多说直接上干货！需要Discussion代写请联系英国论文代写。
Higher residential concentrations of O3, PM2.5, and NOx at study baseline, of black carbon averaged from 2006 to 2008, and of O3 and NOx assessed over study follow-up were significantly associated with greater increases in percent emphysema, assessed via CT imaging, over a median of 10 years. Findings were most robust and of greatest magnitude for O3. Because percent emphysema is related to respiratory symptoms, hospitalizations,7 and mortality even among individuals without airflow obstruction,4,6 these associations in a community-based population demonstrate novel evidence that air pollution contributes to worsening lung health.
Despite existing regulations to prevent short-term excursions of O3 levels, long-term average concentrations of O3, which were associated with changes in lung structure and function, did not decline during the years of observation. Absent new control strategies, these levels are not expected to decline as climate change advances. 25 This contrasts with the observed trends in PM2.5 and NOx that highlight the success of past regulatory initiatives to control these 2 pollutants. Because long-term concentrations of O3 at current levels were strongly and consistently associated with both progression of emphysema and decline in lung function in this study, more effective control strategies to reduce O3 concentrations may be needed to protect lung health.
Ground-level O3 is a powerful oxidizing agent and common air pollutant worldwide.Toxicologic studies have shown that O3 causes persistent pulmonary inflammation and structural alterations throughout the lung that may play a role in chronic lower respiratory disease, including emphysema.26 In a mouse model, exposure to O3 for 6 weeks induced a chronic inflammatory process, with increased protease expression, epithelial apoptosis and alveolar enlargement, and destruction, mimicking emphysema.27 In animals, PM2.5 exposure leads to neutrophili pulmonary inflammation and oxidative stress,28 and in healthy adults, controlled exposure to PM2.5 leads to increased systemic inflammation and endothelial microparticles, including those of lung origin.29 This may be relevant because endothelial apoptosis causes emphysema in animals and endothelial microparticles have been linked to lower lung function and, specifically, percent emphysema in individuals with mild COPD and smokers without COPD.30
The current study found that faster progression of percent emphysema and decline in FEV1 were significantly associated with long-term O3 concentrations among the subset of participants with airflow limitation at baseline. This finding is consistent with prior studies demonstrating worse outcomes related to air pollution in patients with lung disease31 and supports the conclusion in the 2013 EPA Integrated Science Assessment that individuals with lung disease are a high risk group for O3-related health effects.32
- This finding was consistent with prior studies…；
- Consistent with the prior studies , our study indicated/showed that…；
- Our findings were in line with the prior studies…
Findings for O3 and loss of lung function were greater among current smokers, perhaps because of additive effects of airway inflammation and oxidative stress.33
Higher exposures to PM2.5 and NOx at baseline and NOx (and no other pollutants) over follow-up were also significantly associated with faster emphysema progression. When all pollutants were considered together, there was evidence that the association for O3 was of the greatest magnitude, which is consistent with other literature,12 and for an additive effect of copollutants, which is consistent with animal studies.33
Unlike O3 and NOx, PM2.5 exposure over follow-up was not significantly associated with emphysema progression. Development of emphysema can be a slow, lifelong process and, once initiated, additional areas of emphysema in the adjacent lung can be produced from biomechanical forces, even in the absence of further exposures, such as cigarette smoke.34 These findings might explain the increased rate of emphysema progression significantly associated with PM2.5 at baseline but not during follow-up. Baseline measures likely reflect exposure at and prior to baseline, particularly for PM2.5 concentrations, which declined substantially over the 10 years of follow-up. In addition, the changes in scanner technology over follow-up as PM2.5 concentrations decreased may have made the follow-up analyses less sensitive for emphysema progression than the baseline analyses。
While O3 exposure was significantly associated with decline in lung function, the other pollutants were not; statistical power for spirometry was smaller than for percent emphysema on CT because the number of observations for spirometry were less than half those for percent emphysema and occurred during the latter period of follow-up when nonozone pollutant concentrations had declined. While air pollutants, including O3, PM2.5, NOx, and black carbon, have been associated consistently with respiratory events,10,12 relatively few studies have reported a longitudinal association between O3, PM2.5, and NOx and decline in lung function in older adults, and findings have not been completely consistent. Single site studies have reported longitudinal associations between PM2.513 and black carbon35 and a faster decline in lung function, and a larger multi-center study in Europe found PM10 to be associated with a faster lung function decline.36 However, another large European study did not find any longitudinal associations between air pollutants and lung function decline.37
To our knowledge, this is the first longitudinal study to assess the association between long-term exposure to air pollutants and progression of percent emphysema on CT in a large, community-based multiethnic cohort.
