甘肃省生境质量变化的图谱特征

生境质量是影响地区生态系统服务价值和保护地球生态系统中生物多样性的重要因素。以地处三大自然区交汇带的甘肃省为研究对象,在定量估算地区2000—2018年生境质量水平基础上,基于图谱变化分析理论和InVEST模型,探索地区生境质量时空分异格局及其图谱转移状态和变化强度。结果表明: 2000—2018年,甘肃省生境质量总体维持中等水平并略有提升,在空间上自北向南呈逐级递增的阶梯式变化特征,在数量上则高低并存;从图谱转移视角分析,甘肃省生境质量格局较为稳定,未发生状态转移的图谱单元占主导,而在发生了生境质量状态转移的图谱单元中,“较高较低”、“较高高”、“较高低”这6类状态间的互换转移最显著,空间分布也较为集聚; “北剧南和”是甘肃省生境质量变化强度的主要格局,自北向南依次为“强变区”、“复合区”、“温缓区”和“平和区”4类变化强度区。     

The effect of grazing on winter survival of midday gerbil (Meriones meridianus) of different genders

The objective of this study was to investigate the effects of grazing on midday gerbil (Meriones meridianus) population characteristics and survival of animals of different genders. The experiment used a randomized complete block design and was conducted in Alxa Left Banner, Inner Mongolia, China, in 2002 (The agricultural reclamation plots set up in 1994). From April 2006 to October 2010, midday gerbils were live‐trapped in 3 light grazing plots, 3 overgrazed plots, and 3 grazing exclusion plots. The quantity of vegetation was investigated in the two different grazing intensity areas and grazing exclusion area to determine the relationship between gerbils and plant food availability. The results suggested that there was higher gerbil density, individual body mass, and daily body mass growth rate in the grazing exclusion sites than the other sites across the whole year. Females had higher survival in grazing exclusion areas than in other treatments, but the males’ survival showed the opposite pattern. Our results indicated that grazing negatively influenced the midday gerbil population by reducing food availability. Grazing influenced the survival rates of male midday gerbils positively, but had negative effects on females. The reason for gendered differences in survival rates of midday gerbils requires further investigation.     

CBCT引导放疗摆位误差对中上段食管癌患者受照射剂量的影响

摘要 目的：探究锥形束CT（CBCT）引导放疗摆位误差对中上段食管癌患者受照射剂量的影响。方法：选取2017年5月～2019年5月于我院收治的60例中上段食管癌患者为研究对象,所有患者均行CBCT图像、计划CT图像采集。在患者放疗前进行CBCT扫描,将CBCT图像与计划CT图像匹配,得到左右（x轴）、头脚（y轴）、前后（z轴）三个方向的线性误差,分析出现的误差及误差的分布规律。利用模拟实际照射系统,进行模拟计划,得到实际照射靶区及正常组织受照射剂量,将其与治疗前计划比较,研究摆位误差对患者受照剂量的影响。结果：患者整体摆位误差为x轴（2.91±2.20）mm,y轴（3.89±2.17）mm,z轴（2.44±1.64）mm,x轴的MPTV为4.054 mm,y轴的MPTV为8.183 mm,z轴的MPTV为3.482 mm。模拟计划的CI、PTV的Dmin、Dmean、D95%均低于标准计划差异显著（P均＜0.05）,而模拟计划的HI低于标准计划（P＜0.05）。模拟计划的脊髓Dmax高于标准计划（P＜0.05）,而标准计划与模拟计划的双肺V20、Dmean,心脏V40差异比较无统计学意义（P均＞0.05）。结论：CBCT引导放疗摆位误差对中上段食管癌患者影响较小,提高PTV受照射剂量及治疗准确程度,对脊髓有保护效果。摆位误差对心、肺的剂量分布无明显影响。     

