The Comparison of Dual-Tasking and Functional Fitness in Older Females

Context: America’s aging population is growing faster than ever, resulting in increasing challenges for healthcare providers and caregivers. Over 33% of adults aged 65 and older fall annually, and falls are the number one cause of injury-related death in this age group. Assessing fall risk is difficult due to its multifactorial nature, but functional fitness serves as a proxy measure. Women are at a particularly high risk for fall-related injury due to lower bone mineral density and higher fall frequency when compared to males. Fear of falling is also a serious contributor to fall risk, and it affects up to 89% of older adults. Objective: This study investigated the effects of functional fitness on walking speed under dual-tasking conditions. We hypothesized that women who were less functionally fit would experience greater declines in dual-task walking speed. Design: This experiment had a cross-sectional design. Setting: Tests were conducted at a retirement community in northwest Arkansas. Participants: Participants were females over the age of 65 y, with a mean age of 79.6 y. They were recruited on a volunteer basis and divided in two groups of 13 based on functional fitness levels. Interventions: Functional fitness was determined using the 8-foot up-and-go, a measure of agility and dynamic balance. For walking speed assessments, subjects walked a 10-meter distance with 3 meters extra on each end to account for acceleration and deceleration. Speed was measured with a laser timer. Dual-task assessment required subjects to count backwards by threes from a predetermined number. Four protocols with two trials each were used: single-task walking at habitual and maximal speeds, and dual-task walking at habitual and maximal speeds. Main Outcome Measures: The independent variable was functional fitness level (moderate or high). The dependent variables were dual-task walking time and Dual-Task Cost, calculated by subtracting single-task from dual-task walking time. A one-way ANOVA determined differences between dual-task decrement of the habitual and maximal walking speed trials. Statistical significance was set at α=.05. Results: Average 8-foot up-and-go time for the high functioning group was 5.74 seconds. The average time for the moderate functioning group was 8.33 seconds. Dual-task time difference between the two groups for habitual walking was statistically insignificant (p =.789). For maximal speed, dual-task time difference was statistically significant (p =.04). The moderate group exhibited smaller Dual-Task Costs than the high group for both habitual (difference of 1.3 ± 1.5 s) and maximal (difference of 0.3 ± 0.3 s) conditions. These Dual-Task Cost differences were insignificant for usual speed (p = .11) and maximal speed (p = .38) Discussion: The results did not support the hypothesis of Dual-Task Costs being related to functional fitness level. However, there was a significant difference in maximal dual-task speed between the groups. This shows that maximal dual-task walking speed is more closely linked to functional fitness than is habitual dual-task speed

Notch signaling balances adult neural stem cell quiescence and heterogeneity

Adult neurogenesis continues throughout life in the subventricular zone (SVZ) and the subgranular zone (SGZ) of the hippocampal dentate gyrus (DG) of mammals. At the base of adult neurogenesis lie adult neural stem cells (NSCs). These cells can either be found in a dormant, non-dividing state (quiescent) or in a proliferating state (active). Over the last three decades the field of neurogenesis has expanded, but there are still open questions with regards to adult NSC maintenance and potential capacity. Over the course of my PhD studies I addressed three major questions of adult NSC maintenance. (1) What are the differences between active and quiescent NSCs? (2) Do NSCs have similar maintenance factors in the SVZ and the SGZ? (3) What are the capacities of distinct subtypes of NSCs and progenitors to respond to external stimuli? I was able to show that in the adult mouse brain, Notch2 is the gatekeeper of quiescent NSCs in both neurogenic niches, the SVZ and the SGZ. The loss of this Notch paralogue led to the activation of quiescent NSCS and a prolonged and abnormal activation, followed by NSCs exhaustion in the long term. If Notch1 was deleted in addition to Notch2, quiescent and active NSCs are no longer maintained properly and will differentiate to a neural fate. Thus an intricate interplay between Notch1 and Notch2 is needed for adult NSC maintenance in both neurogenic niches. In the SVZ the receptors Notch1 and Notch2 are coexpressed on NSCs. We addressed NSC identity also in the second neurogenic niche, the SGZ, where the receptors are also coexpressed by NSCs. The loss of Notch2 led to the activation of quiescent NSCs and an increased production of neuroblasts. The differential signal requirement for the maintenance of quiescent and active NSCs raises the question, whether these distinct cell populations might have unique functions in response to external physiological and/or pathological stimuli. In order to address this question we characterized the SGZ in great detail at different ages. In the geriatric SGZ active NSCs were lost and the NSCs that remained were quiescent. These quiescent NSCs have the capacity to replenish the active NSC pool upon induction of epileptic seizures. On the other hand, administration of antidepressants left the NSCs unaffected initially. It was the amplifying progenitor pool that responded. In long-chase experiments the NSCs were then reactivated by either the resulting induced changes from the amplifying progenitors or a delay in NSC response. NSC maintenance in the adult murine brain is an intricate mechanism highly dependent on the proper internal and external mechanisms. In the work presented here, I will illustrate the importance of Notch signaling in NSC maintenance and the high level of heterogeneity within the NSC pool and the NSC niche

