Characteristics and utility of combined duplex color-coded ultrasonography in the cervical rotational position with head MRI and MRA in the differential diagnosis of apogeotropic direction-changing positional nystagmus

Objective:To determine whether cervical ultrasonography,magnetic resonance imaging(MRI),and magnetic resonance angiography(MRA)are useful in the differential diagnosis of etiology and understanding the pathophysiology in cases of apogeotropic direction-changing positional nystagmus(DCPN).Methods:Thirty patients with apogeotropic DCPN were classified into 11 cases of central disease,seven cases of mixed central and peripheral disease,and 12 cases of peripheral disease by differential diagnosis based on various balance function,neuro-otological,and imaging tests.Cervical ultrasonography using the cervical rotation method and MRI and MRA of the head and neck were performed in most patients with apogeotropic DCPN.We reviewed the presence of abnormal imaging findings according to the disease etiology.Results:Of the 30 patients with apogeotropic DCPN,23 showed vascular abnormalities or central lesions on imaging.Vascular lesions were found in six of the 12 patients with peripheral disease.Cervical ultrasonography with cervical rotation detected blood flow disturbance in the vertebral artery in eight patients in whom the disturbance could not be detected by MRI or MRA of the head and neck.Discussion:We hypothesize that the causative disease of apogeotropic DCPN may be strongly associated with circulatory insufficiency of the vertebrobasilar and carotid arteries,and that impaired blood flow in these vessels may affect peripheral vestibular and central function.In patients with apogeotropic DCPN,examinations of vestibular function,central nervous system symptoms,and brain hemodynamics are valuable for differential diagnosis.

Rays’ Change of Directions between Inertial Frames and Stellar Aberration

The path of a light’s signal is one and the same in the universal space regardless of the inertial frame by which it is identified. However, only one frame can be taken stationary and identified with the universal space while all other frames are moving. The direction of the path of a light’s pulse in a moving frame is determined in terms of its direction in the stationary one;the result is utilized to explain stellar aberration and show that the tilted direction in the moving frame depends only on its velocity. The aberration increment vector is introduced and employed to determine the apparent position of a star at each point of the earth orbit. Aberration in an earth satellite relative to the geocentric frame is presented. The direction’s change of a light beam between graded inertial frames promotes explaining aberration in an earth’s satellite in parallel to stellar aberration on earth.

Revisiting the response of western North Pacific tropical cyclone intensity change to vertical wind shear in different directions

The effect of vertical wind shear(VWS)directions on the change in western North Pacific tropical cyclone(TC)intensity is revisited in this study.Results show that the differences in the correlations between VWS in different orientations and the change in TC nondimensional intensity highly diminish,although slight differences are still present.The subtle differences in the correlations are likely associated with different synoptic-scale patterns at upper and lower levels.This result suggests that,in addition to thermodynamic effects,dynamic roles of the synoptic-scale patterns associated with the VWS should also be taken into account when the authors examine how VWS in different directions affects TC intensity change.

INDEX OF DIRECTION CHANGE OF ZONALLY AVERAGED WIND AND CHANGE OF SEASON

In this paper, a Wind Direction Change Index (WI), which can describe four-dimensional spatiotemporal changes of the atmospheric circulation objectively and quantitatively, is defined to study its evolution and seasonal variation. The first four modes can be obtained by EOF expansion of the zonally averaged WI. The first mode reveals the basic spatial distribution of the annually averaged WI. The second mode reflects the quasi-harmonic parts of the WI deviations. Tropical, subtropical and extratropical monsoon areas can be clearly reflected by this mode. The third mode reflects the non-harmonic parts of the WI deviations. It shows the so-called February reverse in stratospheric atmosphere as well as the asymmetric seasonal changes from spring to fall and from fall to spring due to both the land-sea distribution contrast between the Northern and Southern Hemispheres and the nonlinear effect of atmospheric and ocean fluids. The fourth mode reveals the northward advancing of the global reversed wind fields from spring to summer and their southward withdrawal from summer to autumn.

