Cosmogenic nuclei

Cosmogenic nuclei, nuclides formed by nuclear interactions of galactic and solar cosmic rays with extraterrestrial or terrestrial matter are discussed. Long lived radioactive cosmogenic isotopes are focused upon. Their uses in dating, as tracers of the interactions of cosmic rays with matter, and in obtaining information on the variation of primary cosmic ray flux in the past are discussed

New modeling of the Vostok ice flow line and implication for the glaciological chronology of the Vostok ice core

International audienceWe have used new spaceborne (elevation) and airborne (ice thickness) data to constrain a 2D1/2 model of snow accumulation and ice flow along the Ridge B‐Vostok station ice flow line (East Antarctica). We show that new evaluations of the ice flow line geometry (from the surface elevation), ice thickness (from low‐frequency radar data), and basal melting and sliding change significantly the chronology of the Vostok ice core. This new Vostok dating model reconciles orbital and glaciological timescales and is in good agreement with the Dome Fuji glaciological timescale. At the same time, the new model shows significantly older ages than the previous GT4 timescale for the last glacial part, being thus in better agreement with the GRIP and GISP2 chronologies

Measurements in atmospheric electricity in a vertical plane

It was found by early workers in atmospheric electricity that, during conditions of steady rain, when the potential gradient at the ground was negative the potential gradient at the top of a high mast was occasionally positive. This indicated the presence of negative space charge in the layer between the two measurements. To farther investigate this effect simultaneous recordings were taken of the potential gradient and the precipitation current at the top and bottom of the mast, 21 metres high, situated in a field adjacent to Durham Observatory. Large differences in the values of the precipitation currents at the two levels were found. Due to the concentration of the lines of force on the earthed mast, and so on the upper shielded collector, laboratory experiments were carried out to investigate the charging effects caused when drops splash in a region of high potential gradient. It was found that the differences between the currents could be accounted for by the splashing of drops on the edges of the upper collector. As there is no obvious way of correcting for this effect it would appear that the shielded rain collector of the design used in the present work is unsuitable for measuring the precipitation current in regions of high potential gradient and even in other regions, the recorded currents must be considered with caution. Also drops were found to release negative charge to the air in regions of aero potential gradient. The actual reversal of sign of potential gradient between the top and bottom of the mast was only observed tor a number of very short periods, the longest being 4½ minutes, during low potential gradients. But on the majority of recordings the potential gradients did indicate the presence of excess of negative space charge in the layer below the top of the meat, although on occasions the space charge was positive. The space charge was of the same sign, and varied in the same sense, as the potential gradient recorded at the ground. Considering these points an attempt is made to explain the reversal effect in terms of layers of space charge between the cloud and the ground. The layer being due to the charge on the rain, the charge released when drops splash, and a separation or electrode effect due to the potential gradient of the cloud

Meteoritic ablation and fusion spherules in Antarctic ice

In the course of two Antarctic expeditions in 1980/1981 and 1982/1983 approximately 4 metric tons of documented ice samples were collected from the Atka Bay Ice Shelf, Antarctica, and subsequently shipped for cosmic dust studies. After filtration of the melt water, approximately 700 Antarctic spherules (AAS) in the size range of 5 to 500 microns were handpicked from the filter residue under optical microscopes. For the chemical investigation of single dust grains the following techniques were applied: scanning electron microscopy (SEM), X-ray analysis (EDAX), instrumental neutron activation analysis (INAA), laser microprobe mass analysis (LAMMA), and accelerator mass spectroscopy (AMS). For more than 95% of the total mass the bulk and trace elements were determined in single grain analyses using EDAX, INAA, and LAMMA. The element pattern of the dust particles was compared with that of typical terrestrial material and meteoritic matter. The majority of the spherules exhibited elemental compositions compatible with meteoritic element patterns

