Balance Control and Exercise-Based Interventions in Older Adults

Loss of balance and consequential falling, caused by natural degenerations in the sensory and motor systems with aging, are critical issues that require constant research exploration to ultimately improve the quality of life in older populations. Balance can be simply classified into static and dynamic balance, and the latter is more associated with common causes of falling in older adults. There are numerous ways to improve dynamic balance, and exercise training has been considered the most beneficial intervention for that purpose. Specifically, aquatic exercises have been suggested as a promising modality because several properties of water, including buoyance and hydrostatic pressure, impart direct benefits to older adults during the exercise. However, it is still inconclusive whether aquatic exercises are more effective than land exercises at improving dynamic balance. Further, slips and trips are the most predominant causes of falls in older adults, and they often require a rapid, accurate action to avoid a potential fall. This process is called reactive balance (i.e., compensatory balance reaction). It also can be enhanced by exercise interventions; however, it is unclear what type of exercise is most effective at improving reactive balance. In this dissertation, we compared the impacts of exercise environments on dynamic balance, and then explored what type of exercise intervention improves reactive balance the most in older adults. These studies revealed that both aquatic and land exercises have equivalent effects on improving dynamic balance, and reactive balance improved most successfully after one or more reactive balance exercises were provided. In addition, power training was the second most effective intervention for improving reactive balance. The findings from this dissertation suggest that when exercise-based interventions are used to improve dynamic balance, the exercise environments can be selected based on the purpose of the intervention or each participant’s subjective decision. Moreover, practitioners may wish to implement task-specific reactive balance training on the preferential basis for the intervention aiming at reactive balance. Also, power training, which reflects the mechanism of the targeted reactive balance task, can be jointly or adjunctly utilized to improve reactive balance, which is critical for decreasing falls in older adults

Effects of Height Increasing Heel Insole on Lower Extremity Joint Mechanics

High-heel shoes alter foot pressure distribution and lower extremity kinetic and kinematics. Unlike general women’s high-heeled shoes, height increasing heel insoles are cushioned, which may contribute to impact absorption. The purpose of this study is to compare the kinetic and kinematics of gaits with and without height increasing heel insoles. Two male subjects performed level walking under two conditions: wearing sports shoes with and without height increasing heel insoles which added additional 5 cm of the heel height (total 6 cm). The vertical ground reaction force (GRF), angle, moment, and power of ankle, knee, and hip during the stance phase of the right foot were calculated. As results, higher heel height decreased the GRF under the heel and increased the GRF under the forefoot. The overall plantarflexed foot posture during the stance phase led to the overall reduction in the peak plantar flexor moment, which was persisted into the terminal stance. Also, it limited the power output and concentric contraction of the plantar flexor muscles, including gastrocnemius and soleus. The angle, moment, and power of the knee and hip were similar for both heel height conditions. Walking with height increasing heel insoles caused changes in ankle kinetic and kinematics that begin in the early stance phase. Increased heel height altered entire ankle angle during the stance phase, caused more plantarflexion, and shortened gastrocnemius and soleus muscles. Therefore, the propulsive ability was restricted, leading to the decreases of ankle moment and power

Reliable postprocessing improvement of van der Waals heterostructures

The successful assembly of heterostructures consisting of several layers of different 2D materials in arbitrary order by exploiting van der Waals forces has truly been a game changer in the field of low dimensional physics. For instance, the encapsulation of graphene or MoS2 between atomically flat hexagonal boron nitride (hBN) layers with strong affinity and graphitic gates that screen charge impurity disorder provided access to a plethora of interesting physical phenomena by drastically boosting the device quality. The encapsulation is accompanied by a self-cleansing effect at the interfaces. The otherwise predominant charged impurity disorder is minimized and random strain fluctuations ultimately constitute the main source of residual disorder. Despite these advances, the fabricated heterostructures still vary notably in their performance. While some achieve record mobilities, others only possess mediocre quality. Here, we report a reliable method to improve fully completed van der Waals heterostructure devices with a straightforward post-processing surface treatment based on thermal annealing and contact mode AFM. The impact is demonstrated by comparing magnetotransport measurements before and after the AFM treatment on one and the same device as well as on a larger set of treated and untreated devices to collect device statistics. Both the low temperature properties as well as the room temperature electrical characteristics, as relevant for applications, improve on average substantially. We surmise that the main beneficial effect arises from reducing nanometer scale corrugations at the interfaces, i.e. the detrimental impact of random strain fluctuations

Even denominator fractional quantum Hall states in higher Landau levels of graphene