Active control of surface plasmon polaritons with phase change materials

Active control of surface plasmon polaritons(SPPs)is highly desired for nanophotonics.Here we employ a phase change material Ge_(2)Sb_(2)Te_(5)(GST)to actively manipulate the propagating direction of SPPs at the telecom wavelength.By utilizing the phase transition-induced refractive index change of GST,coupled with interference effects,a nanoantenna pair containing GST is designed to realize switchable one-way launching of SPPs.Devices based on the nanoantenna pairs are proposed to manipulate SPPs,including the direction tuning of SPP beams,switchable SPP focusing,and switchable cosine–Gauss SPP beam generating.Our design can be employed in compact optical circuits and photonics integration.

Effect of abruptly changing withdrawal rate on solidification microstructure in directionally solidified Al-4.5wt%Cu alloy

Al-4.5wt.%Cu alloy has been directionally solidified at constant and abruptly changing withdrawal rates, respectively. The effects of the withdrawal rate on solidification microstructure, primary dendrite arm spacing(PDAS) and liquid solute distribution in front of the solid-liquid interface were investigated. The experimental results for the PDAS at a constant withdrawal rate agree well with the values calculated by the Hunt, Trivedi and Hunt-Lu models. At an abrupt change in the withdrawal rate, the maximum to minimum ratio of the PDAS at a given solidification parameter, i.e. λ1max/λ1min, is more than 2, and the PDAS values are remarkably history-dependent. Further, the liquid-solute distribution curve based on theoretical calculation shows that the larger the initial withdrawal rate is, the smaller the minimum of liquid solute concentration in front of the solid-liquid interface is after the abrupt change in withdrawal rate.

Direct Digital Frequency Control Based on the Phase Step Change Characteristic between Signals

We present a new digital phase lock technology to achieve the frequency control and transformation through high precision multi-cycle group synchronization between signals without the frequency transformation circuit. In the case of digital sampling, the passing zero point of the phase of the controlled signal has the phase step characteristic, the phase step of the passing zero point is monotonic continuous with high resolution in the phase lock process, and using the border effect of digital fuzzy area, the gate can synchronize with the two signals, the quantization error is reduced. This technique is quite different from the existing methods of frequency transformation and frequency synthesis, the phase change characteristic between the periodic signals with different nominal is used. The phase change has the periodic phenomenon, and it has the high resolution step value. With the application of the physical law, the noise is reduced because of simplifying frequency transformation circuits, and the phase is locked with high precision. The regular phase change between frequency signals is only used for frequency measurement, and the change has evident randomness, but this randomness is greatly reduced in frequency control, and the certainty of the process result is clear. The experiment shows that the short term frequency stability can reach 10-12/s orders of magnitude.

Research on Passive Locating Method Using Phase Rate of Change with Variant Posture of the Observer

Technology of passive location has broad prospects in applications. In this paper, the method using the phase rate of change for the single observer passive location is introduced based on existing methods. One can obtain the direction of the target with phase information of two orthogonal interferometers on the observer and the radial distance with the corresponding phase rate of change. Then the target can be located with high speed and precision. A locating approach is given when the flying posture of t...

HOUSE CHANGE DETECTION BASED ON DSM OF AERIAL IMAGE IN URBAN AREA

The change of house often brings on the change of DSM in an area over different periods. If we can apply information of the height of houses to reinforce the house change detection, the reliability and efficiency of detection methods will be improved greatly.From this viewpoint, a new approach taking advantage of both height data from an image pair and image data is proposed to detect the house change in urban area and is called 'data fusion technology'.

