Deficits in dynamic neuromuscular control have been associated with post-injury sequelae and increased injury risk. The Y-Balance Test Lower Quarter (YBT-LQ) has emerged as a tool to identify these ...deficits.
To review the reliability of the YBT-LQ, determine if performance on the YBT-LQ varies among populations (i.e., sex, sport/activity, and competition level), and to determine the injury risk identification validity of the YBT-LQ based on asymmetry, individual reach direction performance, or composite score.
Systematic Review.
A comprehensive search was performed of 10 online databases from inception to October 30, 2019. Only studies that tested dynamic single leg balance using the YBT-LQ were included. Studies were excluded if the Y-Balance Test kit was not utilized during testing or if there was a major deviation from the Y-Balance test procedure. For methodological quality assessment, the modified Downs and Black scale and the Newcastle-Ottawa Scale were used.
Fifty-seven studies (four in multiple categories) were included with nine studies assessing reliability, 36 assessing population differences, and 16 assessing injury prediction were included. Intra-rater reliability ranged from 0.85-0.91. Sex differences were observed in the posteromedial direction (males: 109.6 95%CI 107.4-111.8; females: 102.3 95%CI 97.2-107.4; p = 0.01) and posterolateral direction (males: 107.0 95%CI 105.0-109.1; females: 102.0 95%CI 97.8-106.2). However, no difference was observed between sexes in the anterior reach direction (males: 71.9 95%CI 69.5-74.5; females: 70.8 95%CI 65.7-75.9; p=0.708). Differences in composite score were noted between soccer (97.6; 95%CI 95.9-99.3) and basketball (92.8; 95%CI 90.4-95.3; p <0.01), and baseball (97.4; 95%CI 94.6-100.2) and basketball (92.8; 95%CI 90.4-95.3; p=0.02). Given the heterogeneity of injury prediction studies, a meta-analysis of these data was not possible. Three of the 13 studies reported a relationship between anterior reach asymmetry reach and injury risk, three of 10 studies for posteromedial and posterolateral reach asymmetry, and one of 13 studies reported relationship with composite reach asymmetry.
There was moderate to high quality evidence demonstrating that the YBT-LQ is a reliable dynamic neuromuscular control test. Significant differences in sex and sport were observed. If general cut points (i.e., not population specific) are used, the YBT-LQ may not be predictive of injury. Clinical population specific requirements (e.g., age, sex, sport/activity) should be considered when interpreting YBT-LQ performance, particularly when used to identify risk factors for injury.
1b.
The Bekaa Valley in Lebanon currently hosts the highest number of refugees per capita in the world. It is also the primary agricultural production area in the country. Groundwater levels in some ...regions of the valley have decreased by >15 m in the last five years. Water use estimates at the regional and the field scale for this valley are crucial for enhancing resilience and for managing competing sectorial water demands. In this research, we derive a novel time series of field-scale actual evapotranspiration for the Bekaa Valley using two one-source energy balance models for the period 1984–2017, utilizing local weather data and all available original Level 1 Landsat thermal imagery and Level 2 surface reflectance products. We compare a modified METRIC model with an automated hot and cold pixel identification procedure run in batch mode to pySEBAL, a new version of SEBAL, which also has its automated anchors pixel selection algorithm. Analysis of 1200 cloud-masked and gap-filled Landsat-derived ET products show that the two models give comparable water use estimates at the seasonal and annual time steps. We estimate an average annual ET of 652 ± 53 mm (or 800 mcm) over the heavily cultivated valley in the last 34 years (with high agreement between both METRIC and pySEBAL models). Most (64%) of the ET is consumed from blue water in the dry season of May–October. ET in the wet season of November–April consumes >70% of the precipitation in the Bekaa valley. Annual analysis shows no discernable trend in ET across the valley, but there is an increase in irrigated agriculture in the Orontes Basin in the last five years. METRIC yields 15% higher ET than pySEBAL for the non-agricultural lands in summer. A water balance analysis shows that groundwater storage in the Litani basin is decreasing at a rate of 330 ± 50 mm yr−1. The outcome of this research also offers unique opportunities for estimating past and future trends of groundwater withdrawals. Results can provide insights into the sustainability of irrigated agriculture and the required international interventions in the water sector for enhancing the resilience of refugee and local communities.