An important development in the field of the fractional quantum Hall effect has been the proposal that the 5/2 state observed in the Landau level with orbital index $n = 1$ of two dimensional electrons in a GaAs quantum well originates from a chiral $p$-wave paired state of composite fermions which are topological bound states of electrons and quantized vortices. This state is theoretically described by a "Pfaffian" wave function or its hole partner called the anti-Pfaffian, whose excitations are neither fermions nor bosons but Majorana quasiparticles obeying non-Abelian braid statistics. This has inspired ideas on fault-tolerant topological quantum computation and has also instigated a search for other states with exotic quasiparticles. Here we report experiments on monolayer graphene that show clear evidence for unexpected even-denominator fractional quantum Hall physics in the $n=3$ Landau level. We numerically investigate the known candidate states for the even-denominator fractional quantum Hall effect, including the Pfaffian, the particle-hole symmetric Pfaffian, and the 221-parton states, and conclude that, among these, the 221-parton appears a potentially suitable candidate to describe the experimentally observed state. Like the Pfaffian, this state is believed to harbour quasi-particles with non-Abelian braid statistic

Effort and Prospective on Nuclear Security in ROK

As of July 2013, the Republic of Korea (ROK) has been operating a total of 23 nuclear power reactors at four sites with five new reactors under construction. In addition, the country has been planned to construct two more units at two candidate sites. But, at now, due to change the energy policy, only one candidate site has been constructed and one nuclear power plant has been decommissioned. Otherwise, ROK has also been exporting nuclear power plants to the United Arab Emirates (UAE) and building a research reactor to Jordan. These performances have made the nation’s nuclear industry by far the fastest growing industry in the world. While Korea has focused on improvements in the field of nuclear safety (especially after the Fukushima accident), it continues to strengthen nuclear security as well. This was demonstrated when the country hosted the 2012 Nuclear Security Summit and in a speech made by nation’s president emphasizing the need for nuclear and cyber security during the 2014 Nuclear Security Summit(NSS). The paper examined the approaches leading to the establishment of the physical protection systems applied at the nuclear facilities in ROK based on CPPNM. Also, the paper will offer recommendations for further steps to improve the ROK’s existing nuclear security apparatus

New satellite climate data records indicate strong coupling between recent frozen season changes and snow cover over high northern latitudes

We examined new satellite climate data records documenting frozen (FR) season and snow cover extent (SCE) changes from 1979 to 2011 over all northern vegetated land areas (≥45 °N). New insight on the spatial and temporal characteristics of seasonal FR ground and snowpack melt changes were revealed by integrating the independent FR and SCE data records. Similar decreasing trends in annual FR and SCE durations coincided with widespread warming (0.4 °C decade−1). Relatively strong declines in FR and SCE durations in spring and summer are partially offset by increasing trends in fall and winter. These contrasting seasonal trends result in relatively weak decreasing trends in annual FR and SCE durations. A dominant SCE retreat response to FR duration decreases was observed, while the sign and strength of this relationship was spatially complex, varying by latitude and regional snow cover, and climate characteristics. The spatial extent of FR conditions exceeds SCE in early spring and is smaller during snowmelt in late spring and early summer, while FR ground in the absence of snow cover is widespread in the fall. The integrated satellite record, for the first time, reveals a general increasing trend in annual snowmelt duration from 1.3 to 3.3 days decade−1 (p \u3c 0.01), occurring largely in the fall. Annual FR ground durations are declining from 0.8 to 1.3 days decade−1. These changes imply extensive biophysical impacts to regional snow cover, soil and permafrost regimes, surface water and energy budgets, and climate feedbacks, while ongoing satellite microwave missions provide an effective means for regional monitoring

An extended global Earth system data record on daily landscape freeze–thaw status determined from satellite passive microwave remote sensing

The landscape freeze–thaw (FT) signal determined from satellite microwave brightness temperature (Tb) observations has been widely used to define frozen temperature controls on land surface water mobility and ecological processes. Calibrated 37 GHz Tb retrievals from the Scanning Multichannel Microwave Radiometer (SMMR), Special Sensor Microwave Imager (SSM/I), and SSM/I Sounder (SSMIS) were used to produce a consistent and continuous global daily data record of landscape FT status at 25 km grid cell resolution. The resulting FT Earth system data record (FT-ESDR) is derived from a refined classification algorithm and extends over a larger domain and longer period (1979–2014) than prior FT-ESDR releases. The global domain encompasses all land areas affected by seasonal frozen temperatures, including urban, snow- and ice-dominant and barren land, which were not represented by prior FT-ESDR versions. The FT retrieval is obtained using a modified seasonal threshold algorithm (MSTA) that classifies daily Tb variations in relation to grid-cell-wise FT thresholds calibrated using surface air temperature data from model reanalysis. The resulting FT record shows respective mean annual spatial classification accuracies of 90.3 and 84.3 % for evening (PM) and morning (AM) overpass retrievals relative to global weather station measurements. Detailed data quality metrics are derived characterizing the effects of sub-grid-scale open water and terrain heterogeneity, as well as algorithm uncertainties on FT classification accuracy. The FT-ESDR results are also verified against other independent cryospheric data, including in situ lake and river ice phenology, and satellite observations of Greenland surface melt. The expanded FT-ESDR enables new investigations encompassing snow- and ice-dominant land areas, while the longer record and favorable accuracy allow for refined global change assessments that can better distinguish transient weather extremes, landscape phenological shifts, and climate anomalies from longer-term trends extending over multiple decades. The dataset is freely available online (doi:10.5067/MEASURES/CRYOSPHERE/nsidc-0477.003)