Human perception of horizontal trunk and head rotation in space during vestibular and neck stimulation

Summary The vestibular signal of head motion in space must be complemented by a neck signal of the trunk-to-head excursion in order to provide the individual with information on trunk motion in space. This consideration led us to study psychophysically the role of vestibular-neck interaction for human self-motion perception. Subjects (Ss) were presented with passive horizontal rotations of their trunk and/or head (sinusoidal rotations, f=0.025 –0.4 Hz) in the dark for vestibular and neck stimulation, as well as for combinations of both. Ss' perception was evaluated in terms of gain (veridical perception of stimulus magnitude, G=1), phase, and detection threshold. (1) Perception of trunk rotation in space. During vestibular stimulation (whole-body rotation) and neck stimulation (trunk rotation with the head kept stationary) the frequency-transfer characteristics underlying this perception were very similar. The gain fell short; it was only about 0.7 at 0.4 and 0.2 Hz stimulus frequency and was further attenuated with decreasing frequency. In contrast, the phase was close to that of actual trunk position. The gain attenuation was found to be a function of the peak angular velocity of the stimulus, a fact, which we related to a velocity threshold of the order of 1 deg/s. During the various vestibular-neck combinations used, Ss' perception was again erroneous, reflecting essentially the sum of its two non-ideal constituents. However, there was one noticeable exception; during the combination head rotation on stationary trunk, Ss veridically perceived their trunk as stationary (compatible with the notion that the sum yielded zero). (2) Perception of head rotation in space. During vestibular stimulation, Ss' estimates showed the same non-ideal gain-vs.-frequency characteristics as described above for the trunk. Neck stimulation induced an illusion as if the head had been rotated in space. This neck contribution was such that, when it was combined with its vestibular counterpart during head rotation on stationary trunk, the perception became almost veridical. On closer inspection, however, this neck contribution was found to reflect the sum of two components; one was the non-ideal neck signal contributing to the perception of trunk in space, the other was an almost ideal neck signal of head-on-trunk rotation. (3) The results could be described by a simple model. In this model, the erroneous vestibular signal head in space is primarily used to create an internal representation of trunk in space. To this end, it is combined with the closely matching neck signal of trunk to head. The perception of head rotation in space is achieved by summing this trunk in space signal with the almost ideal head on trunk signal, again of nuchal origin. These seeming complex interactions have two implications: (i) the head is referred to trunk coordinates, whereas the trunk is referred to space coordinates; (ii) there is at least one condition in the dark where orientation is correct (despite an erroneous vestibular signal), i.e., during head rotation on stationary trunk.Supported by Deutsche Forschungsgemeinschaft, SFB 325     

Eye movement disorders after frontal eye field lesions in humans

Eye movements were recorded electro-oculographically in three patients with a small ischemic lesion affecting the left frontal eye field (FEF) and in 12 control subjects. Reflexive visually guided saccades (gap and overlap tasks), antisaccades, predictive saccades, memory-guided saccades, smooth pursuit and optokinetic nystagmus (OKN) were studied in the three patients. Staircase saccades and double step saccades were also studied in one of the three patients. For both leftward and rightward saccades, latency in the overlap task (but not in the gap task) and that of correct antisaccades and of memory-guided saccades was significantly increased, compared with the results of controls. There was a significant decrease in the amplitude gain of all rightward saccades programmed using retinotopic coordinates (gap and overlap tasks, predictive and memory-guided saccades), whereas the amplitude gain of corresponding leftward saccades was preserved. Such an asymmetry between leftward and rightward saccades was significant. In the staircase paradigm as well as for the first saccade in the double step paradigm (with the use of retinotopic coordinates in both cases), the amplitude gain of rightward saccades was also significantly lower than that of leftward saccades. Moreover, in the double step paradigm, the amplitude gain of the first rightward saccade was significantly lower than that of the second rightward saccade (programmed using extraretinal signals), which was preserved. The percentage of errors in the antisaccade task did not differ significantly from that of normal subjects. In the predictive saccade paradigm, the percentage of predictive rightward saccades was significantly decreased. The left smooth pursuit gain for all tested velocities, the right smooth pursuit gain for higher velocities, and the left OKN gain were significantly decreased. The results show, for the first time in humans, that the FEF plays an important role in (1) the disengagement from central fixation, (2) the control of contralateral saccades programmed using retinotopic coordinates, (3) saccade prediction and (4) the control of smooth pursuit and OKN, mainly ipsilaterally. In contrast, the left FEF did not appear to be crucial for the control of the only type of saccades programmed using extraretinal signals studied here.     

Fractal system — A time domain approach

A method to analyze the fractal system in the time domain is presented so that the dynamic behavior of the system can be studied. The fractal system is represented by a set of linear time-varying differential equations whose order depends on the order of the system under non-fractal condition. Four different types of fractal system are considered and their solutions in the time domain are presented. These analyses show that the fractal system is dynamically more stable with smooth changes of magnitude and less oscillatory than the non-fractal system. Examples of the physiological system of the conduction pathways in the heart and also the polarization phenomena of noble metal are presented to illustrate the phonomena.     