An EM Approach for Time-Variant Poisson-Gaussian Model Parameter Estimation

International audienceThe problem of estimating the parameters of a Poisson-Gaussian model from experimental data has recently raised much interest in various applications, for instance in confocal fluorescence microscopy. In this context, a field of independent random variables is observed, which is varying both in time and space. Each variable is a sum of two components, one following a Poisson and the other a Gaussian distribution. In this paper, a general formulation is considered where the associated Poisson process is nonstationary in space and also exhibits an exponential decay in time, whereas the Gaussian component corresponds to a stationary white noise with arbitrary mean. To solve the considered parametric estimation problem, we follow an iterative Expectation-Maximization (EM) approach. The parameter update equations involve deriving finite approximation of infinite sums. Expressions for the maximum error incurred in the process are also given. Since the problem is non-convex, we pay attention to the EM initialization, using a moment-based method where recent optimization tools come into play. We carry out a performance analysis by computing the Cramer-Rao bounds on the estimated variables. The practical performance of the proposed estimation procedure is illustrated on both synthetic data and real fluorescence macroscopy image sequences. The algorithm is shown to provide reliable estimates of the mean/variance of the Gaussian noise and of the scale parameter of the Poisson component, as well as of its exponential decay rate. In particular, the mean estimate of the Poisson component can be interpreted as a good-quality denoised version of the data

Poisson-Gaussian noise parameter estimation in fluorescence microscopy imaging

International audienceIn this paper, we present a new fully automatic approach for noise parameter estimation in the context of fluorescence imaging systems. In particular, we address the problem of Poisson-Gaussian noise modeling in the nonstationary case. In microscopy practice, the nonstationarity is due to the photobleaching effect. The proposed method consists of an adequate moment based initialization followed by Expectation-Maximization iterations. This approach is shown to provide reliable estimates of the mean and the variance of the Gaussian noise and of the scale parameter of Poisson noise, as well as of the photobleaching rates. The algorithm performance is demonstrated on both synthetic and real fluorescence microscopy image sequences

Future Professional Plans of Students in Higher Education

Recent researches underscore the importance of good teachers in ensuring the quality of an educational system (Mourshed & Barber, 2007; Mourshed, Chijioke & Barber, 2010). At the same time we can see that pre-service teachers have poorer academic performan ce and less interest in PhD studies than other stud ents in most European countries. This phenomenon seems to be related to the feminization of the teaching profession. For instance, obtaining a higher academ ic degree is typically a masculine career strategy; when female students and employees try to enhance their cultural capital, they tend to choose courses on the same level of education, instead of innovative doct oral training and researches

Satellites of Milky Way- and M31-like galaxies with TNG50: Quenched fractions, gas content, and star formation histories