•Full Landsat thermal collection utilized to generate field-scale ET in Lebanon.•Automated anchor pixel selection applied in METRIC and pySEBAL on 1200 scenes.•Peak water use of 500 mcm in the Bekaa is between April and August.•No trends in time series ET determined for the Bekaa Valley for 1984–2017.•Non-renewable aquifer depletion ranges from 280 to 380 mm per year.
Current observational data on Hindu Kush Himalayas (HKH) glaciers
are sparse, and characterizations of seasonal melt dynamics are limited.
Time series synthetic aperture radar (SAR) imagery enables ...detection of
reach-scale glacier melt characteristics across continents. We analyze
C-band Sentinel-1 A/B SAR time series data, comprised of 32 741 Sentinel-1
A/B SAR images, and determine the duration of seasonal glacier melting for
105 432 mapped glaciers (83 102 km2 glacierized area, defined using
optical observations) in the HKH across the calendar years 2017–2019. Melt
onset and duration are recorded at 90 m spatial resolution and 12 d
temporal repeat. All glacier areas within the HKH exhibit some degree of
melt. Melt signals persist for over two-thirds of the year at elevations below
4000 m a.s.l. and for nearly half of the calendar year at elevations
exceeding 7000 m a.s.l. Retrievals of seasonal melting span all elevation
ranges of glacierized area in the HKH region, extending greater than 1 km
above the maximum elevation of an interpolated 0 ∘C summer
isotherm and at the top of Mount Everest, where in situ data and surface energy
balance models indicate that the Khumbu Glacier is melting at surface air
temperatures below −10 ∘C. Sentinel-1 melt retrievals
reflect broad-scale trends in glacier mass balance across the region, where
the duration of melt retrieved in the Karakoram is on
average 16 d less than in the eastern Himalaya sub-region. Furthermore,
percolation zones are apparent from meltwater retention indicated by delayed
refreeze. Time series SAR datasets are suitable to support operational
monitoring of glacier surface melt and the development and assessment of
surface energy balance models of melt-driven ablation across the global
cryosphere.
A distributed mass-balance model is used over a 10-year period for the re-analysis of a glaciological mass-balance time series obtained from Brewster Glacier, New Zealand. Mass-balance modelling ...reveals glaciological mass balance has been overestimated, with an average mass loss of −516 mm w.e. a−1 not captured by observations at the end of the ablation season, which represents 35% of the annual mass balance. While the average length of the accumulation season (199 days) remains longer than the ablation season (166 days), melting is not uncommon in the core part of the accumulation season, with 2–32% of total snowfall being melted. Refreezing of meltwater is also important, with 10% of surface and subsurface melt being refrozen in the present climate. Net radiation, driven primarily by net shortwave radiation, is the main contributor to melt energy, with melt variability mainly influenced by the turbulent heat fluxes, net longwave radiation and the heat flux from precipitation in the ablation season. Snowfalls in summer are an important moderator of melt, highlighting the critical role of the ice-albedo feedback and phase of precipitation on seasonal mass balance. A complete homogenisation of the long-term glaciological mass balance for Brewster Glacier is still required.
Multiple sclerosis (MS) is a chronic inflammatory demyelinating disorder in which lymphocytic infiltration mediated mainly by pro-inflammatory cytokines. In this study, we examined the effect of ...combined exercise training on the levels of IFN-g, IL-4 and IL-17 in the plasma and the supernatant of peripheral blood lymphocytes in women with multiple sclerosis. Expanded Disability Status Scale (EDSS), VO sub(2)max, muscle strength, and balance tests were obtained at baseline and post-treatment follow-up. Combined exercises training was designed for 24 sessions during 8 weeks. Each session was started with 5 min warm-up and was followed by 10 min stretch training, 20 min aerobic exercises and 20 min resistance-endurance training. The disability score was significantly decreased in test MS subjects after 8 weeks combined exercise training. Muscle strength and balance were increased significantly after the training program in test group. In this study, plasma, and peripheral blood mononuclear cell (PBMC) IL-17 and IFN-g production was significantly decreased after 8 weeks combined training. Our findings suggest that combined training has useful anti-inflammatory effects by decrease in PBMC and plasma IL-17 production.
