Interpreting Dose-Response Relation for Exposure to Multiple Sound Impulses in the Framework of Immunity

Hearing loss is a common military health problem and it is closely related to exposures to impulse noises from blast explosions and weapon firings. In a study based on test data of chinchillas and scaled to humans (Military Medicine, 181: 59-69), an empirical injury model was constructed for exposure to multiple sound impulses of equal intensity. Building upon the empirical injury model, we conduct a mathematical study of the hearing loss injury caused by multiple impulses of non-uniform intensities. We adopt the theoretical framework of viewing individual sound exposures as separate injury causing events, and in that framework, we examine synergy for causing injury (fatigue) or negative synergy (immunity) or independence among a sequence of doses. Starting with the empirical logistic dose-response relation and the empirical dose combination rule, we show that for causing injury, a sequence of sound exposure events are not independent of each other. The phenomenological effect of a preceding event on the subsequent event is always immunity. We extend the empirical dose combination rule, which is applicable only in the case of homogeneous impulses of equal intensity, to accommodate the general case of multiple heterogeneous sound exposures with non-uniform intensities. In addition to studying and extending the empirical dose combination rule, we also explore the dose combination rule for the hypothetical case of independent events, and compare it with the empirical one. We measure the effect of immunity quantitatively using the immunity factor defined as the percentage of decrease in injury probability attributed to the sound exposure in the preceding event. Our main findings on the immunity factor are: 1) the immunity factor is primarily a function of the difference in SELA (A- weighted sound exposure level) between the two sound exposure events;it is virtually independent of the magnitude of the two SELA values as long as the difference is fixed;2) the immunity factor increases monotonically from 0 to 100% as the first dose is varied from being significantly below the second dose, to being moderately above the second dose. The extended dose-response formulation developed in this study provides a theoretical framework for assessing the injury risk in realistic situations.

Effect of Short-Term Exposure to Mercuric Chloride on the Air-Breathing Catfish,Heteropneustes fossilis──Ⅱ.Scanning Electron Microscopic Study of the Gill

Alterations in the respiratory epithelium of gills of a catfish, Heteropneustes fossilis by the sublethal and lethal concentrations of HgCl2 have been observcd using scanning electron microscope. Fish exposed to 0.1 ppm shows a thin coat ot mucus, but the continuous layer of mucus is not retained in 0.3 ppm after 24 h of exposure. Epithelial cells of the gill filament are hyperplastic. Other changcs in the respiratory epithelium are contraction of epithelium, formation of interlamellar bridge and diminishing number of microridges. Massive destruction of the respiratory epithelium by deep lesions and sloughing of epithelial layer in 0.5 and 1.0 ppm solutions after 6-12 h of exposure apparently causes death to the fish. SEM observations are well in conformity with the findings made at light microscopic level

Verification on the Developmental Toxicity of Short-term Exposure to Phenol in Rats

Objective To verify the health advisory for short-term exposure to phenol.Methods The method of this validation experiment was the same as the US Environmental Protection Agency(EPA)methodology for toxicology experiments used to determine phenol drinking water equivalent level(DWEL).Pregnant female Sprague-Dawley rats were administered phenol in distilled water by gavage at daily doses of 15,30,60,120,and 240 mg/kg body weight(b.w.)from implantation(the 6 th day post-mating)to the day prior to the scheduled caesarean section(the 20th day of pregnancy).The following information was recorded:general behavior;body weight;number of corpus luteum,live birth,fetus,stillbirth,and implantation;fetal gender;body weight;body length;tail length;and abnormalities and pathomorphological changes in the dams.Results In the 60 mg/kg b.w.dose group,the mortality of pregnant rats increased with increasing doses,suggesting maternal toxicity.Fetal and placental weights decreased as phenol dose increased from30 mg/kg b.w.,and were significantly different compared those in the vehicle control group,which suggested developmental toxicity in the fetuses.However,the phenol-exposed groups showed no significant change in other parameters compared with the vehicle control group(P>0.05).Conclusion Despite using the same method as the US EPA,a different NOEAL of 15 mg/(kg·d)was obtained in this study.

