Extracting Visibility Information by Following Walls

This paper presents an analysis of a simple robot model, called Bitbot. The Bitbot has limited capabilities; it can reliably follow walls and sense a contact with a wall. Although the Bitbot does not have a range sensor or a camera, it is able to acquire visibility information from the environment, which is then used to solve a pursuit-evasion task. Our developments are centered on the characterization of the information the Bitbot acquires. At any given moment, due to the sensing uncertainty, the robot does not know the current state. In general, uncertainty in the state is one of the central issues in robotics; the Bitbot model serves as an example of how the notion of information space naturally handles uncertainty. We show that state estimation with the Bitbot is a challenging problem, related to the well-known open problem of characterizing visibility graphs in computational geometry. However, state estimation becomes unnecessary to the achievement of the Bitbot\u27s visibility tasks. We show how pursuit-evasion strategy is derived from a careful manipulation with histories of observations, and present analysis of the algorithm and experimental results

Maternal Stress and Excessive Weight Gain in Infancy

Rapid weight gain in infancy increases the risk of developing obesity early in life and contributes significantly to racial and ethnic disparities in childhood obesity. While maternal perceived stress is associated with childhood obesity, little is known about the impact it has on infant weight gain. Therefore, this study explores the impact of maternal perceived stress on change in weight-for-length (WFL) z-scores and the risk of rapid weight gain in infancy. We conducted a secondary data analysis of the longitudinal Nurture birth cohort (n = 666). Most mothers in the cohort were non-Hispanic/Latinx Black (71.6%). About one-half of mothers had a body mass index (BMI) greater than 25 prior to pregnancy, were unemployed, and had a low income. Most infants in the cohort were born full-term and were of normal weight. Data were collected at 3-, 6-, 9-, and 12-months postpartum. At each assessment, mothers completed the Cohen’s Perceived Stress Scale (PSS), and research assistants weighed and measured each infant. Tertiles were used to compare mothers with high and low perceived stress. A mixed model analysis of repeated measures assessed the associations between baseline perceived stress and the change in infant WFL z-scores over time. Log-binomial models assessed the association between baseline perceived stress and rapid weight gain, defined as a change in WFL z-score \u3e 0.67 standard deviations from three to twelve months. Just under one-half of the infants (47%) experienced rapid weight gain between three and twelve months of age. Birthweight for gestational age (RR = 1.18, 95% CI = 1.08–1.29, p-value = 0.004), gestational age at birth (RR = 1.07, 95% CI = 1.01–1.14, p-value = 0.031), and weeks breastfed (0.99, 95% CI 0.99–1.00, p-value 0.044) were associated with risk of rapid weight gain in unadjusted analyses. WFL z-scores increased significantly over time, with no effect of perceived stress on change in WFL z-score or risk of rapid weight gain. Rapid weight gain in infancy was prevalent in this sample of predominately Black infants in the Southeastern US. We did not find evidence to support the hypothesis that maternal perceived stress influenced the risk of rapid weight gain. More work is needed to identify and assess the risk factors for rapid weight gain in infancy and to understand the role that maternal stress plays in the risk of childhood obesity so that prevention efforts can be targeted

Associations of less healthy snack food consumption with infant weight-for-length z-score trajectories: Findings from the Nurture cohort study

Little is known about the impact of less healthy snack foods on weight trajectories during infancy. This secondary analysis of data from the Nurture cohort explored prospective associations of less healthy snack foods with infant weight trajectories. Pregnant women were recruited and, upon delivery of a single live infant, 666 mothers agreed to participate. Mothers completed sociodemographic and infant feeding questionnaires, and infant anthropometrics were collected during home visits at 3, 6, 9, and 12 months. Less healthy snack food consumption was assessed by asking how frequently baby snacks and sweets were consumed each day during the previous three months. Multilevel growth curve models explored associations of baby snacks and sweets with infant weight-for-length (WFL) z-scores. On average, mothers were 27 years old, 71.5% were non-Hispanic Black, and 55.4% had household incomes of ≤$20,000/year. Consumption of less healthy snack foods increased during infancy with a median intake of 3.0 baby snacks/day and 0.7 sweets/day between 10 and 12 months. Growth curve models showed that infants who consumed sweets \u3e2 times/day had significantly higher WFL z-scores during the second half of infancy compared to infants who never consumed sweets. Less healthy snacks may contribute to the risk of obesity during infancy and promoting healthy snack food choices during this critical time is important

