超声应变力成像对诊断甲状腺良性结节纤维化的应用价值

目的 探讨超声应变力成像对诊断甲状腺良性结节纤维化的应用价值。方法 选取本中心经病理证实为良性的甲状腺结节 155个,术前均行超声弹性成像检查,依据病理结果将其分为伴纤维化组（n=125）、无纤维化组（n=30）,并对 2组间应变率比值进行对比分析。以病理结果为金标准,计算应变率比值在诊断甲状腺良性结节是否伴有纤维化的敏感度和特异度。结果 伴纤维化组应变率比值［3.14（1.143,7.050）］高于良性无纤维化组［1.41（1.020,2.345）］（P＜0.05）。经 ROC曲线分析,应变率比值＞2.62,提示甲状腺良性结节可能存在纤维化,此时应变率比值的曲线下面积为 0.664（0.548,0.780）,敏感度为 56.7%,特异度为 77.6%。结论 超声弹性成像应变率比值对诊断甲状腺良性结节纤维化有一定的应用价值。     

Acoustic excitations and elastic heterogeneities in disordered solids

In the recent years, much attention has been devoted to the inhomogeneous nature of the mechanical response at the nanoscale in disordered solids. Clearly, the elastic heterogeneities that have been characterized in this context are expected to strongly affect the nature of the sound waves which, in contrast to the case of perfect crystals, cannot be completely rationalized in terms of phonons. Building on previous work on a toy model showing an amorphization transition, we investigate the relationship between sound waves and elastic heterogeneities in a unified framework by continuously interpolating from the perfect crystal, through increasingly defective phases, to fully developed glasses. We provide strong evidence of a direct correlation between sound wave features and the extent of the heterogeneous mechanical response at the nanoscale.In crystals, molecules thermally oscillate around the periodic lattice sites and vibrational excitations are well understood in terms of quantized plane waves, the phonons (1). The vibrational density of states (vDOS) in the low-frequency regime is well described by the Debye model, where the vibrational modes are the acoustic phonons. In contrast, disordered solids, including structural glasses and disordered crystals, exhibit specific vibrational properties compared with the corresponding pure crystalline phases. It is not possible here to give a fair review of the extensive theoretical and experimental work generated by these issues; we therefore mention below a few facts that we consider the most relevant in the present context. The origin of the vDOS modes in excess over the Debye prediction around ω ∼1 THz, the so-called Boson peak (BP), is still debated (see, among many others, refs. 2 and 3). At the BP frequency, Ω^BP, localized modes have also been observed (4). Acoustic plane waves, which are exact normal modes in crystals, can still propagate in disordered solids. Indeed, at low frequencies, Ω, and long wavelengths, Λ, acoustic sound waves do not interact with disorder and can propagate conforming to the expected macroscopic limit. However, as Ω is increased beyond the Ioffe–Regel (IR) limit, Ω^IR, acoustic excitations interact with the disorder and are significantly scattered (5–7). Interestingly, this strong scattering regime occurs around the BP position, Ω^IR ∼ Ω^BP (8, 9). The exact origin of this phenomenon and its connection to the BP remain elusive.A possible rationalization of the above issues is based on the existence of elastic heterogeneities (10), which can originate from structural disorder, as in structural glasses (2), or disordered interparticle potentials, even in lattice structures such as disordered colloidal crystals (11). In the heterogeneous-elasticity theory of refs. 7 and 12 this amounts to consider spatial statistical fluctuations of the shear modulus. Within the framework of jamming approaches and using effective medium theories, elastic heterogeneities are related to the proximity of local elastic instabilities (13). Recent simulation work (14–16) has clearly demonstrated their existence in disordered solids. This is at variance with the case of simple crystals, which are characterized by a fully affine response and homogeneous moduli distributions (17). More specifically, in the large length scale limit, macroscopic moduli are observed. In contrast, as the length scale is reduced, moduli heterogeneities are detected, at a typical length scale ξ ≃ 10−15σ (15), where σ is the typical atomic diameter. Breakdown of both continuum mechanics (18) and Debye approximation (5, 6) has been demonstrated at the same mesoscopic length-scale ξ, where they are still valid for crystals. Remarkably, the wave frequency corresponding to the wavelength Λ ∼ ξ is very close to Ω^IR ∼ Ω^BP (19). Altogether these results indicate that a close connection must exist between elastic heterogeneities and acoustic excitations. In this paper we precisely address this point.In ref. 20 we considered a numerical model featuring an amorphization transition (21). We showed how to systematically deform the local moduli distributions, evaluated by coarse-graining the system in small domains of linear length scale w. We characterized the degree of elastic heterogeneity in terms of SD of those distributions and studied the effect on normal modes (eigenvalues of the Hessian matrix) and thermal conductivity. Building on that work, we are now in the position to investigate the relation between elastic heterogeneities and acoustic excitations, unifying in a single framework ordered and disordered solid states and considering quantities directly probed by experiments. By interpolating in a controlled way from perfect crystals, through increasingly defective phases, to fully developed amorphous structures, we (i) calculate the dynamical structure factors, extracting the relevant spectroscopic parameters; (ii) characterize the wave vector dependence of sound velocity and broadening of the acoustic excitations and clarify their nature in terms of the IR limit; and (iii) provide, for the first time to our knowledge, direct evidence of the correlation of the excitations lifetimes and Ω^IR with the magnitude of the elastic heterogeneities.     

