Modelling the Physical Human-Exoskeleton Interface

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Effect of Anions on the Iron Release Pathways of Human Serum Transferrin

Transferrin, the serum iron transport protein in humans, is used to transport 30-40 mg of iron per day through blood. The accessibility of transferrin makes it an attractive target for iron cheating therapeutic agents used in the treatment of iron overload. There is an ongoing search for ligands which can accelerate the rate of iron release, as the currently approved drug DFO has a very slow rate for iron removal. Previous studies have shown that anions can accelerate the rate of iron release. Studies on the effect of anions on the rates of iron release from C-terminal monoferric transferrin at pH 7.4 have been conducted using the ligands acetohydroxamic acid (AHA) and 1,2-dimethyl-3-hydroxy-pyridinone (L1), which follow saturation kinetics, and the ligands, nitrilotriacetic acid (NTA) and diethylenetriaminepentaacetic acid (DTPA), which follow first order kinetics with respect to the ligand concentration. The effects of sulfonates, phosphonates and phosphonocarboxylates have been studied. The anions are divided into two types, simple (non-coordinating) and complex (capable of chelating iron). The simple anions accelerate the rate of iron release, presumably by binding to an allosteric anion binding site on the transferrin. This binding increase the value of kmax for the saturation pathway for AHA and L1 and introduces a kmax for NTA, which otherwise does not have a saturation component. This changes the kinetic behavior of NTA from a strictly first-order dependence on the ligand concentration to complex kinetics, a combination of saturation and first-order kinetics. The complex anions, which can also chelate iron, decrease the rate of iron release by the reference ligands. These anions can also generate a small first order component for iron removal by ligands that normally follow saturation kinetics. These studies emphasize that the appearance of the first order component is due to the replacement of synergistic anion by the incoming chelating ligand and is not an allosteric effect of the anionic ligand. Distinct effects of anions on the saturation and first-order components for iron release are reported. For NTA, the major impact of anions is a decrease in the value of k’

Adsorption of PEO/PPO triblock co-polymers and wetting of coal

The adsorption characteristics of PEO/PPO/PEO triblock co-polymers on coal were investigated using surface tension and contact angle measurements. Although these surfactants have been widely used as wetting agents, it was observed that they increased the hydrophobicity of coal at concentrations below about 10-6 M. Surface tension studies were carried out to explain the reasons for this behavior. The surface tension versus concentration profiles displayed three distinct regions. In region I, surface tension decreased linearly and monomers were proposed to be the dominant species. This region extended to a surfactant concentration of about 10-6 M. In region II, a transition region between regions I and III, dimers, trimers, etc., were considered to form. In region III, micelles formed and surface tension was independent of concentration. The concentration at which monomers associate to form dimers, etc., is referred to as the critical association concentration (cac). The contact angle of coal increased when concentration was raised from low values to the cac. It decreased when the reagent concentration was above the cac. Finally, at concentrations above the cmc, the wetting of coal was complete and contact angle was zero

Subarachnoid haemorrhage mimicking unstable angina: a case report

Subarachnoid haemorrhage (SAH) is medical emergency caused by bleeding into the subarachnoid space. It is caused by rupture of an aneurysm or arteriovenous malformations (AVM). Symptoms of SAH are severe headache, nausea, vomiting, impaired consciousness and seizures. Neck stiffness and neck pain are relatively uncommon. Risk factors are high blood pressure, smoking, family history, alcoholism and even cocaine use. Diagnosis is mainly made by CT scan of head which should be done within six hours of the onset of symptoms and occasionally lumber puncture can also be done. An electrocardiogram (ECG) of all patients with subarachnoid should be done because patient with SAH can have myocardial ischemia due to increased level of circulating catecholamines or due to autonomic stimulation of the brain. ECG changes associated with SAH primarily reflect repolarisation abnormalities involving ST segment, T wave, U wave and QTc interval. Myocardial ischemia or infarction is often suspected in patients with SAH. Even troponin levels may be raised in these patients. However, suspicion of SAH is a contraindication for thrombolytic and anticoagulant therapy. This is a case of SAH which was initially treated for acute coronary syndrome (ACS) on the basis of symptoms and gradually changing ECG findings but on CT Head, patient was having SAH