The Yearly Most Wind Direction Abnormality and Meteorological Disaster in Yumen in Recent 57 Years

By using the historical data during 1953-2009,the yearly most wind direction change in Yumen and the meteorological disasters of 4 times yearly most wind direction abnormality in recent 57 years were analyzed. The results showed that there were 51 years which the yearly most wind direction was the easterlies in Yumen,and the westerly had 4 years. There were 2 years which the occurrence frequencies of westerly and easterlies were same. 4 years which the yearly wind direction abnormality was the most were in 1961,1979,1987 and 1998. When the yearly wind direction abnormality was the most,the meteorological disaster was serious. The total output of grain in Gansu Province in 1961 was the least in the history in recent 60 years. The serious drought disaster in 1961 caused that half agricultural population in Gansu seriously lacked of the grain,and the dead population sharply increased. In the end of 1961,the population in Gansu decreased nearly million than in 1958. The annual precipitation in 1979 was the most in recent 57 years. The daily precipitation on June 11,1987 was the most in June of recent 57 years in Yumen. The annual average temperature in 1998 was the highest in Yumen in recent 57 years.

Change Detection Based on DSM and Image Features in Urban Areas

On the basis of stereo image analysis, the change detection of man-made objects in urban areas is introduced. Information of the height of man-made objects can be applied to reinforce their change detection. By comparison between the new and old DSMs, the changed regions are extracted. However, our aim is to detect changes of man-made objects in urban area and further in the potential areas by the means of line-feature matching and gradient direction histogram. The experiments based on the aerial images from Japan have proven that the algorithm is correct and efficient.

Integrating cross-sensor high spatial resolution satellite images to detect subtle forest vegetation change in the Purple Mountains,a national scenic spot in Nanjing,China

Accurate information on the location and magnitude of vegetation change in scenic areas can guide the configuration of tourism facilities and the formulation of vegetation protection measures.High spatial resolution remote sensing images can be used to detect subtle vegetation changes.The major objective of this study was to map and quantify forest vegetation changes in a national scenic location,the Purple Mountains of Nanjing,China,using multi-temporal cross-sensor high spatial resolution satellite images to identify the main drivers of the vegetation changes and provide a reference for sustainable management.We used Quickbird images acquired in 2004,IKONOS images acquired in 2009,and WorldView2 images acquired in 2015.Four pixel-based direct change detection methods including the normalized difference vegetation index difference method,multi-index integrated change analysis(MIICA),principal component analysis,and spectral gradient difference analysis were compared in terms of their change detection performances.Subsequently,the best pixel-based detection method in conjunction with object-oriented image analysis was used to extract subtle forest vegetation changes.An accuracy assessment using the stratified random sampling points was conducted to evaluate the performance of the change detection results.The results showed that the MIICA method was the best pixel-based change detection method.And the object-oriented MIICA with an overall accuracy of 0.907 and a kappa coefficient of 0.846 was superior to the pixel-based MIICA.From 2004 to 2009,areas of vegetation gain mainly occurred around the periphery of the study area,while areas of vegetation loss were observed in the interior and along the boundary of the study area due to construction activities,which contributed to 79%of the total area of vegetation loss.During 2009–2015,the greening initiatives around the construction areas increased the forest vegetation coverage,accounting for 84%of the total area of vegetation gain.In spite of this,vegetation loss occurred in the interior of the Purple Mountains due to infrastructure development that caused conversion from vegetation to impervious areas.We recommend that:(1)a local multi-agency team inspect and assess law enforcement regarding natural resource utilization;and(2)strengthen environmental awareness education.

Distinguishing the Effects of Cryosphere Change in the Background of Climate Change in China

Climate change has major impacts directly on the natural ecosystem and human society, of which the cryosphere is most easily affected be-cause of its frangibility and sensitivity. Similarly, cryosphere change has numerous impacts on the natural ecosystem and human society, which may resemble an indirect influence of climate change. These two types of impacts, in shared fields, are distinguished in space and time by effective mechanisms and processes. Climate change has positive and negative impacts on some systems, which may be adjusted by cryosphere change. These indirect and direct impacts may be distinguished, and then correct policies and measures can be made against these changes.