Functional traits explain variation in plant life history strategies

Ecologists seek general explanations for the dramatic variation in species abundances in space and time. An increasingly popular solution is to predict species distributions, dynamics, and responses to environmental change based on easily measured anatomical and morphological traits. Trait-based approaches assume that simple functional traits influence fitness and life history evolution, but rigorous tests of this assumption are lacking, because they require quantitative information about the full lifecycles of many species representing different life histories. Here, we link a global traits database with empirical matrix population models for 222 species and report strong relationships between functional traits and plant life histories. Species with large seeds, long-lived leaves, or dense wood have slow life histories, with mean fitness (i.e., population growth rates) more strongly influenced by survival than by growth or fecundity, compared with fast life history species with small seeds, short-lived leaves, or soft wood. In contrast to measures of demographic contributions to fitness based on whole lifecycles, analyses focused on raw demographic rates may underestimate the strength of association between traits and mean fitness. Our results help establish the physiological basis for plant life history evolution and show the potential for trait-based approaches in population dynamics.Recent evidence for global patterns of functional variation in plants, such as the leaf economics spectrum (1, 2), the wood economics spectrum (3), and the seed size–seed number tradeoff (4, 5), has convinced many ecologists that functional traits offer the best available approach for achieving a general predictive understanding of communities and ecosystems (6, 7). Trait-based approaches are now being used to predict the outcome of community assembly (8–10), global vegetation dynamics (11), and the rate of ecosystem processes (6, 12–14). A central assumption of trait-based ecology is that morphological traits determine physiological performance, which influences vital rates and determines individual fitness and life history evolution (15, 16). However, because of the challenge of quantifying the contribution of traits to fitness, the assumed links between functional traits and life history have not been fully tested.Research in tropical and Mediterranean forests has revealed cross-species relationships between functional traits and the survival and growth rates of individuals (3, 17–24). Although these relationships provide evidence that functional traits influence vital rates, they offer only limited insight into associations between those traits and individual fitness and life history. Vital rates (e.g., survival and fecundity) represent fitness components, but their influence on mean fitness, defined as the population growth rate (λ), is best understood in the context of the full lifecycle of a species (25, 26). A significant negative correlation between wood density and individual growth (18) might not translate into a significant effect on mean fitness if individual growth has little influence on λ. Conversely, a weak relationship between a functional trait and another vital rate could have a significant effect on mean fitness if that vital rate has a strong influence on λ. Perturbation analyses, such as the sensitivities and elasticities frequently applied to matrix projection models (27), address this problem by quantifying the contribution of vital rates to λ (28), making it possible to characterize a species'' overall life history in terms of the relative importance of survival, individual growth, and fecundity to mean fitness. Species with slow life histories have population growth rates with high elasticities to survival, whereas species with fast life histories have relatively