An observational method for Postural Ergonomic Risk Assessment (PERA)

Monotonous, repetitive work characterizes production lines. Repetitive movements and awkward postures are the most prominent physical risk factors in the workplace. Various legislations have been enacted along with technical standards for ergonomic risk evaluation to ensure the safety of the operators. There are numerous methods to assess the ergonomic risk at work. However, most methods are not meant to be used for assessing cyclic work. This paper proposes a method, Postural Ergonomic Risk Assessment (PERA), which is suitable to evaluate the postural ergonomic risk of short cyclic assembly work. Its key features are simplicity and compliance with standards. The added value of the method is that it provides an analysis of every work task in the work cycle, which facilitates the identification of sources of high risk to the operator. The method has been verified on nine work cycles, constituted by 88 work tasks, and it demonstrates accordance with the European Assembly Worksheet (EAWS), which has been developed to comply with the relevant standards and is one of the most comprehensive tools for ergonomic risk assessment. Industrial relevance: The simplicity and the compliance with standards of the proposed method would allow for a quick check of every work task of the work cycle and identification of problem areas. With further work, it would be possible to integrate the method along with work design tools used in the industry

Modelling friction at the mechanical interface between the human and the exoskeleton

In virtual assessments of exoskeletons, often, friction is not modelled even though the actual interface consists of straps or moulded surfaces, where friction could play a significant role. In this work, the human-exoskeleton interaction during the use of a passive lower limb exoskeleton is modelled in three test cases through two different interface models. In particular, a model introducing friction at the human-exoskeleton interface is compared with a more conventional model that uses a kinematic joint to simulate the interface forces. Both the models show a good match between the empirical and predicted distribution of body weight between the subject and the exoskeleton. However, the results also show different trends of the moment required at the assisted joint by the different interface models, highlighting the importance of a realistic interface model to investigate the effectiveness of the exoskeleton in virtual assessments

Growth, development and yield of potatoes

Experiments were conducted in growth rooms to study the photoperiodic response of Pentland Crown. In field experiments the effects of sprouting techniques and the possibility of mixing of different physiologically aged tubers and the use of plant growth regulator, pp333 were studied. Sprout growth of the tubers used for planting was studied during storage. Light interception in the photo-synthetically active range (PAR), was measured in the crop canopies. Relevant literature relating to the present investigation was briefly reviewed. Tuberization in Pentland Crown was stimulated by relatively short days, lower temperature and higher irradiance. Pp333 allowed closer plant spacing (61 x 20cm) without any visible crowding effect, further it increased the allocation of assimilated to the tubers, which resulted in higher tuber yields and with a higher proportion of medium sized tubers. Sprout growth was linearly related to the initial tuber weight and day degrees above 4oC from dormancy break. Storing tubers in the cold before planting increased the sprout number and thus the proportion of main stems in the field. Time to reach 50% emergence was not reduced with increases in physiological age over 80 day degrees above 4oC. Cold (tubers stored at 3+/- 1oC until a day before planting) delayed tuber initiation but once the tuber had been initiated then the effect of physiological age disappeared and further tuber or overall plant growth or development was no more affected by the physiological age of the seed tuber. Yields from mixing different physiologically aged tubers were not different from those expected. The major factor affecting the growth of the crop was the water supply. The overall photosynthetic conversion efficiency of the canopy (g dry weight MJ-1 was intercepted) was 3.42g in 1980 in absence of any apparent water stress while in 1979 it was only 2.24g due to winter stress

Assessment of whole-head magnetoencephalography during transcranial electric entrainment of brain oscillations