Despite their importance for regional water resource planning and as indicators of climate change, records of in situ glacier mass balance remain short and spatially sparse in the Himalaya. Here, we ...present an updated series of in situ mass-balance measurements from Rikha Samba Glacier, Nepal, between 2011 and 2021. The updated in situ mass balance is −0.39 ± 0.32 m w.e. for this period. We use an energy-mass balance model to extend the annual mass-balance series back to 1974. The model is forced using daily meteorological variables from ERA5-Land reanalysis data that is linearly bias-corrected using observations from an automatic weather station situated near the glacier terminus. The modeled mass balance is consistent with the in situ mass-balance series measured 2011–2021 and with previous glaciological and geodetic estimates. The model results indicate a mass balance of −0.56 ± 0.27 m w.e. a−1 over the reconstruction period of 1974–2021, which is comparable to the mass losses experienced by other Himalayan glaciers during this time. An assessment of the sensitivity of the glacier mass balance to meteorological forcing suggests that a change in temperature of ±1 K has a stronger effect on the calculated mass balance compared to a ±20% change in either precipitation, or relative humidity, or solar radiation.
The Antarctic ice sheet mass balance is a major component of the sea level
budget and results from the difference of two fluxes of a similar magnitude:
ice flow discharging in the ocean and net snow ...accumulation on the ice sheet
surface, i.e. the surface mass balance (SMB). Separately modelling ice
dynamics and SMB is the only way to project future trends.
In addition, mass balance studies frequently use regional climate models
(RCMs) outputs as an alternative to observed fields because SMB observations
are particularly scarce on the ice sheet. Here we evaluate new simulations of
the polar RCM MAR forced by three reanalyses, ERA-Interim, JRA-55, and MERRA-2,
for the period 1979–2015, and we compare MAR results to the last outputs of
the RCM RACMO2 forced by ERA-Interim. We show that MAR and RACMO2 perform
similarly well in simulating coast-to-plateau SMB gradients, and we find no
significant differences in their simulated SMB when integrated over the ice
sheet or its major basins. More importantly, we outline and quantify missing
or underestimated processes in both RCMs. Along stake transects, we show that
both models accumulate too much snow on crests, and not enough snow in
valleys, as a result of drifting snow transport fluxes not included in MAR
and probably underestimated in RACMO2 by a factor of 3. Our results tend
to confirm that drifting snow transport and sublimation fluxes are much
larger than previous model-based estimates and need to be better resolved and
constrained in climate models. Sublimation of precipitating particles in
low-level atmospheric layers is responsible for the significantly lower
snowfall rates in MAR than in RACMO2 in katabatic channels at the ice sheet
margins. Atmospheric sublimation in MAR represents 363 Gt yr−1 over the grounded ice sheet for the year 2015, which is 16 %
of the simulated snowfall loaded at the ground. This estimate is consistent
with a recent study based on precipitation radar observations and is more
than twice as much as simulated in RACMO2 because of different time
residence of precipitating particles in the atmosphere. The remaining spatial
differences in snowfall between MAR and RACMO2 are attributed to differences
in advection of precipitation with snowfall particles being likely advected too
far inland in MAR.
A plausible simulation of the global energy balance is a first-order requirement for a credible climate model. Here I investigate the representation of the global energy balance in 40 ...state-of-the-art global climate models participating in the Coupled Model Intercomparison Project phase 6 (CMIP6). In the CMIP6 multi-model mean, the magnitudes of the energy balance components are often in better agreement with recent reference estimates compared to earlier model generations on a global mean basis. However, the inter-model spread in the representation of many of the components remains substantial, often on the order of 10–20 Wm
−2
globally, except for aspects of the shortwave clear-sky budgets, which are now more consistently simulated by the CMIP6 models. The substantial inter-model spread in the simulated global mean latent heat fluxes in the CMIP6 models, exceeding 20% (18 Wm
−2
), further implies also large discrepancies in their representation of the global water balance. From a historic perspective of model development over the past decades, the largest adjustments in the magnitudes of the simulated present-day global mean energy balance components occurred in the shortwave atmospheric clear-sky absorption and the surface downward longwave radiation. Both components were gradually adjusted upwards over several model generations, on the order of 10 Wm
−2
, to reach 73 and 344 Wm
−2
, respectively in the CMIP6 multi-model means. Thereby, CMIP6 has become the first model generation that largely remediates long-standing model deficiencies related to an overestimation in surface downward shortwave and compensational underestimation in downward longwave radiation in its multi-model mean.