Research on Frequency of the Aftershock Sequence of the Wenchuan Earthquake Based on Coseismic Coulomb Stress Change

By the aftershock frequency estimation method based on the calculation of coseismic static Coulomb stress changes and rate-and state-dependent fault constitutive law,we calculate the frequency of "direct "aftershocks of the Wenchuan earthquake related to coseismic static Coulomb stress changes in its aftershock zone and the areas nearby.It shows that the frequency is significantly lower than the truth in the main rupture zone,especially in the southern rupture zone,due to the decrease of stress level on the rupture plane of the main shock resulting from coseismic Coulomb stress change.The study also shows that the effect of the Coulomb stress change on the duration of aftershock activity is associated with the lower limit magnitude.The duration is about 15-16 months for aftershocks above ML4.0,and close to 60 months for aftershocks above ML3.5.In this period,the ratio of the"direct"aftershocks caused by coseismic Coulomb stress change ranges between 44.7% to48.6%,which suggests that,even in the "effective"period of coseismic Coulomb stress changes,about half of the aftershocks on the main shock rupture plane are independent of coseismic Coulomb stress changes.It is pointed out that those aftershocks may be related to the afterslip or the viscoelastic relaxation,which are time dependent cases.

Toward a sustainable future:Examining the interconnectedness among Foreign Direct Investment(FDI),urbanization,trade openness,economic growth,and energy usage in Australia

The energy demand in Australia is increasing with the industrialization and rapid economic growth.This study analyzed the relationships among the economic growth,Foreign Direct Investment(FDI),trade openness,urbanization,and energy usage in Australia based on the data from World Development Indicators(WDI)from 1972 to 2021.The results indicates that there is a cointegration among economic growth,FDI,trade openness,urbanization,and energy usage,which was traced through the autoregressivedistributed lag(ARDL).The Zivot-Andrews unit root test reveals that energy usage,economic growth,FDI,urbanization,and trade openness show significant structural breaks in 1993,1996,1982,2008,and 1994,respectively.The ARDL model shows that economic growth has a positive and significant effect on energy usage in the long-run(0.814)and short-run(0.809).Moreover,the results also show that FDI(0.028)and trade openness(0.043)have positive impacts on energy usage in the long-run.However,urbanization shows a negative and significant influence on energy usage in the long-run(–0.965).Then,the research demonstrates a unidirectional causation between energy usage and trade openness,with energy usage significantly causing trade openness.The current study endorses energy consumption policies and investment strategies for a paradigm shifting from a reliance on fossil fuels as the primary energy source to renewable energy sources.These findings have profound implications for sustainable energy usage.

动态风向变化下风力机叶片和塔架应力及功率特性分析

风向变化显著影响风力机气动载荷分布,从而影响风力机稳定高效的运行,而气动载荷是风力机结构应力和功率变化主要影响因素之一。该文以S翼型三叶片水平轴风力机为研究对象,在旋转平台上进行风洞实验,对不同风向变化速度(0.5°、1°、1.5°、2°/s)下风力机叶片和塔架的应力以及风力机功率特性进行分析。结果表明:风向变化速度为0.5°/s时,在风向由0°变化到30°时,叶片弦向和展向应力值和风力机功率下降幅度最大;在风向由0°变化到20°时,叶片应力值和功率下降较为缓慢,风向变化结束后,风力机应力与功率会进一步减小;风向变化角度在0°~20°范围内,受叶片转速和气动载荷下降速度与风向变化耦合作用的影响,塔架应力值出现较大波动,并随风向变化速度的增加,波动出现的区间从15°~20°提前到0°~5°;风向变化结束后,叶片转速持续下降,造成塔架应力仍有不同程度的波动。结果可为考虑风向变化下运行的风力机结构设计提供一定理论依据。