Effect of Short-Term Exposure to Mercuric Chloride on the Air-Breathing Catfish,Heteropneustes fossilis──Ⅰ.Light Microscopic Study of the Gill

Histopathological effects of sublethal (0.1, 0.2, 0.3 ppm) and lethal (0.5, 1.0 ppm)solutions of mercuric chloride (HgCl2) have been studied on the gills of the air breathing catfish, Heteropneustes fossilis at the intervals ranging from 6h to 15 days. Thickening of the epithelium, swelling and hyperplasia of the mucous cells, fusion of secondary lamellae, formation of interlamellar bridge and deposition of mucous over the entire surface are some noteworthy features of mercury poisoning in sublethal concentrations. Acute pathological manifestations are formation of subepithelial space, sloughing of the epithelial layer, hemorrhage and hypertrophy of the mucous cells. Causes and impact of these cellular alterations affecting survival of the fish have been discussed

Sick Neighborhood Syndrome: Population with Multiple Chemical Sensitivity Adjacent to Bioethanol Distillery

The population of a neighborhood in the city of Córdoba presents general irritant symptoms since a bioethanol distillery began to operate there, from which formaldehyde, toluene, xylene mainly emanate. At the request of the community, collective environmental health was evaluated with a cross-sectional study of prevalence of these conditions. 53% of the residents reported respiratory disorders, conjunctivitis 31%, headaches 27%, dermatitis 23% and dyspepsia 22%. 57% of children aged 6 - 7 use bronchodilators (an indicator of asthma). 66% of the population has one of these conditions, 46% has two and 26% has three;children are the most affected. The results coincide with the Consensus on Multiple Chemical Sensitivity Syndrome in that it is reproducible by repeated chemical exposure, is chronic and does not improve without eliminating exposure, affecting multiple organs and systems. 14.8% of newborns feature malformations, while in the rest of the city, only 1.7% did. Similar to the Sick Building Syndrome, the collective health picture found suggests a “Sick Neighborhood Syndrome”.

The Determinants of Risk Exposure When Development Finance Institutions Consider Approval of Funding to Different Development Markets—Case Study Development Bank of Southern Africa

This paper evaluates the determinants of risk exposure when development finance institutions consider approval of funding to different development markets utilising multiple regression econometric models and the Development Bank of South Africa(DBSA)as a case study.The research presents the classical development finance institution(DFI)business model and market size estimation with the contemporary DFI risk classification and enterprise risk management framework.In addition to reviewing the profile of financial and non-financial products and services,the related project cycles and the DFI credit risk pricing and mitigation approaches for the different development markets.Our results suggest that there is a correlation between the funding of under-resourced municipalities by DBSA and its exposure to financial risk though the correlation is not overwhelmingly significant,but also evidence of a negative correlation between the funding of under-resourced municipalities and the minimization of the financial risk exposure of DBSA.Likewise,there is a negative correlation between funding to all three different sizes of a municipality and ability of the DFI to absorb future losses(non-performing loan coverage ratio).The negative correlation is highest for secondary cities followed by metros and least for under resourced municipalities.The research concludes with four major recommendations of what the role of the DFI should be in enhancing access of under-resourced municipalities to development funding.

Real-World Evidence of Multiple Air Pollutants and Mortality:A Prospective Cohort Study in an Oldest-Old Population

We aimed to report real-world longitudinal ambient air pollutants levels compared to WHO Air Quality Guidelines(AQG)and analyze multiple air pollutants’joint effect on longevity,and the modification and confounding from the climate and urbanization with a focus on the oldest-old.This study included 13,207 old participants with 73.3%aged 80 and beyond,followed up from 2008 to 2018 in 23 Chinese provinces.We used the Cox-proportional hazards model and quantile-based g-computation model to measure separate and joint effects of the multiple pollutants.We adjusted for climate and area economic factors based on a directed acyclic graph.In 2018,no participants met the WHO AQG for PM_(2.5) and O_(3),and about one-third met the AQG for NO_(2).The hazard ratio(HR)for mortality was 1.07(95%confidence interval-CI:1.05,1.09)per decile increase in all three pollutants,with PM_(2.5) being the dominant contributor according to the quantile-based g-computation model.In the three-pollutant model,the HRs(95%CI)for PM_(2.5) and NO_(2) were 1.27(1.25,1.3)and 1.08(1.05,1.12)per 10μg/m3 increase,respectively.The oldest-old experienced a much lower mortality risk from air pollution compared to the young-old.The mortality risk of PM_(2.5) was higher in areas with higher annual average temperatures.The adjustment of road density considerably intensified the association between NO_(2) and mortality.The ambient PM_(2.5) and O_(3) levels in China exceeded the WHO AQG target substantially.Multiple pollutants coexposure,confounding,and modification of the district economic and climate factors should not be ignored in the association between air pollution and mortality.

