Glacial Geology of Muir Inlet, Southeast Alaska

The University Archives has determined that this item is of continuing value to OSU's history.Muir Inlet is in the northeast part of Glacier Bay National Monument in Southeastern Alaska, about 135 kilometers northeast of Juneau. Muir Inlet is part of a large dendritic glacial valley system that has three tidal glaciers. It is flanked on the east, north and west by peaks of the St. Elias Mountains, with maximum elevations of about 2,200 meters. To the south, Muir Inlet is joined by Wachusett and Adams Inlets before it joins Glacier Bay. The region has a maritime climate with cool summers and mild winters. Glaciers in this part of Glacier Bay Monument are downwasting and retreating rapidly, and vegetation is reestablishing itself on the deglaciated areas. The stratigraphy in Muir Inlet can be divided into six units. From oldest to youngest they are: (1) The Forest Creek Formation, which is marine clay, silt and sand with abundant marine fossils. Radiocarbon dating of shell material indicates a minimum age of 10,000 ± 220 years B.P. (2) The Muir Till is the lower, more weathered and indurated of two tills in the section. Wood at the interface between the Forest Creek Formation and Muir Till is 10,400 ± 260 years old. This gives a maximum age for Late Wisconsin ice advance in Muir Inlet. (3) The Van Horn Formation is composed of three members: a lower gravel, a middle lacustrine member, and an upper gravel. The Van Horn Formation was deposited during the interval from Late Wisconsin ice retreat to the beginning of the Neoglacial advance. Interstadial time lasted about 5,000 years, as determined by the dates of trees in place in this formation. Lake sediments accumulated from about 4,500 years B.P. to about 2,500 years B.P. Late interstadial gravels cover most lake deposits. (4) The Glacier Bay Till is the upper, relatively unweathered of the two tills in the section. Wood in place that is covered by this till has been used todate the Neoglacial ice advance in the Muir Inlet area. Ice moved westward down Wachusett Inlet and reached the base of the Curtis Hills 2,735 ± 160 years B.P., and ice had thickened and covered the lower two-thirds of White Thunder Ridge near the head of Muir Inlet, 2,120 ± 115 years B.P. Neoglacial ice may have started advancing as early as 3,000 years ago. Ice may have started retreating from a terminal moraine at Bartlett Cove in the late 1600's or early 1700's. By 1794, it was retreating north of Bartlett Cove. Since then, it has retreated at least 70 km to its present terminus in Muir Inlet. The recession from Icy Strait up Glacier Bay, about 100 km, is the greatest observed anywhere in the world. Trees are re-establishing themselves on the deglaciated terrain and the arms of Muir Inlet are once more filling with outwash. Uplift from ice unloading is known to be in the order of 3.5 cm/yr. Ice movement directions that can be plotted from ground observations (such as striae and crag-and-tail features) and from the study of aerial photographs, show that ice advanced down Muir Inlet from north to south. From old photographs, it has been determined that between 1890 and 1892 the McBride Remnant area was still covered by nearly 600 meters of ice. Ice continued to downwaste and retreat from 1892 to 1948. From 1948 to 1963, the rate of ice downwasting in the McBride Remnant region averaged 6.6 meters per year. Old photographs show a succession of old marginal drainage channels which can be traced across the McBride Remnant area. Smaller marginal drainage channels mark the former edges of dead ice that existed near the south end of the McBride Remnant region. Ice-cored kames and eskers are scattered throughout the McBride Remnant region. North of Nunatak Knob, crag-and-tail orientations suggest that, after separation from the Muir glacier, the McBride Remnant Glacier reversed its direction of flow. Streamlined glacial forms in the McBride Remnant area are composed of grooved till and gravel ridges and cragand-tail features. Drumlin-like forms occur near the mouth of Wachusett Inlet. Minor linear ridges crossing the McBride Remnant area were developed by filling of crevasses, till liberated from shear planes, and possible squeeze-ups into subglacial voids. A smaller network of closed or partly closed ice-disintegration ridges formed around the edges of detached, small ice blocks.National Science Foundation Grants GP-1058 and GP-2537, 1963-1964.The Ohio State University Research Foundation RF Projects 1639 and 1813