PRUFILE: a clinical and laboratory database for the genetics centre

The growing complexity and volume of workload in a Clinical Genetics Centre can rapidly swamp the available clerical facilities. The multiuser database described gives facilities not only for administrative control and documentation but also for the production of data for clinical and scientific analysis. The close link between clinical and laboratory databases gives great versatility and easy expansion as new tests and disciplines are applied to clinical genetic problems.     

Biological balance of sodium and potassium

Summary The rhythm of renal sodium and potassium excretion was measured in 4-h-intervals in 12 subjects. Each person exhibited clear circadian variations of each variable with a maximum between 8 a.m. and 4 p.m. In each subject and for both circadian rhythms the oscillation mean was correlated to the range of oscillation (amplitude).Increase in sodium or potassium excretion during 1 day resulted in an increase of oscillation range. The oscillation means of sodium and potassium periodicity did not correlate.The properties of biological control systems with oscillating correcting variables are comparable to those of technical control systems. The significance of circadian rhythm for the control of electrolyte balance is indicated.     

Assessing Diet Quality of Indigenous Food Systems in Three Geographically Distinct Solomon Islands Sites (Melanesia,Pacific Islands)

Indigenous Solomon Islanders, like many living in Pacific Small Island Developing States (PSIDS), are currently experiencing the global syndemic—the combined threat of obesity, undernutrition, and climate change. This mixed-method study aimed to assess nutrition transitions and diet quality by comparing three geographically unique rural and urban indigenous Solomon Islands populations. Participants in rural areas sourced more energy from wild and cultivated foods; consumed a wider diversity of foods; were more likely to meet WHO recommendations of >400 g of non-starchy fruits and vegetables daily; were more physically active; and had significantly lower body fat, waist circumference, and body mass index (BMI) when compared to urban populations. Urban populations were found to have a reduced ability to self-cultivate agri-food products or collect wild foods, and therefore consumed more ultra-processed foods (classified as NOVA 4) and takeout foods, and overall had less diverse diets compared to rural populations. Clear opportunities to leverage traditional knowledge and improve the cultivation and consumption of underutilized species can assist in building more sustainable and resilient food systems while ensuring that indigenous knowledge and cultural preferences are respected.     

Effects of Coronavirus Disease Pandemic on Tuberculosis Notifications,Malawi

The coronavirus disease (COVID-19) pandemic might affect tuberculosis (TB) diagnosis and patient care. We analyzed a citywide electronic TB register in Blantyre, Malawi and interviewed TB officers. Malawi did not have an official COVID-19 lockdown but closed schools and borders on March 23, 2020. In an interrupted time series analysis, we noted an immediate 35.9% reduction in TB notifications in April 2020; notifications recovered to near prepandemic numbers by December 2020. However, 333 fewer cumulative TB notifications were received than anticipated. Women and girls were affected more (30.7% fewer cases) than men and boys (20.9% fewer cases). Fear of COVID-19 infection, temporary facility closures, inadequate personal protective equipment, and COVID-19 stigma because of similar symptoms to TB were mentioned as reasons for fewer people being diagnosed with TB. Public health measures could benefit control of both TB and COVID-19, but only if TB diagnostic services remain accessible and are considered safe to attend.     

How can an agent-based model explore the impact of interventions on children's physical activity in an urban environment?

Insufficient physical activity (PA) among most children and adolescents is a global problem that is undermining the realisation of numerous developmental and health benefits. The aim of this study was to explore the potential impact of interventions on PA by using an agent-based model (ABM) simulating children's daily activities in an urban environment. Three domains for interventions were explored: outdoor play, school physical education and active travel. Simulated interventions increased children's average daily moderate-to-vigorous PA by 2–13 min and reduced the percentage of children not meeting PA guidelines, from 34% to 10%–29%, depending on the intervention. Promotion of active travel and outdoor play benefited more those in a higher socio-economic position. Agents' interactions suggested that: encouraging activity in diverse groups will reduce percentage of the least active in the population; and initiating outdoor events in neighbourhoods can generate an enhancing effect on children's engagement in PA. The ABM provided measurable outcomes for interventions that are difficult to estimate using reductionist methods. We suggest that ABMs should be used more commonly to explore the complexity of the social-environmental PA system.     

超声弹性成像联合BI-RADS分类在乳腺微小癌诊断中的临床价值

目的:探讨在乳腺微小癌诊断中联合应用超声弹性成像及数据系统(BI-RADS)分类的临床价值。方法:选择2018年3月~2019年3月本院接收的疑似乳腺微小癌的96例患者作为研究对象。均进行超声弹性成像检查、BI-RADS分类,以病理检查结果为诊断金标准,比较单项检查与联合检查的准确率、灵敏度、特异度。结果:数据显示,在96例疑似乳腺微小癌患者中,共80例患者经病理检查确诊为乳腺微小癌,同时乳腺钼靶联合超声检查的准确性、灵敏度均高于单项检测,数据之间的差异有统计学意义(P<0.05)。此外,单项与联合检测的特异度对比,差异无统计学意义(P>0.05)。结论:在乳腺微小癌诊断中联合应用超声弹性成像及BI-RADS分类检查,可有效提高诊断准确性及灵敏度,对早期疾病诊断、临床治疗具有重要意义。