An Investigation into the Bromate Method of Manganese Determination

Throughout the history of research in the science of Chemistry the problem of the quantitative determination of manganese has always been a perplexing one. The results have usually fallen short of the theoretical value and has necessitated the application of an empirical factor(1) which is always undesirable to the true research scientist, if not to the commercial analyst

The “broken escalator” phenomenon: Vestibular dizziness interferes with locomotor adaptation

BACKGROUND: Although vestibular lesions degrade postural control we do not know the relative contributions of the magnitude of the vestibular loss and subjective vestibular symptoms to locomotor adaptation. OBJECTIVE: To study how dizzy symptoms interfere with adaptive locomotor learning. METHODS: We examined patients with contrasting peripheral vestibular deficits, vestibular neuritis in the chronic stable phase (n = 20) and strongly symptomatic unilateral Meniere’s disease (n = 15), compared to age-matched healthy controls (n = 15). We measured locomotor adaptive learning using the “broken escalator” aftereffect, simulated on a motorised moving sled. RESULTS: Patients with Meniere’s disease had an enhanced “broken escalator” postural aftereffect. More generally, the size of the locomotor aftereffect was related to how symptomatic patients were across both groups. Contrastingly, the degree of peripheral vestibular loss was not correlated with symptom load or locomotor aftereffect size. During the MOVING trials, both patient groups had larger levels of instability (trunk sway) and reduced adaptation than normal controls. CONCLUSION: Dizziness symptoms influence locomotor adaptation and its subsequent expression through motor aftereffects. Given that the unsteadiness experienced during the “broken escalator” paradigm is internally driven, the enhanced aftereffect found represents a new type of self-generated postural challenge for vestibular/unsteady patients

Subcortical control of precision grip after human spinal cord injury.

The motor cortex and the corticospinal system contribute to the control of a precision grip between the thumb and index finger. The involvement of subcortical pathways during human precision grip remains unclear. Using noninvasive cortical and cervicomedullary stimulation, we examined motor evoked potentials (MEPs) and the activity in intracortical and subcortical pathways targeting an intrinsic hand muscle when grasping a small (6 mm) cylinder between the thumb and index finger and during index finger abduction in uninjured humans and in patients with subcortical damage due to incomplete cervical spinal cord injury (SCI). We demonstrate that cortical and cervicomedullary MEP size was reduced during precision grip compared with index finger abduction in uninjured humans, but was unchanged in SCI patients. Regardless of whether cortical and cervicomedullary stimulation was used, suppression of the MEP was only evident 1-3 ms after its onset. Long-term (∼5 years) use of the GABAb receptor agonist baclofen by SCI patients reduced MEP size during precision grip to similar levels as uninjured humans. Index finger sensory function correlated with MEP size during precision grip in SCI patients. Intracortical inhibition decreased during precision grip and spinal motoneuron excitability remained unchanged in all groups. Our results demonstrate that the control of precision grip in humans involves premotoneuronal subcortical mechanisms, likely disynaptic or polysynaptic spinal pathways that are lacking after SCI and restored by long-term use of baclofen. We propose that spinal GABAb-ergic interneuronal circuits, which are sensitive to baclofen, are part of the subcortical premotoneuronal network shaping corticospinal output during human precision grip

A Causal Role for Primary Motor Cortex in Perception of Observed Actions.

It has been proposed that motor system activity during action observation may be modulated by the kinematics of observed actions. One purpose of this activity during action observation may be to predict the visual consequence of another person’s action based on their movement kinematics. Here, we tested the hypothesis that the primary motor cortex (M1) may have a causal role in inferring information that is present in the kinematics of observed actions. Healthy participants completed an action perception task before and after applying continuous theta burst stimulation (cTBS) over left M1. A neurophysiological marker was used to quantify the extent of M1 disruption following cTBS and stratify our sample a priori to provide an internal control. We found that a disruption to M1 caused a reduction in an individual’s sensitivity to interpret the kinematics of observed actions; the magnitude of suppression of motor excitability predicted this change in sensitivity

Impairment of spatial cognitive function with preservation of verbal performance during spatial disorientation

Spatial disorientation, which is responsible for up to 30% of aircraft accidents causes impairment of cognitive function which may further compromise a pilot's ability to think his way out of the situation and regain control [1,]. The functional-anatomical separation of spatial and verbal processing [10,11] raises the possibility of selective interference between the task of resolving spatial disorientation and the ability to perform concurrent spatial, as opposed to verbal, secondary tasks. We report for the first time a degradation of spatial task performance with preservation of verbal performance when subjects in a simulator are disoriented by conflict between self- motion and visual flow in the view of the external environment

Grasp-specific motor resonance is influenced by the visibility of the observed actor

Motor resonance is the modulation of M1 corticospinal excitability induced by observation of others' actions. Recent brain imaging studies have revealed that viewing videos of grasping actions led to a differential activation of the ventral premotor cortex depending on whether the entire person is viewed versus only their disembodied hand. Here we used transcranial magnetic stimulation (TMS) to examine motor evoked potentials (MEPs) in the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) during observation of videos or static images in which a whole person or merely the hand was seen reaching and grasping a peanut (precision grip) or an apple (whole hand grasp). Participants were presented with six visual conditions in which visual stimuli (video vs static image), view (whole person vs hand) and grasp (precision grip vs whole hand grasp) were varied in a 2 × 2 × 2 factorial design. Observing videos, but not static images, of a hand grasping different objects resulted in a grasp-specific interaction, such that FDI and ADM MEPs were differentially modulated depending on the type of grasp being observed (precision grip vs whole hand grasp). This interaction was present when observing the hand acting, but not when observing the whole person acting. Additional experiments revealed that these results were unlikely to be due to the relative size of the hand being observed. Our results suggest that observation of videos rather than static images is critical for motor resonance. Importantly, observing the whole person performing the action abolished the grasp-specific effect, which could be due to a variety of PMv inputs converging on M1

Realistic depiction of symptoms and consequences of parental problem drinking in young adult novels

This research was a content analysis study of young adult novels that contained a parent with a drinking problem. The researcher wanted to determine the level of real ism regarding the characterizations of the child of an alcoholic, the drinker, and the spouse of the drinker. The hypothese predicted that a majority of the books would include: 1. three or more consequence of drinking on the child, 2. four or more consequences or symptoms on the drinker, and 3. one or more consequences suffered by the spouse. A checklist that listed known consequences and symptoms of alcohol abuse was developed. A four member panel recommended books to the researcher. Fifteen books were randomly selected to be analyzed. All of the hypotheses were accepted. It was determined that there •is a high level of real ism in young adult fiction portraying alcoholic parents that were published between 1979 and 1989

Preliminary space mission design under uncertainty

This paper proposes a way to model uncertainties and to introduce them explicitly in the design process of a preliminary space mission. Traditionally, a system margin approach is used in order to take the min to account. In this paper, Evidence Theory is proposed to crystallise the inherent uncertainties. The design process is then formulated as an optimisation under uncertainties(OUU). Three techniques are proposed to solve the OUU problem: (a) an evolutionary multi-objective approach, (b) a step technique consisting of maximising the belief for different levels of performance, and (c) a clustering method that firstly identifies feasible regions.The three methods are applied to the Bepi Colombo mission and their effectiveness at solving the OUU problem are compared