Pressurized Device for Mitigating Atrophy in Soleus During Long-Duration Spaceflight

A major concern with long duration spaceflight, skeletal muscle atrophy is most detrimental in lower limb musculature, particularly in muscles critical for proper gait, such as the soleus. The decline of muscle activation and the suppression of sensory input from plantar sole mechanoreceptors can add to the attenuation of skeletal muscle health during spaceflight. More specifically, inhibition of sensory input from sole receptors, such as with gravitational unloading, decreases selective activation, thereby negatively affecting muscle tone and inevitably resulting in lower limb atrophy. PURPOSE: To design, fabricate, and test a specialized boot with an insole that applies oscillating pneumatic pressure for set periods of time to augment neuromuscular activation of the soleus through the plantar sole\u27s mechanoreceptors, which may minimize atrophy of lower extremity muscles. METHODS: The custom boot was originally designed in three-dimensional modeling software (Solidworks Premium, Waltham, MA). Components of the boot included: a lightweight medical walking brace, Metro-ATmega circuit board, air pump and vacuum DC motor, force resistive sensor, and kPa sensor. The boot was programmed using C++ to allow the user to wear the boot for 20 minutes (oscillating continuously) at the start of every hour with an automatic timer for 6 hours per day. Surface electromyography (EMG) measured electrical activity in lower extremity muscles while wearing the boot. The location of all electrodes were determined according to the SENIAM project (Surface Electromyography for the Non-Invasive Assessment of Muscles): 1) for soleus, electrode placed at two-thirds of the line between the medial condyle of the femur to the medial malleolus; 2) for medial head of the gastrocnemius, electrode placed at one-third of the line between the head of the fibula and the heel; 3) for ground, electrode placed at the tibial tuberosity. Muscle activation of the gastrocnemius was measured to investigate any co-activation of nearby musculature on the posterior leg. RESULTS: Upon airbag inflation, the soleus exhibited the greatest amplitude (30 to 50 µV versus 5 to 15 µV) when the ankle attempted to plantarflex while maintaining a neutral position. When the airbags are inflated, the pressure output corresponds to approximately 111 kPa. When the airbags are deflated, the pressure output corresponds to approximately 66 kPa, creating a pressure difference of 45 kPa. During the 20 min runtime, the airbags take 3.3 sec to inflate and 3.0 sec to deflate, creating the oscillating effect. When fully charged, the battery can sustain one full, 6-hour session with each lasting 20 minutes. CONCLUSION: Pneumatic pressure integrated into a customized therapeutic walking boot may elicit neuromuscular activity in the lower extremity musculature, which indicates that the device may help in attenuating the negative neuromuscular adaptations in the soleus via afferent signaling

A multiplatform experiment to unravel meso- and submesoscale processes in an intense front (AlborEx).

