The glacial geomorphology of western Dronning Maud Land, Antarctica

Reconstructing the response of present-day ice sheets to past global climate change is important for constraining and refining the numerical models which forecast future contributions of these ice sheets to sea-level change. Mapping landforms is an essential step in reconstructing glacial histories. Here we present a new map of glacial landforms and deposits on nunataks in western Dronning Maud Land, Antarctica. Nunataks are mountains or ridges that currently protrude through the ice sheet and may provide evidence that they have been wholly or partly covered by ice, thus indicating a formerly more extensive (thicker) ice sheet. The map was produced through a combination of mapping from Worldview satellite imagery and ground validation. The sub-metre spatial resolution of the satellite imagery enabled mapping with unprecedented detail. Ten landform categories have been mapped, and the landform distributions provide evidence constraining spatial patterns of a previously thicker ice sheet

Ice surface changes during recent glacial cycles along the Jutulstraumen and Penck Trough ice streams in western Dronning Maud Land, East Antarctica

Reconstructing past ice-sheet surface changes is key to testing and improving ice-sheet models. Data constraining the past behaviour of the East Antarctic Ice Sheet are sparse, limiting our understanding of its response to past, present and future climate change. Here, we report the first cosmogenic multi-nuclide (10Be, 26Al, 36Cl) data from bedrock and erratics on nunataks along the Jutulstraumen and Penck Trough ice streams in western Dronning Maud Land, East Antarctica. Spanning elevations between 741 and 2394 m above sea level, the samples have apparent exposure ages between 2 ka and 5 Ma. The highest-elevation bedrock sample indicates (near-) continuous minimum exposure since the Pliocene, with a low apparent erosion rate of 0.15 ± 0.03 m Ma−1, which is similar to results from eastern Dronning Maud Land. In contrast to studies in eastern Dronning Maud Land, however, our data show clear indications of a thicker-than-present ice sheet within the last glacial cycle, with a thinning of ∼35–120 m during the Holocene (∼2–11 ka). Difficulties in separating suitable amounts of quartz from the often quartz-poor rock-types in the area, and cosmogenic nuclides inherited from exposure prior to the last deglaciation, prevented robust thinning estimates from elevational profiles. Nevertheless, the results clearly demonstrate ice-surface fluctuations of several hundred meters between the current grounding line and the edge of the polar plateau for the last glacial cycle, a constraint that should be considered in future ice-sheet model simulations

A Quantitative Study of the Mechanisms behind Thymic Atrophy in Gαi2-Deficient Mice during Colitis Development

Mice deficient for the G protein subunit Gαi2 spontaneously develop colitis, a chronic inflammatory disease associated with dysregulated T cell responses. We and others have previously demonstrated a thymic involution in these mice and an aberrant thymocyte dynamics. The Gαi2−/− mice have a dramatically reduced fraction of double positive thymocytes and an increased fraction of single positive (SP) thymocytes. In this study, we quantify a number of critical parameters in order to narrow down the underlying mechanisms that cause the dynamical changes of the thymocyte development in the Gαi2−/− mice. Our data suggest that the increased fraction of SP thymocytes results only from a decreased number of DP thymocytes, since the number of SP thymocytes in the Gαi2−/− mice is comparable to the control littermates. By measuring the frequency of T cell receptor excision circles (TRECs) in the thymocytes, we demonstrate that the number of cell divisions the Gαi2−/− SP thymocytes undergo is comparable to SP thymocytes from control littermates. In addition, our data show that the mature SP CD4+ and CD8+ thymocytes divide to the same extent before they egress from the thymus. By estimating the number of peripheral TREC+ T lymphocytes and their death rate, we could calculate the daily egression of thymocytes. Gαi2−/− mice with no/mild and moderate colitis were found to have a slower export rate in comparison to the control littermates. The quantitative measurements in this study suggest a number of dynamical changes in the thymocyte development during the progression of colitis

Tactile massage and hypnosis as a health promotion for nurses in emergency care-a qualitative study