The effect of silica nanoparticle-modified surfaces on cell morphology, cytoskeletal organization and function

Chemical and morphological characteristics of a biomaterial surface are thought to play an important role in determining cellular differentiation and apoptosis. In this report, we investigate the effect of nanoparticle (NP) assemblies arranged on a flat substrate on cytoskeletal organization, proliferation and metabolic activity on two cell types, Bovine aortic endothelial cells (BAECs) and mouse calvarial preosteoblasts (MC3T3-E1). To vary roughness without altering chemistry, glass substrates were coated with monodispersed silica nanoparticles of 50, 100 and 300 nm in diameter. The impact of surface roughness at the nanoscale on cell morphology was studied by quantifying cell spreading, shape, cytoskeletal F-actin alignment, and recruitment of focal adhesion complexes (FAC) using image analysis. Metabolic activity was followed using a thiazolyl blue tetrazolium bromide assay. In the two cell types tested, surface roughness introduced by nanoparticles had cell type specific effects on cell morphology and metabolism. While BAEC on NP-modified substrates exhibited smaller cell areas and fewer focal adhesion complexes compared to BAEC grown on glass, MC3T3-E1 cells in contrast exhibited larger cell areas on NP-modified surfaces and an increased number of FACs, in comparison to unmodified glass. However, both cell types on 50 nm NP had the highest proliferation rates (comparable to glass control) whereas cells grown on 300 nm NP exhibited inhibited proliferation. Interestingly, for both cell types surface roughness promoted the formation of long, thick F-actin fibers, which aligned with the long axis of each cell. These findings are consistent with our earlier result that osteogenic differentiation of human mesenchymal progenitor cells is enhanced on NP-modified surfaces. Our finding that nanoroughness, as imparted by nanoparticle assemblies, effects cellular processes in a cell specific manner, can have far reaching consequences on the development of smart biomaterials especially for directing stem cell differentiation

Automated psychological therapy using immersive virtual reality for treatment of fear of heights: A single-blind, parallel-group, randomised controlled trial

Background Engaging, interactive, and automated virtual reality (VR) treatments might help solve the unmet needs of individuals with mental health disorders. We tested the efficacy of an automated cognitive intervention for fear of heights guided by an avatar virtual coach (animated using motion and voice capture of an actor) in VR and delivered with the latest consumer equipment. Methods We did a randomised trial of automated VR versus usual care. We recruited adults aged older than 18 years with a fear of heights by radio advertisements in Oxfordshire, UK. We diagnosed fear of heights if participants scored more than 29 on the Heights Interpretation Questionnaire (HIQ). We randomly allocated participants by computer in a 1:1 ratio to either automated VR delivered in roughly six 30-min sessions administered about two to three times a week over a 2-week period (intervention group) or to usual care (control group). Randomisation was stratified by severity of fear of heights. The research team, who were unaware of the random allocation, administered three fear-of-height assessments, at baseline (0 weeks), at the end of treatment (2 weeks), and at follow-up (4 weeks). The primary outcome measure was HIQ score (range 16–80, with higher scores indicating greater severity). This trial is registered with the ISRCTN registry, number ISRCTN11898283. Findings Between Nov 25, 2017, and Feb 27, 2018, 100 individuals were enrolled and underwent randomisation, of whom 49 were assigned to the VR treatment group and 51 to the control group. All participants completed the 4-week follow-up. The mean total treatment time in VR was 124·43 min (SD 34·23). Compared with participants in the control group, the VR treatment reduced fear of heights at the end of treatment (mean change score −24·5 [SD 13·1] in the VR group vs −1·2 [7·3] in the control group; adjusted difference −24·0, 95% CI −27·7 to −20·3; Cohen's d=2·0; p<0·0001). The benefit was maintained at follow-up (mean change score −25·1 [SD 13·9] in the VR group vs −1·5 [7·8] in the control group; adjusted difference −24·3, 95% CI −27·9 to −20·6; Cohen's d=2·0; p<0·0001). The number needed to treat to at least halve the fear of heights was 1·3. No adverse events were reported. Interpretation Psychological therapy delivered automatically by a VR coach can produce large clinical benefits. Evidence-based VR treatments have the potential to greatly increase treatment provision for mental health disorders