癔球症患者食管测压结果、心理特征分析及小剂量阿米替林的干预效果研究

摘要 目的：分析患者的食管测压结果、心理特征及小剂量阿米替林的干预效果。方法：选取2017年5月~2019年5月期间上海市静安区市北医院收治的癔球症患者137例（癔球症组）,另选取同期到上海市静安区市北医院体检的健康志愿者50例（非癔球症组）,比较两组食管测压结果、癔球症症状评分量表（GETS）评分、汉密尔顿抑郁量表-17（HAMD-17）评分、汉密尔顿焦虑量表-14（HAMA-14）评分。按随机数字表法将癔球症患者分为对照组（n=68）和研究组（n=69）,对照组给予常规治疗,研究组则在对照组的基础上联合小剂量阿米替林干预。比较对照组、研究组的临床疗效、不良反应。结果：癔球症组、非癔球症组患者食管上括约肌（UES）长度、UES残余压、食管下括约肌（LES）静息压、收缩前沿速度（CFV）、远端潜伏时间（DL）组间比较差异无统计学意义（P>0.05）;癔球症组患者UES静息压高于非癔球症组（P<0.05）。癔球症组患者GETS、HAMA-14、HAMD-17评分高于非癔球症组（P<0.05）。研究组治疗后的临床总有效率为84.06%（58/69）,高于对照组的66.18%（45/68）（P<0.05）。两组不良反应发生率比较差异无统计学意义（P>0.05）。结论：相对于非癔球症患者,癔球症患者具有较高的UES静息压,癔球症症状及较为严重的不良情绪,采用小剂量阿米替林对癔球症进行干预可提高治疗有效率,用药安全性较好。     

Sex-specific differences in the prevalence of sarcopenia among pre-frail community-dwelling older adults in Saudi Arabia

ObjectivesTo assess sex differences in the prevalence of sarcopenia among pre-frail community-dwelling older adults in Saudi Arabia.MethodsThis was a cross-sectional study conducted at a tertiary-level hospital in Riyadh, Saudi Arabia, in 2019. The study participants were pre-frail community-dwelling older adults, according to the Edmonton Frail Scale. The SARC-F questionnaire was used to diagnose sarcopenia. The Katz Activities of Daily Living (ADL) was used to rank the adequacy of performance in six functions: bathing, dressing, toileting, transferring, continence, and feeding, while the Lawton Instrumental Activities of Daily Living scale was used to assess the more complex ADL necessary for living in the community.ResultsIn total, 283 community-dwelling older adults were recruited for this study, with a mean (±SD) age of 70.77 (±6.26) years; 72.7% of the total were female participants. The majority (85.5%) of the patients reported that they needed home care assistance. The mean ADL score of the participants was high, indicating high function and independence (KATZ-ADL: M 4.60 SD 1.75; Lawton Brody: 60%). The overall prevalence of sarcopenia among the studied participants was 65.7%, which was significantly higher among females (71.9%) than among males (59.1%), with a P-value of 0.007. Among the demographic characteristics of the participants, there was a significant difference in the need for home care assistance in female sarcopenic and non-sarcopenic participants (74.1% vs. 25.9%, p = 0.017), but without demonstrable difference in males. Additionally, there was a significant difference (P < 0.05) in the prevalence of sarcopenia between male and female participants according to ADL scores. The strongest predictor for sarcopenia prevalence in males was an ADL score <2 according to the Katz index, with an odds ratio of 6.5, while the need for home care was the only significant predictor of sarcopenia among female participants (OR 3.25, CI: 1.14–9.25, p = 0.02).ConclusionOverall, almost two-thirds of the studied pre-frail community-dwelling older adult population were sarcopenic. The prevalence of sarcopenia was significantly higher among females than males. The strongest predictor of sarcopenia was an ADL score <2 based on the Katz index in males and the need for home care assistance in females.     

Radioprotection of eye lens using protective material in neuro cone-beam computed tomography: Estimation of dose reduction rate and image quality

PurposeIn cerebral angiography, for diagnosis and interventional neuroradiology, cone-beam computed tomography (CBCT) scan is frequently performed for evaluating brain parenchyma, cerebral hemorrhage, and cerebral infarction. However, the patient’s eye lens is more frequently exposed to excessive doses in these scans than in the previous angiography and interventional neuroradiology (INR) procedures. Hence, radioprotection for the lenses is needed. This study selects the most suitable eye lens protection material for CBCT from among nine materials by evaluating the dose reduction rate and image quality.MethodsTo determine the dose reduction rate, the lens doses were measured using an anthropomorphic head phantom and a real-time dosimeter. For image quality assessment, the artifact index was calculated based on the pixel value and image noise within various regions of interest in a water phantom.ResultsThe protective materials exhibited dose reduction; however, streak artifacts were observed near the materials. The dose reduction rate and the degree of the artifact varied significantly depending on the protective material. The dose reduction rates were 14.6%, 14.2%, and 26.0% when bismuth shield: normal (bismuth shield in the shape of an eye mask), bismuth shield: separate (two separate bismuth shields), and lead goggles were used, respectively. The “separate” bismuth shield was found to be effective in dose reduction without lowering the image quality.ConclusionWe found that bismuth shields and lead goggles are suitable protective devices for the optimal reduction of lens doses.     