老年共病患者心理危机自我表露阻碍和促进因素的质性研究

目的 深入探究老年共病患者心理危机表露的阻碍和促进因素,为促进老年患者面临心理危机时的自我表露提供依据。方法 采用现象学研究方法,访谈14例老年共病患者。结果 阻碍因素包括个人因素(内向/隐忍型性格、担心给家人带来困扰、对生命状态的负性心理)和动机因素(消极反馈、认知缺乏、时间弱化),促进因素包括感知表露后益处、良好的支持系统、个人表达意愿强。结论 老年共病患者心理危机表露存在阻碍和促进因素,应通过让患者感知表露后益处、给予良好的支持系统、丰富多种表露途径、加强患者对心理危机的认知等措施来促进老年共病患者主动表露其心理危机。

Short-term intravenous interferon therapy for chronic hepatitis B

AIM:To investigate the therapeutic efficacy of short- term, multiple daily dosing of intravenous interferon (IFN) in patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B. METHODS:IFN-β was intravenously administered at a total dose of 102 million international units (MIU) over a period of 28 d in 26 patients positive for HBeAg and HBV-DNA. IFN-beta was administered at doses of 2 MIU and 1 MIU on d 1, 3 MIU twice daily from d 2 to d 7, and 1 MIU thrice daily from d 8 to d 28. Patients were followed up for 24 wk after the end of treatment. RESULTS:Six months after the end of the treatment, loss of HBV-DNA occurred in 13 (50.0%) of the 26 patients, loss of HBeAg in 9 (34.6%), development of anti-HBe in 10 (38.5%), HBeAg seroconversion in 8 (30.8%), and normalization of alanine aminotransferase (ALT) levels in 11 (42.0%). CONCLUSION:This 4-wk long IFN-β therapy, which was much shorter than conventional therapy lasting 12 wk or even more than 1 year, produced therapeutic effects similar to those achieved by IFN-α or pegylated- IFN-α (peg-IFN). Fewer adverse effects, greater efficacy, and a shorter treatment period led to an improvement in patients’ quality of life. IFN-β is administered intravenously, whereas IFN-α is administered intramuscularly or subcutaneously. Because both interferons are known to bind to an identical receptor and exert antiviral effects through intracellular signal transduction, the excellent results of IFN-β found in this study may be attributed to the multiple doses allowed by the intravenous route.

Experimental Research on Multi-Wavelength FBG Fabrication Based on Multiple Exposure

A fabrication method of the multi-wavelength fiber grating （FBG） was introduced. Using the scan exposure method, the multi-wavelength FBG can be successfully manufactured through applying different tensile forces during the multiple exposures process on the same fiber. Experiment results show that the position and the overlap of different sub FBGs will greatly affect the spectrum of every sub FBG. The spectrum of each sub FBG will be affected by short wave oscillation unless the lengths and positions of all sub FBGs are fully overlapped. For hydrogen loaded fiber, the wavelength and reflectivity of the nth level FBG will increase as the （n＋1）th level FBG is written. But for germanium doped photosensitive fiber, multiple exposure will increase the wavelength of previous sub FBGs while decrease the reflectivity of all sub FBGs. Through well distributing exposure intensity of every sub FBGs, a four-wavelength FBG with same sub FBG＇s spectrtLrn was fabricated on a hydrogen loaded single mode fiber.