Application of non-invasive brain stimulation for perturbing brain activity is well established. Various forms of brain stimulation protocols have been effectively demonstrated to modulate behavior associated with the perturbed brain activity. However, the interaction of brain stimulation with ongoing brain activity has been challenging to characterize as the stimulation artifacts in the recordings of brain activity impedes such characterization. The proposed amplitude modulated transcranial alternating current stimulation (tACSAM) attenuates possible stimulation artifacts at the frequency of interest. This is possible by modulating the amplitude of high frequency transcranial alternating current (tACS) signal at a lower physiological frequency of interest to generate the tACSAM signal. Furthermore, application of tACSAM allows localization of the perturbed brain activity with millimeter precision by applying spatial filters on magnetoencephalography (MEG) recordings. For characterization of the tACSAM-perturbed brain activity, conventional spectral analysis may not be sufficient. Thus, power and PLV were compared between tACS and tACSAM in a phantom model and MEG data recorded from healthy human volunteers. The synchronization estimate, phase lock value (PLV), is a measure of circular variance between two signals calculated as a function of instantaneous phase difference between the ongoing brain activity and the applied stimulation signal. Even though, systematic linear phase shifts due to the applied tES signal occur in MEG sensors, mathematically such systematic linear phase shifts nullify while calculating PLV. Systematic evaluation of the MEG data acquired during tACSAM showed increased PLV compared to tACS indicating increased demodulation in such paradigm. Upon observing tACSAM-related increased demodulation, it was still unclear whether such perturbations of brain activity could modulate behavior. To address this question, twenty volunteers while engaging in a working memory paradigm received tACSAM or no stimulation. Working memory is associated with transient storage and processing of information. Increasing the difficulty of working memory paradigm increases the amplitude of brain activity in the theta band (4 – 8 Hz), while encoding the temporal order of the transient information in the phase of the theta activity. Thus, by targeting individual’s theta peak frequency using tACSAM, it was possible to modulate the accuracy in the working memory paradigm. The accuracy on a working memory parading of volunteers receiving tACSAM deteriorated compared to the participants who did not receive brain stimulation. Therefore, targeting brain activity in theta band using tACSAM interferes with execution of normal working memory processes, probably by interfering with the maintenance of temporal order of the transient information. Furthermore, tACSAM but not sham stimulation inhibited the increase in amplitude of theta activity during the n-back task, which is essential for working memory processes. Even though, it is possible to assess the brain activity recorded during tACSAM, presence of stimulation artifacts in the assessed brain activity cannot be excluded. However, it was possible to gather evidence that tACSAM is associated with demodulation. TACSAM-induced phase synchrony at the modulation frequency was larger compared to tACS even though the power during tACS is larger compared to tACSAM. This observation is in favor of possible functional interaction of tACSAM signal with neurons in the brain. However, currently it is not possible to distinguish between the contribution towards demodulation of tACSAM signal by non-linearities of the stimulation setup and functional interactions with neurons in the brain. In conclusion, tACSAM can alter cognitive function, such as working memory performance, possibly through entrainment. The results obtained from such investigations must be interpreted with great care, as the extent by which possible stimulation artifacts impact the MEG recordings is not entirely clear. Further investigations are necessary to develop quantitative assessment techniques for characterizing artifacts of the stimulation and eventually develop brain state dependent stimulation paradigms in real time as a research tool and therapeutic intervention

EVALUATION OF THE EFFECT OF ELEVATED CO2 ON BIOEFFICACY OF BUPROFEZIN INSECTICIDE AGAINST BROWN PLANT HOPPER, Nilaparvata lugens (STÅL)

The effect of elevated CO2 (570±25ppm) on the brown plant hopper (BPH) population, rice yield parameters, and efficacy of buprofezin (0.05%) in terms of spray volume was studied in an open top chamber (OTCs) during rainy season 2017 and 2018. The pest population was observed to be higher during 2017 compared to the rainy season of 2018. Under elevated CO2, rice plants had more vegetative tillers (18%) and reproductive tillers (22.1%), but there was a decrease in 1000-seed weight (11.2%), seed number per panicle (3.91%), and grain yield (18.8%) in comparison to ambient CO2 grown rice plants. The spray volumes of 700, 600, 500, and 400 l/ha each caused higher BPH mortality under ambient CO2 compared to elevated CO2. A spray volume of 500 l/ha did not prove as effective under elevated CO2 as under ambient CO2. Lower efficacy of spray volume of 500 l/ha under elevated CO2 could be ascribed to higher canopy size under elevated CO2 due to higher tillering. Increased crop canopy size under elevated CO2 may thus require higher spray volume to ensure proper coverage. Results of the study suggested a need to revise spray volume recommendations to facilitate effective management of BPH under climate change