Lakes and glaciers are widely distributed in the northwestern Tibetan Plateau. A synchronized examination of lake and glacier mass variations there has not previously been conducted, which has ...limited the understanding of the lake water balance and the hydrologic cycle in the region. In this study, we comprehensively examine lake area and volume, and glacier mass changes using multi-sensor satellite data. We find that lake expansion in the northwestern Tibetan Plateau was more robust from 1976 to 2018 when compared to other regions of the plateau, especially for the glacier-fed and endorheic lakes. Lake volume changes show that most of the lakes had an increase in water volume, particularly in 2000–2018 with a total water storage gain of ~28.6 Gt. By using high-resolution KH-9 and TanDEM-X data, we observe that the glacier surface elevation of the western Kunlun Mountains had a slight thinning rate of −0.07 ± 0.16 m/yr in 1973–2000, but a positive rate of 0.002 ± 0.003 m/yr in 2000–2018. The heterogeneous pattern of glacier elevation changes between the north (N) and south (S) slopes are revealed, i.e. -0.02 ± 0.01 m/yr (N) against −0.12 ± 0.03 m/yr (S) in 1973–2000 and − 0.05 ± 0.02 m/yr (N) against 0.06 ± 0.02 m/yr (S) in 2000–2018. Overall, the glaciers trend to a stable state (~0.05 m/yr) in both the south slope of the western Kunlun Mountains and Aru Co regions between 2000 and 2018. Similar patterns are also found for basin-wide examinations of lake storage changes (mass gains) and glacier mass budgets (positive or close to stable). The seasonal snow cover area changes, derived from cloud-free MODIS snow cover products, present a variable and insignificant trend between 2003 and 2017. Snow depth derived from passive microwave remote-sensing data, exhibits a decreasing trend between 1979 and 2015, but the water equivalent could contribute only an insignificant amount to the observed lake changes. The lake water gains, and almost positive glacier mass balance imply that the hydrological cycle in the northwestern Tibetan Plateau has become enhanced.
•A synchronized examination of lake, glacier and snow variations using multi-sensor satellite data.•The lake expansions in the northwestern TP are more robust relative to other regions of the TP.•Both lake and glacier volume changes show mass gains in 2000–2018.•The enhanced hydrological cycle in the northwestern TP was revealed by lake and glacier changes.
In the context of global warming, glacier changes in the Qinghai–Tibet Plateau (QTP) and its surroundings have attracted a great amount of public attention. To date, there have been many studies of ...glacier mass balance across the QTP. However, given that most of the previous studies have focused on a short observation period (2000–2015), and that long-term mass change measurements are available only for some local regions, we utilized declassified KH-9 images and 1 arc-second Shuttle Radar Topography Mission (SRTM) digital elevation models (DEMs) to provide the region-wide mass balance (from the mid-1970s to 2000) for a larger scale (including 11 sample regions) across the QTP and its surroundings. The final results indicate that the glaciers in the northwest of the QTP have shown a less negative or near-zero mass balance, ranging from −0.11 ± 0.13 m w.e. a−1 to 0.02 ± 0.10 m w.e. a−1, compared to those in the southeast part, with a mass balance range of −0.30 ± 0.12 m w.e. a−1 to −0.11 ± 0.14 m w.e. a−1. The most serious mass loss has emerged in the central-eastern Himalaya. Integrating our results with the observations after 2000 suggests that, over the past four decades (mid-1970s to the mid-2010s), the glaciers in the Himalaya, Nyainqêntanglha, and Tanggula mountains, as a whole, have exhibited accelerated mass loss, and the most significant acceleration has occurred in the eastern Nyainqêntanglha. Moreover, the Hindu Raj glaciers have shown a stable rate of continuous mass loss, while a nearly stable or slight mass gain state in the western Kunlun region can be dated back to at least as far as the mid-1970s.
•Glacier mass balances (1975–2000) in the Tibet Plateau are estimated.•Glaciers in the northwest experienced less ice loss than those in the southeast.•The Himalaya-Nyainqêntanglha glaciers showed accelerated mass loss after 2000.•The western Kunlun glaciers have been in a stable state since the mid-1970s.
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