higher elasticities to individual growth or fecundity (29, 30).Armed with vital rate elasticities, we can test quantitative hypotheses about whether functional tradeoffs scale up to generate life history tradeoffs. For example, plants can allocate their reproductive effort to provision a few large seeds, which tolerate low light and resource availability and have a high survival probability, or they can spread their reproductive effort among many small seeds, maximizing fitness under high resource availability (31, 32). If this functional tradeoff at the seedling stage translates into a life history tradeoff, seed mass should be positively related to the elasticity of the population growth rate to survival and negatively related to elasticities to individual growth and fecundity. The leaf economics spectrum represents another allocation tradeoff. Species can construct long-lived, well-defended leaves that are often favored in low resource environments or build leaves that assimilate carbon quickly under conditions of high resource availability but are prone to rapid tissue loss (1, 33). Species with slow leaf economics traits, such as long leaf lifespans, low specific leaf area (SLA), and low leaf N, might also lead slow lives, characterized by high elasticities to survival and low elasticities to individual growth and recruitment. A wood economics spectrum also exists: species with dense wood tend to have higher survival but lower relative growth rates than species with soft wood (3, 34). Elasticities to survival should increase with wood density, whereas elasticities to individual growth and fecundity should decrease.The main obstacle in testing these hypotheses is availability of the detailed demographic data necessary to describe a species’ full lifecycle and estimate vital rate elasticities. We overcame this limitation by crossing the TRY Global Plant Traits Database (35) with the COMPADRE Plant Matrix Database (www.compadre-db.org/), a collection of published matrix population models. This approach produced a dataset of 222 plant species spanning a global range of biomes and perennial growth forms (Table S1), for which we have at least one functional trait measurement as well as a matrix population model that we used to calculate the elasticity of the population growth rate to each of the three vital rates: survival, growth, and fecundity (30).Our primary objective was to evaluate the ability of functional traits to explain variation across species in life history, which we quantified with vital rate elasticities. Our secondary objective was to evaluate whether inferences about life history can be drawn directly from the raw vital rates, which would save researchers the considerable time and effort required to parameterize population models and calculate elasticities. We used two statistical approaches to quantify relationships between vital rate elasticities and seed mass, wood density, and leaf economics traits (leaf lifespan, SLA, and leaf N). Dirichlet regression is a multivariate approach that accounts for the fact that the survival, growth, and fecundity elasticities for each species sum to one but does not account for phylogenetic relationships. Phylogenetic generalized least squares (PGLS) regression ignores the nonindependence of the elasticities but accounts for phylogenetic relationships. We repeated both types of regressions with plant growth form and then biome included as covariates to confirm that trait effects did not simply represent differences between trees and herbaceous species or plants adapted to different environments.     

聚焦解决干预模式对急性心肌梗死患者心理弹性水平及自护能力的影响

目的探究聚焦解决干预模式对急性心肌梗死患者心理弹性水平及自护能力的影响。方法选择2017年7月~2019年7月我科收治的急性心肌梗死患者64例,按随机数字表法分为对照组和观察组,各32例。对照组采取常规护理。观察组采取聚焦解决干预模式。比较两组心理弹性水平及自护能力。结果观察组心理弹性水平评分显著高于对照组(P<0.05,P<0.001);观察组自护能力评分显著高于对照组(P<0.05,P<0.001)。结论聚焦解决干预模式在急性心肌梗死患者中的应用,能提升心理弹性水平,增强其自护能力。     