<p>Abstract</p> <p>Background</p> <p>This study explores nursing personnel's experiences and perceptions of receiving tactile massage and hypnosis during a personnel health promotion project. Nursing in a short term emergency ward environment can be emotionally and physically exhausting due to the stressful work environment and the high dependency patient care. A health promotion project integrating tactile massage and hypnosis with conventional physical activities was therefore introduced for nursing personnel working in this setting at a large university hospital in Sweden.</p> <p>Methods</p> <p>Four semi-structured focus group discussions were conducted with volunteer nursing personnel participants after the health promotion project had been completed. There were 16 participants in the focus groups and there were 57 in the health promotion intervention. The discussions were transcribed verbatim and analysed with qualitative content analysis.</p> <p>Results</p> <p>The findings indicated that tactile massage and hypnosis may contribute to reduced levels of stress and pain and increase work ability for some nursing personnel. The sense of well-being obtained in relation to health promotion intervention with tactile massage and hypnosis seemed to have positive implications for both work and leisure. Self-awareness, contentment and self-control may be contributing factors related to engaging in tactile massage and hypnosis that might help nursing personnel understand their patients and colleagues and helped them deal with difficult situations that occurred during their working hours.</p> <p>Conclusion</p> <p>The findings indicate that the integration of tactile massage and hypnosis in personnel health promotion may be valuable stress management options in addition to conventional physical activities.</p

Physiological responses to low-force work and psychosocial stress in women with chronic trapezius myalgia

<p>Abstract</p> <p>Background</p> <p>Repetitive and stressful work tasks have been linked to the development of pain in the trapezius muscle, although the underlying mechanisms still remain unclear. In earlier studies, it has been hypothesized that chronic muscle pain conditions are associated with imbalance in the autonomic nervous system, predominantly expressed as an increased sympathetic activity. This study investigates whether women with chronic trapezius myalgia show higher muscle activity and increased sympathetic tone at baseline and during repetitive low-force work and psychosocial stress, compared with pain-free controls.</p> <p>Methods</p> <p>Eighteen women with chronic trapezius myalgia (MYA) and 30 healthy female controls (CON) were studied during baseline rest, 100 min of repetitive low-force work, 20 min of psychosocial stress (Trier Social Stress Test, TSST), and 80 min recovery. The subjects rated their pain intensity, stress and energy level every 20 min throughout the experiment. Muscle activity was measured by surface electromyography in the trapezius muscle (EMGtrap) and deltoid muscle (EMGdelt). Autonomic reactivity was measured through heart rate (HR), skin conductance (SCL), blood pressure (MAP) and respiration rate (Resp).</p> <p>Results</p> <p>At baseline, EMGtrap, stress ratings, and HR were higher in MYA than in CON. Energy ratings, EMGdelt, SCL, MAP and Resp were, however, similar in the two groups. Significant main group effects were found for pain intensity, stress ratings and EMGtrap. Deltoid muscle activity and autonomic responses were almost identical in MYA and CON during work, stress and recovery. In MYA only, pain intensity and stress ratings increased towards the end of the repetitive work.</p> <p>Conclusion</p> <p>We found increased muscle activity during uninstructed rest in the painful muscle of a group of women with trapezius myalgia. The present study could not confirm the hypothesis that chronic trapezius myalgia is associated with increased sympathetic activity. The suggestion of autonomic imbalance in patients with chronic local or regional musculoskeletal pain needs to be further investigated.</p

Effect of Stacking Sequence on Micro-Cracking in a Cryogenically Cycled Carbon/Bismaleimide Composite

An apparatus was developed to thermally cycle coupon-sized mechanical test specimens to −196 °C. Using this device, IM7/5250-4 carbon/bismaleimide cross-ply ([0/90]2S and [90/0/90/0/90/0/90/0/90]) and quasi-isotropic ([0/45/−45/90]S) laminates were submerged in liquid nitrogen (LN2) and returned to room temperature 400 times. Ply-by-ply micro-crack density (transverse cracks), micro-crack span, laminate modulus, and laminate strength were measured as a function of thermal cycles. The composite micro-cracked extensively in the surface plies followed by sparse micro-cracking of the inner plies. The tensile strength of the two blocked lay-ups (lay-ups with adjacent plies of the same orientation) decreased by 8.5% after 400 cycles. Sectioning of the samples revealed that the micro-cracks in the surface plies spanned the full width of the sample while many of the micro-cracks observed on the edge of the inner plies did not extend to the center of the samples, implying that a rectangular specimen with exposed free edges may result in a significantly different micro-crack density than a sample without free edges

Infrared predissociation spectra of water dimer in a supersonic molecular-beam

The infrared absorption spectrum of the hydrogen-bonded water dimer, (H2O)2, formed in a supersonic expansion, was recorded in the region of t