Synthesizing monochromatic 3-D images by multiple-exposure rainbow holography with vertical area-partition approach

We report for the first time the theoretical analysis and experimental results of a white-light reconstructed monochromatic 3-D image synthesizing tomograms by multiple rainbow holo-graphy with vertical-area partition (VAP) approach. The theoretical and experimental results show that 3-D monochromatic image can be synthesized by recording the master hologram by VAP ap-proach without any distortions either in gray scale or in geometrical position. A 3-D monochromatic image synthesized from a series of medical tomograms is presented in this paper for the first time.

基于去尘估计和多重曝光融合的煤矿井下图像增强方法

煤矿井下粉尘和暗光等因素导致采集的图像质量低,而现有图像增强方法存在图像细节丢失、局部特征不清晰、无法消除噪声、去尘效果不理想等问题。针对上述问题,提出了一种基于去尘估计和多重曝光融合的煤矿井下图像增强方法。该方法通过尘化图像简易模型及暗原色理论,并引入自适应衰减系数估算出图像透射率,再根据透射率分布,通过尘化图像简易模型复原物体的原始图像,将煤矿井下图像中的粉尘去除;利用多重曝光融合算法为曝光不足的原始图像生成一组不同曝光比的图像,并引入权值矩阵将这些不同曝光比的图像与原始图像进行融合,有效提升暗光图像质量。实验结果表明:相较于直方图均衡法、带色彩恢复的Retinex(MSRCR)方法、改进Retinex方法,该方法在去尘及暗光增强方面效果较好,颜色还原度较高,白边和过曝等现象得到抑制,且增强后的图像平均对比度分别提升了169.00%,42.50%,10.88%,平均图像熵分别提升了51.80%,16.45%,8.99%,平均亮度顺序误差(LOE)分别降低了31.01%,16.94%,7.83%,同时该方法运算耗时最短。

基于信度评估的线结构光多重曝光条纹提取

在单线结构光三角测量法的实际应用中,图像中条纹截面灰度分布的可靠性是保证条纹中心提取精度的重要基础。在物体表面反射特性不均匀的测量场景中,受欠曝光与过曝光的双重影响,造成条纹截面灰度分布不均匀、条纹中心可信度低等问题。基于上述问题,对复杂反射特性表面的单线结构光条纹提取技术进行了研究。提出了一种基于信度评估的条纹提取方法。创新性地应用了条纹能量密度与条纹宽度相结合的双参数评价标准,有效避免了单一能量信度标准下约束力不够的问题。该方法依据信度阈值识别多重曝光图像中的可信条纹,并将可信条纹拼接重建成最终条纹图像。试验结果表明,重建图像具有全局可信度,有效提升了条纹中心计算精度。该方法能够为复杂场景下三维测量技术的发展提供一定参考。

越轨同伴交往和暴力媒体接触及攻击规范信念对青少年欺负行为的作用

目的探讨越轨同伴交往(DPA)、暴力媒体接触(EVM)及攻击规范信念(NBA)对青少年欺负行为的作用。方法选取777名中学生为研究对象,采用DPA、EVM、NBA量表及青少年欺负问卷调查中学生的DPA、EVM、NBA及青少年欺负行为情况,采用Pearson相关分析上述4个内容的相关性,结合PROCESS模型6检验DPA、EVM和NBA对青少年欺负行为的影响,并检验EVM和NBA在DPA和青少年欺负行为之间的作用。结果DPA与EVM、NBA和青少年欺负行为之间两两正相关(P<0.01);DPA对青少年欺负行为的直接效应显著(β=0.20,95%CI为0.22~0.35),EVM和NBA在DPA与青少年欺负行为之间的3条中介路径均有统计学意义(总中介效应值为0.09、占比31.36%,95%CI为0.06~0.12)。结论EVM和NBA分别在DPA和青少年欺负行为之间起中介作用,且存在DPA、EVM、NBA、欺负行为的链式效应。