On the eptihermal neutron energy limit for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT): Study and impact of new energy limits

Background and purpose: Accelerator-Based Boron Neutron Capture Therapy is a radiotherapy based on compact accelerator neutron sources requiring an epithermal neutron field for tumour irradiations. Neutrons of 10 keV are considered as the maximum optimised energy to treat deep-seated tumours. We investigated, by means of Monte Carlo simulations, the epithermal range from 10 eV to 10 keV in order to optimise the maximum epithermal neutron energy as a function of the tumour depth.Methods: A Snyder head phantom was simulated and mono-energetic neutrons with 4 different incident energies were used: 10 eV, 100 eV, 1 keV and 10 keV. ¹⁰B capture rates and absorbed dose composition on every tissue were calculated to describe and compare the effects of lowering the maximum epithermal energy. The Therapeutic Gain (TG) was estimated considering the whole brain volume.Results: For tumours seated at 4 cm depth, 10 eV, 100 eV and 1 keV neutrons provided respectively 54%, 36% and 18% increase on the TG compared to 10 keV neutrons. Neutrons with energies between 10 eV and 1 keV provided higher TG than 10 keV neutrons for tumours seated up to 6.4 cm depth inside the head. The size of the tumour does not change these results.Conclusions: Using lower epithermal energy neutrons for AB-BNCT tumour irradiation could improve treatment efficacy, delivering more therapeutic dose while reducing the dose in healthy tissues. This could lead to new Beam Shape Assembly designs in order to optimise the BNCT irradiation.     

Eye lens and thyroid gland radiation exposure for patients undergoing brain computed tomography examination

This study aims to estimate the effective radiation dose and organ dose from head CT procedures. It was conducted in three main private hospitals in Khartoum State-Sudan, using Toshiba machines with 64 slices. The total number of patients included in this study was 142 patients (82 males and 60 females). The effective dose and organ dose were calculated by CT Expo software. The effective dose slightly varied among patients according to gender and age. The effective dose for female patients (5.99 mSv) was higher than that for male patients (5.84 mSv), and the pediatric dose (5.46 mSv) was lower than the adults’ dose (5.94 mSv).The dose for eye lens was found lower for male patients (89.117 mSv) than the dose for female patients (94.62) mSv). According to patients’ age: the dose received by the lens of the eye was much lower in pediatric (79.93 mSv) than the adults (92.41 mSv). The dose for thyroid in female patients (33.52 mSv) was higher than the male patients (28 mSv). The pediatric dose (28.34 mSv) was lower than the adults’ dose (30.64 mSv).Departmental imaging protocol and lack of training among hospital staff are expected to be responsible for these variations. Therefore, this study recommends that the CT technologists be trained on suitable strategies to achieve dose optimization. Moreover, patients’ doses must be monitored regularly.     

New head models extracted from thermal infrared (IR) images for dosimetry computations

In electromagnetic dosimetry, anatomical human models are commonly obtained by segmentation of magnetic resonance imaging or computed tomography scans. In this paper, a human head model extracted from thermal infrared images is examined in terms of its applicability to specific absorption rate (SAR) calculations. Since thermal scans are two-dimensional (2D) representation of surface temperature, this allows researchers to overcome the extensive computational demand associated with 3D simulation. The numerical calculations are performed using the finite-difference time-domain method with mesh sizes of 2 mm at 900 MHz plane wave irradiation. The power density of the incident plane wave is assumed to be 10 W/m². Computations were compared with a realistic anatomical head model. The results show that although there were marked differences in the local SAR distribution in the various tissues in the two models, the 1 g peak SAR values are approximately similar in the two models.