We analyse the quenched fractions, gas content, and star formation histories of ∼1200 satellite galaxies with M* ≥ 5 × 106 M⊙ around 198 Milky Way- (MW) and Andromeda-like (M31) hosts in TNG50, the highest-resolution simulation of IllustrisTNG. Satellite quenched fractions are larger for smaller masses, for smaller distances to their host galaxy, and in the more massive M31-like compared to MW-like hosts. As satellites cross their host’s virial radius, their gas content drops: most satellites within 300 kpc lack detectable gas reservoirs at z = 0, unless they are massive like the Magellanic Clouds and M32. Nevertheless, their stellar assembly exhibits a large degree of diversity. On average, the cumulative star formation histories are more extended for brighter, more massive satellites with a later infall, and for those in less massive hosts. Based on these relationships, we can even infer infall periods for observed MW and M31 dwarfs: e.g. 0–4 Gyr ago for the Magellanic Clouds and Leo I, 4 − 8 and 0–2 Gyr ago for M32 and IC 10, respectively. Ram pressure stripping (in combination with tidal stripping) deprives TNG50 satellites of their gas reservoirs and ultimately quenches their star formation, even though only a few per cent of the present-day satellites around the 198 TNG50 MW/M31-like hosts appear as jellyfish. The typical time since quenching for currently quenched TNG50 satellites is 6.9+2.5−3.3 Gyr ago. The TNG50 results are consistent with the quenched fractions and stellar assembly of observed MW and M31 satellites, however, satellites of the SAGA survey with M* ∼ 108 − 9 M⊙ exhibit lower quenched fractions than TNG50 and other, observed analogues

A Concept Study for Feature Extraction and Modeling for Grapevine Yield Prediction

Yield prediction in viticulture is an especially challenging research direction within the field of yield prediction. The characteristics that determine annual grapevine yields are plentiful, difficult to obtain, and must be captured multiple times throughout the year. The processes currently used in grapevine yield prediction are based mainly on manually captured data and rigid statistical measures derived from historical insights. Experts for data acquisition are scarce, and statistical models cannot meet the requirements of a changing environment, especially in times of climate change. This paper contributes a concept on how to overcome those drawbacks, by (1) proposing a deep learning driven approach for feature recognition and (2) explaining how Extreme Gradient Boosting (XGBoost) can be utilized for yield prediction based on those features, while being explainable and computationally inexpensive. The methods developed will be influential for the future of yield prediction in viticulture

The Cellular and Physiological Basis for Lung Repair and Regeneration: Past, Present, and Future.

The respiratory system, which includes the trachea, airways, and distal alveoli, is a complex multi-cellular organ that intimately links with the cardiovascular system to accomplish gas exchange. In this review and as members of the NIH/NHLBI-supported Progenitor Cell Translational Consortium, we discuss key aspects of lung repair and regeneration. We focus on the cellular compositions within functional niches, cell-cell signaling in homeostatic health, the responses to injury, and new methods to study lung repair and regeneration. We also provide future directions for an improved understanding of the cell biology of the respiratory system, as well as new therapeutic avenues

A Cost Comparison Analysis of Bird-Monitoring Techniques for Result-Based Payments in Agriculture

Result-based payments (RBPs) reward land users for conservation outcomes and are a promising alternative to standard payments, which are targeted at specific land use measures. A major barrier to the implementation of RBPs, particularly for the conservation of mobile species, is the substantial monitoring cost. Passive acoustic monitoring may offer promising opportunities for low-cost monitoring as an alternative to human observation. We develop a costing framework for comparing human observation and passive acoustic monitoring and apply it to a hypothetical RBP scheme for farmland bird conservation. We consider three different monitoring scenarios: daytime monitoring for the whinchat and the ortolan bunting, nighttime monitoring for the partridge and the common quail, and day-and-night monitoring for all four species. We also examine the effect of changes in relevant parameters (such as participating area, travel distance and required monitoring time) on the cost comparison. Our results show that passive acoustic monitoring is still more expensive than human observation for daytime monitoring. In contrast, passive acoustic monitoring has a cost advantage for nighttime and day-and-nighttime monitoring in almost all considered scenarios