接触内外照射的放射职业人员健康状况对比研究

目的 对长期接触低剂量电离辐射的工作人员进行辐射流行病学调查 ,对单纯接触X射线与接触多种射线的工作人员健康状况进行对比研究 ,为保障放射职业工作人员的健康和辐射安全管理提供科学依据。方法 按照《放射工作人员健康管理规定》中的要求 ,对广东省 999名放射职业人员的进行健康检查并对资料进行统计分析。结果 接触多种放射线 (既接触X射线同时又接触α射线、β射线、γ射线等 )与单纯接触X射线的职业人员在眼晶状体混浊率、血小板计数、外周血淋巴细胞微核率、甲状腺激素水平等方面比较 ,差异有显著性。结论 接触混合射线比单纯接触X射线对健康的影响大 ,因此 。

一种应用于高动态范围CMOS图像传感器的曝光控制技术

针对提高CMOS图像传感器的动态范围,提出了一种新的组合滚筒式曝光技术。由目前现有的技术可知,多次滚筒式曝光一般选择在单帧的时间周期内完成。根据不同的曝光参数,CMOS图像传感器芯片输出不同的图像,然后再将其组合成一帧宽动态范围的图像作为最后输出。本文提出的方法,通过充分利用滚筒式曝光时的空闲电路资源,有效地缩短了相邻图像间的时间间隔。这种方法将多次滚筒式曝光穿插进行,实现对目标图像的多次成像,从而有效提高了系统效率和输出响应速度。

国内外累积性环境风险评估研究进展

随着环境风险评估的重点由单一源、单一传播途径、单受体转向多来源、多传播途径、多受体的评估,累积性环境风险评估逐渐成为当前研究热点。通过概念辨析和文献调研的方法,综述了美国累积性环境风险评估的发展历史、评估流程,并对国内外累积性环境风险评估方法、应用研究进展进行了评述。指出了目前国内开展累积性环境风险评估存在的方法不完善、基础科研工作不足、宏观环境管理政策亟待加强等问题。建议应尽快明确累积性环境风险评估概念与管理要求,制订累积性环境风险评估的流程、框架与技术指南,加强基础数据库建立和实践探索,为长效的环境风险管理提供决策依据。

基于信度评价的焊缝结构光自适应多次曝光法

利用线结构光主动视觉法获取焊缝尺寸时,被测工件表面的复杂特性会造成局部图像质量下降,严重干扰焊缝尺寸计算.针对此问题提出了一种基于信度评价的自适应多次曝光法.将光条的信度评价作为结构光图像的质量评价参数,根据光条的信度分布自动获得下一次拍摄的曝光参数并判断拍摄结束节点.结果表明,基于信度评价的焊缝结构光自适应多次曝光法应用于角焊缝尺寸检测,具有良好的测量稳定性与测量精确度,并且可以有效避免光条图像质量退化造成的测量误差和测量数据缺失.

上海市油漆工苯职业接触浓度矩阵的建立

[目的]根据上海市工作场所化学危害因素监测资料库中油漆工接触苯的监测资料,建立上海市油漆工苯职业接触浓度矩阵(Job-Exposure Matrix,JEM)。[方法]运用Excel2003,Access2003和STATA8.0软件对油漆工接触苯的监测资料作整理、分析、回归和推算。该资料库中1954～2000年油漆作业苯职业接触的数据共37765项,将数据压缩归并两次,通过日平均数值,求取以时段、行业级别和工种级别三者分类交叉归并后的59个浓度均值;再求得对数浓度均值与时段、行业级别和工种级别之间的回归方程式。采取哑变量与样品数权重修饰的方法使回归式更好地拟合。结果][上海市油漆工接触苯浓度矩阵由9个时段、4个行业级别和2个工种级别的72个浓度值组成。[结论]以上海市工作场所化学危害因素监测资料库中的油漆工接触苯的监测资料为基础,运用统计方法,可以建立相应的工种接触浓度矩阵。

CMOS图像传感器动态范围扩展技术

CMOS有源像素图像传感器动态范围的扩展可采用各种技术,如对数像素结构、横向溢出栅像素结构、多次曝光技术、局部曝光技术等,其中多次曝光技术在可获得大动态范围图像的同时,信噪比(SNR)较高。