初诊原发性肝癌手术患者心理弹性影响因素分析

目的探讨初诊原发性肝癌手术患者心理弹性的影响因素。方法随机抽样选取我院2017年10月至2018年10月80例初诊原发性肝癌手术患者为研究对象,收集患者基本信息,采用心理弹性量表以及医学应对方式问卷评价患者的心理弹性水平和应对方式。结果初诊原发性肝癌手术患者心理弹性影响单因素分析中学历、职业、家庭人均月收入、疾病知识了解程度、应对方式比较差异具有统计学意义(P<0.05);多元线性回归分析显示,职业、家庭收入、学历、面对和屈服应对方式可预测心理弹性水平,差异有统计学意义(P<0.05)。结论初诊原发性肝癌手术患者心理弹性水平受多种因素影响,医护人员应关注患者心理变化,采取积极有效措施,提高患者的心理弹性水平及生存质量。     

From the Cover: The macroscopic delamination of thin films from elastic substrates

The wrinkling and delamination of stiff thin films adhered to a polymer substrate have important applications in “flexible electronics.” The resulting periodic structures, when used for circuitry, have remarkable mechanical properties because stretching or twisting of the substrate is mostly accommodated through bending of the film, which minimizes fatigue or fracture. To date, applications in this context have used substrate patterning to create an anisotropic substrate-film adhesion energy, thereby producing a controlled array of delamination “blisters.” However, even in the absence of such patterning, blisters appear spontaneously, with a characteristic size. Here, we perform well-controlled experiments at macroscopic scales to study what sets the dimensions of these blisters in terms of the material properties and explain our results by using a combination of scaling and analytical methods. Besides pointing to a method for determining the interfacial toughness, our analysis suggests a number of design guidelines for the thin films used in flexible electronic applications. Crucially, we show that, to avoid the possibility that delamination may cause fatigue damage, the thin film thickness must be greater than a critical value, which we determine.     

The differences in characteristics between health-care users and non-users: implication for introducing community-based health insurance in Burkina Faso

The purposes of this study are to describe the characteristics of different health-care users, to explain such characteristics using a health demand model and to estimate the price-related probability change for different types of health care in order to provide policy guidance for the introduction of community-based health insurance (CBI) in Burkina Faso. Data were collected from a household survey using a two stage cluster sampling approach. Household interviews were carried out during April and May 2003. In the interviewed 7,939 individuals in 988 households, there were 558 people reported one or more illness episodes; two-thirds of these people did not seek professional care. Health care non-users display lower household income and expenditure, older age and lower perceived severity of disease. The main reason for choosing no-care and self-care was ‘not enough money’. Multinomial logistic regression confirms these observations. Higher household cash-income, higher perceived severity of disease and acute disease significantly increased the probability of using western care. Older age and higher price-cash income ratio significantly increased the probability of no-care or self-care. If CBI were introduced the probability of using western care would increase by 4.33% and the probability of using self-care would reduce by 3.98%. The price-related probability change of using western care for lower income people is higher than for higher income although the quantity changed is relatively small. In conclusion, the introduction of CBI might increase the use of medical services, especially for the poor. Co-payment for the rich might be necessary. Premium adjusted for income or subsidies for the poor can be considered in order to absorb a greater number of poor households into CBI and further improve equity in terms of enrolment. However, the role of CBI in Burkina Faso is rather limited: it might only increase utilisation of western health care by a probability of 4%.     

心脉通1号对冠心病患者周围动脉弹性及相关因素的影响

目的探讨自拟心脉通1号对冠心病患者周围动脉弹性及相关因素的影响。方法将确诊冠心病患者70例随机分为2组,2组均予常规治疗,治疗组加服心脉通1号,疗程12个月,观察2组治疗前后大小动脉弹性指数、血压、中医证候积分、心绞痛发作及用药情况、高敏C反应蛋白(hs-CRP)水平及生化指标变化。结果2组患者治疗后大小动脉弹性指数均有显著降低,中医证候积分及hs-CRP有明显下降,以治疗组更为明显。2组患者治疗后血脂、血糖均明显降低,2组间无显著性差异。治疗前后2组患者肝肾功能及血压未见明显变化。结论心脉通1号对冠心病患者的动脉弹性、炎症因子及中医证候积分有较为明显的改善作用。