Clinical Reasoning to Advance Medication Safety by Senior Nursing Students

Nursing students in their final year of their nursing education program are expected to administer medications to patients safely and competently. Currently, there is a lack of research with regard to how senior nursing students are using clinical reasoning to support medication safety in the clinical setting. This qualitative descriptive case study explored how senior nursing students applied critical thinking and clinical reasoning to support medication safety in their final clinical practicums. The study took place in 2019 and consisted of 13 face-to-face interviews with senior nursing students in their final clinical rotation. Six themes emerged from the interviews. Students described (1) administering medications safely by recognizing and clustering cues, (2) administering medications safely to the right patient in the context of care, (3) administering medications safely by determining the correct action, (4) administering medications safely to patients for the right reason, (5) reflecting on clinical reasoning experiences that supported medication safety, and (6) unit culture impact clinical reasoning about medication safety. Nursing students described how they used their clinical reasoning to support safe medication management and administration in clinical settings. Based on the findings from this study, we recommend that nursing education programs enhance opportunities for students to develop and reflect on their clinical reasoning about safe medication administration in clinical settings. Résumé Il est attendu que les étudiantes en sciences infirmières qui terminent leur formation soient en mesure d’administrer des médicaments de façon sécuritaire et compétente. Les recherches sur la façon dont les étudiantes finissantes en sciences infirmières utilisent le raisonnement clinique pour soutenir la sécurité pharmacologique en milieu clinique sont actuellement insuffisantes. Cette étude de cas descriptive et qualitative a exploré la manière dont ces étudiantes exerçaient la pensée critique et le raisonnement clinique pour assurer la sécurité pharmacologique au cours de leur dernier stage clinique. L’étude a été effectuée en 2019 et comprenait 13 entretiens individuels avec des étudiantes en sciences infirmières de 4e année lors de leur dernier stage en milieu clinique. Six thèmes sont ressortis de l’analyse de ces entretiens. Les étudiantes ont décrit administrer des médicaments de manière sécuritaire (1) en reconnaissant et en regroupant les indices, (2) en les administrant au bon patient dans le contexte des soins, (3) en déterminant la bonne action, (4) en les administrant aux patients pour la bonne raison,(5) en réfléchissant sur les expériences de raisonnement clinique qui ont soutenu la sécurité pharmacologique et (6) la culture de l’unité a eu un impact sur le raisonnement clinique concernant la sécurité pharmacologique. Les étudiantes en sciences infirmières ont expliqué comment elles ont utilisé leur raisonnement clinique pour favoriser la gestion et l’administration sécuritaires de médicaments dans les milieux cliniques. Compte tenu des résultats de cette étude, nous recommandons que les programmes de formation en sciences infirmières fournissent davantage d’occasions permettant aux étudiantes de développer et de réfléchir à leur raisonnement clinique en matière d’administration sécuritaire des médicaments dans les milieux de soins

26Al measurement with a cyclotron

We have used the accelerator facility ALICE to count directly small quantities (∼ 5 × 109 atoms) of the isotope 26Al (half-life = 7.3 x 105 years). We discuss how measurement of this nuclide in marine sediments, in conjunction with similar measurements of 10 Be (half-life = 1.5 × 106 years), can be used as an absolute dating technique. The method used here to avoid interference from the isobar 26Mg is applicable to a number of other isobars of interesting long lived nuclides, thus expanding the potential application of the accelerator technique

Motor Behavior Literature Fails to Translate: A Preliminary Investigation into Coaching and Focus of Attention in Recreational Distance Runners.

International Journal of Exercise Science 13(5): 789-801, 2020. The benefits of using an external focus relative to an internal focus for endurance activities are well documented. However, literature has revealed that internally focused instructions are predominantly adopted in the field, and existing data are limited to highly-skilled level populations. Moreover, athletes’ focus of attention during fatigue invoking activities is unknown. The purpose of the current study was to examine what type of feedback and instructions experienced recreational individuals receive and their self-adopted focus of attention when fatigued. Distance runners answered a questionnaire related to instruction and feedback from coaches and thoughts that the athletes experienced while fatigued. The results showed that more than half of the instructions runners received from coaches were internally focused and consisted of both knowledge of performance and knowledge of results. Self-reported focus of runners when fatigued revealed that only 15% of task-related thoughts were externally focused. Despite a large body of motor behavior literature, attentional strategies shown to increase performance and learning were not predominantly present (from coaches or self-adopted) for this population of experienced recreational distance runners

Attention, workload, and performance: A dual-task simulated shooting study

During skill execution, performers have been shown to attend to different aspects of movement, the external effects of one’s action, or to other environmental information. A variety of psychological mechanisms have been proposed to account for the differential outcomes when adopting each attentional strategy. However, there is limited information about the extent to which different attentional foci change the workload demands of task performance. To examine this, the current study administered the NASA-Task Load Index following a simulated shooting dual-task. Participants performed the primary shooting task alone (control), and also with a secondary task that directed attention toward an aspect of skill execution (skill-focused) and an unrelated environmental stimulus (extraneous focus). Primary and secondary task performances were significantly greater in the extraneous focus compared to the skill-focused dual-task. Also, workload was significantly lower during the extraneous focus compared to the skill-focused dual-task condition. Further analyses revealed that workload significantly mediated the effects of skill level on performance during the skill-focused and extraneous focus dual-tasks and various subscales of workload (i.e., temporal demand) contributed unique amounts of variance to this relationship. A discussion of the relationship between attention, workload and its subcomponents, skill level, and performance is presented