基于MEMS陀螺的高温随钻定向测斜仪研究

针对油气井测量时所面临的小孔径、超深井、温度范围广、温度变化率高、工作时间长等挑战,研究了基于MEMS陀螺仪的定向测斜仪,设计了MEMS陀螺定向测斜仪软硬件系统.为确保该环境下的测量精度提出了一种动态温度补偿方案,并采用基于小波滤波多尺度分析的方法对动态温变环境下陀螺输出信号进行去噪滤波处理,以实现定向测斜仪系统的测量精度.论文给出了定向测斜仪硬件系统方案、定向测斜算法、小波多尺度滤波算法.测试结果表明:该系统在常温和动态温变环境下井斜方位角精度优于±2°,井斜角精度优于±0.1°,工作温度最高150℃,可适应我国深层油气井勘探开发的应用场景需求.

风向变化下不同材料叶片动态应力试验研究

为了了解不同材料风力机叶片在风向变化过程中的应力变化规律,以木质、玻璃纤维和碳纤维材料的S型风力机叶片为研究对象,使用风洞及动态旋转平台模拟风向变化情况并通过试验方法进行研究.结果表明:在同风速、同尖速比条件下,弹性模量较大的碳纤维叶片叶根前缘处应力值远大于玻璃纤维叶片和木质叶片叶根前缘处应力值,重量较大的玻璃纤维叶片比碳纤维叶片和木质叶片叶根前缘处应变值大;不同材料叶片叶根及展向应力、应变分布有所不同,但总体基本呈现由前缘(0.25C)向后缘(0.90C)、由叶根(0.20R)向叶尖(0.90R)减小的趋势;风向变化开始后,刚度高的碳纤维叶片由于抵抗弹性变形的能力强,其各测点应力、应变值最先出现明显下降趋势,之后依次为玻璃纤维叶片和木质叶片,3种材料叶片各测点的应力、应变值均呈现反S型下降曲线;叶片材料不同会导致同翼型同一测点处受到拉伸或挤压作用的大小、最大主应力方位角出现较大差异.

闽东方言变韵的机制与方向

从闽东方言的闽清县坂东镇新近出现的变韵现象出发,通过声学分析发现,变韵在不同声调条件下有不同的时长结构。闽东南北两片代表性方言(福州、连江、宁德、周宁)松紧复合韵母的声学分析显示,声调对元音时长的影响在先,继而元音时长的改变诱发其响度增减。因此,也可以说,声调影响元音时长,元音时长与相对响度相关,三者共同构成闽东方言变韵的机制。最后,结合闽东方言韵母的共时特点和历史演变,可以将变韵的基本规律归纳为首成分扩张与尾成分扩张两大类型,各韵母依声调环境而沿不同的方向演变。

煤厚变化区围岩能量积聚规律及开采方向对其影响

为揭示煤厚变化区围岩能量积聚规律以及开采方向对其影响,以鹤岗峻德煤矿17~#煤层冲击倾向性煤层为研究背景,以组合岩层为对象,探讨了煤厚变化区应力转移机制,揭示了煤厚变化区原岩应力与煤岩厚度比、弹性模量比之间关系,阐明了开采方向对煤厚变化区采动应力及能量积聚规律的影响。结果表明:由于岩石和煤的强度(刚度)差异,导致煤厚变化区域主应力分布不均匀,在煤厚变薄区域出现峰值应力,变厚区域出现谷值应力,且煤厚变化范围越大、煤岩弹性模量比越小,峰值应力越大,谷值应力越小;受采动应力影响,在煤厚变化区域超前支承压力与煤厚变化异常应力叠加,围岩应力集中程度高;由薄向厚回采,工作面前方超前支承压力区和应力异常区叠加,存在1个冲击危险区,由厚向薄回采存在2个冲击危险区,从而由薄向厚回采更为合理。针对煤厚变化区采动应力及能量积聚规律,提出调控采场围岩结构、围岩应力、增加冲击阻能的防控思路,并进行工程应用,效果良好。