阐述研究的主要优势，对于首例研究的表达需谨慎，只要在查询大量文献后，确保事实如此，才用 first XX study to assess/investigate…. 表达。
Other strengths of this study include the large sample size, the long period of follow-up, and the fine-scale assessment of residential level outdoor air pollution concentrations from cohortspecific monitoring and advanced statistical modeling.
其他研究优势的说明，讨论部分中阐述优缺点时，可以采用 there are several strengths in our study, Firstly… Secondly, Another strength… Lastly… 等固定套路。
This study has several limitations. First, outdoor air pollution concentrations, especially in the case of O3, may not fully reflect individual air pollution exposures and dose in all microenvironments38; outdoor concentrations do not explain all variation in indoor concentrations, and most individuals spend the majority of their time indoors.39 Second, percent emphysema was measured only in the lower two-thirds of the lung. However, percent emphysema measured in the lower two-thirds of the lung correlates well with full-lung percent emphysema (ICC, 0.93) in this cohort and a cohort of smokers,18 and percent emphysema measured on cardiac scans was associated with dyspnea, spirometric obstruction, and mortality in this cohort.4,8 Third, CT scanners changed over the 18 years of data collection; however, analyses using an advanced image processing approach designed to account for scanner variation yielded similar results, as did sensitivity analyses using various approaches to adjust for stratification by scanner type (eTables 4 and 5 in the Supplement). There is debate about the optimal parameterization of the histogram of the lung attenuation; however, sensitivity analyses using PD15 yielded consistent results. Fourth, no volume correction of CT data was performed,40 given the debate over its utility and the partial lung imaging; however, results were consistent when participants with a difference greater than 20% in lung volume on CT scans were excluded.
接下来，和大家分享下 Discussion 的几点注意事项：
1. Discussion 部分写作，所有数据都要源于论文的 Results，不能引入新的数据。当然，引用他人的文献除外，但不要过于重复 Results 内容。
2. Discussion 要特别注意逻辑性，很多作者写经常跑偏了。应按照结果的主次进行分段讨论，讲述每个结果表示什么，与前人发表的数据对比，引证文献加以说明。
3. Discussion 中应正视研究的不足。像 LANCET，NEJM，JAMA 这些顶刊作者也会在论文中相当谦虚的说明研究的局限，对未来可以改进的地方进行讨论和展望，化被动为主动，建议大家学习。
4. 写 Discussion 语法上尽量使用主动句，语句要简练。
总结一下，本文以 JAMA 发表的文章为例，向大家分享了 SCI 论文 Discussion 的写作，建议作者在平时多写多练，不断提升科研写作能力！
1,简洁概括本文的key findings/results:最好按照first, .second, .third,最好分条陈述。
3. Theoretical implications:你研究出来的这些东西在理论和学术上有什么意义。
4, Empirical implications:你研究出来的这些东西对现实世界有什么意义:可以是对你的研究对象company/industry/stakeholders 也可以是为政府提供政策支持等等。
5. Limitations:你的研究方法和结论有哪些局限。比如说boundary conditions:你的结论在什么情况下成立,什么情况下可能不成立;因为不可能某一个finding对所有情况和对象都适用。一般可以写个三四条。