Effort Perception is Made More Accurate with More Effort and When Cooperating with Slackers

Recent research on the conditions that facilitate cooperation is limited by a factor that has yet to be established: the accuracy of effort perception. Accuracy matters because the fitness of cooperative strategies depends not just on being able to perceive others' effort but to perceive their true effort. In an experiment using a novel effort-tracker methodology, we calculate the accuracy of human effort perceptions and show that accuracy is boosted by more absolute effort (regardless of relative effort) and when cooperating with a "slacker" rather than an "altruist". A formal model shows how such an effort-prober strategy is likely to be an adaptive solution because it gives would-be collaborators information on when to abort ventures that are not in their interest and opt for ones that are. This serves as a precautionary measure against systematic exploitation by extortionist strategies and a descent into uncooperativeness. As such, it is likely that humans have a bias to minimize mistakes in effort perception that would commit them to a disadvantageous effort-reward relationship. Overall we find support for the idea that humans have evolved smart effort detection systems that are made more accurate by those contexts most relevant for cooperative tasks

How valid are assessments of conception probability in ovulatory cycle research? Evaluations, recommendations, and theoretical implications

Over the past two decades, a large literature examining psychological changes across women's ovulatory cycles has accumulated, emphasizing comparisons between fertile and non-fertile phases of the cycle. While some studies have verified ovulation using luteinizing hormone (LH) tests, counting methods – assessments of conception probability based on counting forward from actual or retrospectively recalled onset of last menses, or backward from actual or anticipated onset of next menses – are more common. The validity of these methods remains largely unexplored. Based on published data on the distributions of the lengths of follicular and luteal phases, we created a sample of 58,000+ simulated cycles. We used the sample to assess the validity of counting methods. Aside from methods that count backward from a confirmed onset of next menses, validities are modest, generally ranging from about .40–.55. We offer power estimates and make recommendations for future work. We also discuss implications for interpreting past research

The role of ground motion duration and pulse effects in the collapse of ductile systems

The seismic collapse capacity of ductile single‐degree‐of‐freedom systems vulnerable to P‐Δ effects is investigated by examining the respective influence of ground motion duration and acceleration pulses. The main objective is to provide simple relationships for predicting the duration‐dependent collapse capacity of modern ductile systems. A novel procedure is proposed for modifying spectrally equivalent records, such that they are also equivalent in terms of pulses. The effect of duration is firstly assessed, without accounting for pulses, by assembling 101 pairs of long and short records with equivalent spectral response. The systems considered exhibit a trilinear backbone curve with an elastic, hardening and negative stiffness segment. The parameters investigated include the period, negative stiffness slope, ductility and strain hardening, for both bilinear and pinching hysteretic models. Incremental dynamic analysis is employed to determine collapse capacities and derive design collapse capacity spectra. It is shown that up to 60% reduction in collapse capacity can occur due to duration effects for flexible bilinear systems subjected to low levels of P‐Δ. A comparative evaluation of intensity measures that account for spectral shape, duration or pulses, is also presented. The influence of pulses, quantified through incremental velocity, is then explicitly considered to modify the long records, such that their pulse distribution matches that of their short spectrally equivalent counterparts. The results show the need to account for pulse effects in order to achieve unbiased estimation of the role of duration in flexible ductile systems, as it can influence the duration‐induced reduction in collapse capacity by more than 20%

Female Fertility Affects Men's Linguistic Choices

We examined the influence of female fertility on the likelihood of male participants aligning their choice of syntactic construction with those of female confederates. Men interacted with women throughout their menstrual cycle. On critical trials during the interaction, the confederate described a picture to the participant using particular syntactic constructions. Immediately thereafter, the participant described to the confederate a picture that could be described using either the same construction that was used by the confederate or an alternative form of the construction. Our data show that the likelihood of men choosing the same syntactic structure as the women was inversely related to the women's level of fertility: higher levels of fertility were associated with lower levels of linguistic matching. A follow-up study revealed that female participants do not show this same change in linguistic behavior as a function of changes in their conversation partner's fertility. We interpret these findings in the context of recent data suggesting that non-conforming behavior may be a means of men displaying their fitness as a mate to women