© The Authors, 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Pascual, A., Ruiz, S., Olita, A., Troupin, C., Claret, M., Casas, B., Mourre, B., Poulain, P. M., Tovar-Sanchez, A., Capet, A., Mason, E., Allen, J. T., Mahadevan, A., & Tintore, J. A multiplatform experiment to unravel meso- and submesoscale processes in an intense front (AlborEx). Frontiers in Marine Science, 4(39), (2017), doi:10.3389/fmars.2017.00039.The challenges associated with meso- and submesoscale variability (between 1 and 100 km) require high-resolution observations and integrated approaches. Here we describe a major oceanographic experiment designed to capture the intense but transient vertical motions in an area characterized by strong fronts. Finescale processes were studied in the eastern Alboran Sea (Western Mediterranean) about 400 km east of the Strait of Gibraltar, a relatively sparsely sampled area. In-situ systems were coordinated with satellite data and numerical simulations to provide a full description of the physical and biogeochemical variability. Hydrographic data confirmed the presence of an intense salinity front formed by the confluence of Atlantic Waters, entering from Gibraltar, with the local Mediterranean waters. The drifters coherently followed the northeastern limb of an anticyclonic gyre. Near real time data from acoustic current meter data profiler showed consistent patterns with currents of up to 1 m/s in the southern part of the sampled domain. High-resolution glider data revealed submesoscale structures with tongues of chlorophyll-a and oxygen associated with the frontal zone. Numerical results show large vertical excursions of tracers that could explain the subducted tongues and filaments captured by ocean gliders. A unique aspect of AlborEx is the combination of high-resolution synoptic measurements of vessel-based measurements, autonomous sampling, remote sensing and modeling, enabling the evaluation of the underlying mechanisms responsible for the observed distributions and biogeochemical patchiness. The main findings point to the importance of fine-scale processes enhancing the vertical exchanges between the upper ocean and the ocean interior.The AlborEx experiment was conducted in the framework of PERSEUS EU-funded project (Grant agreement no: 287600). The experiment was led by the Spanish National Research Council (CSIC) institution with strong involvement and cooperation from other national and international partners: Balearic Islands Coastal Observing and Forecasting System (SOCIB, Spain); Consiglio Nazionale delle Ricerche (CNR, Italy), McGill University (Canada); Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS, Italy) and Woods Hole Oceanographic Institution (WHOI, USA). Glider operations were partially funded by JERICO FP7 project. AP acknowledges support from the Spanish National Research Program (E-MOTION/CTM2012-31014 and PRE-SWOT/CTM2016-78607-P). SR and AP are also supported by the Copernicus Marine Environment Monitoring Service (CMEMS) MedSUB project. EM is supported by a post-doctoral grant from the Conselleria d'Educació, Cultura i Universitats del Govern de les Illes Balears (Mallorca, Spain) and the European Social Fund. AC is a FNRS researcher under the FNRS BENTHOX project (Convention T.1009.15). The altimeter products were produced by Ssalto/Duacs and distributed by CMEMS. The profiling floats and some drifters were contributed by the Argo-Italy program. The authors are in debt with A. Massanet, F. Margirier, M. Palmer, C. Castilla, P. Balaguer and for their efficient work and implication during the AlborEx cruise. We also thank M. Menna, G. Notarstefano and A. Bussani for their help with the drifter and float data processing and the production of some figures. This article was initiated during a research visit of the first two authors to Woods Hole Oceanographic Institution

Provider Reported Implementation of Nutrition-related Practices in Childcare Centers and Family Childcare Homes in Rural and Urban Nebraska

Approximately 15 million children under age 6 are in childcare settings, offering childcare providers an opportunity to influence children’s dietary intake. Childcare settings vary in organizational structure – childcare centers (CCCs) vs. family childcare homes (FCCHs) – and in geographical location – urban vs. rural. Research on the nutrition-related best practices across these childcare settings is scarce. The objective of this study is to compare nutrition-related best practices of CCCs and FCCHs that participate in the Child and Adult Care Food Program (CACFP) in rural and urban Nebraska. Nebraska providers (urban n = 591; rural n = 579) reported implementation level, implementation difficulty and barriers to implementing evidence-informed food served and mealtime practices. Chi-square tests comparing CCCs and FCCHs in urban Nebraska and CCCs and FCCHs in rural Nebraska showed sub-optimal implementation for some practices across all groups, including limiting fried meats and high sugar/ high fat foods, using healthier foods or non-food treats for celebrations and serving meals family style. Significant differences (p \u3c .05) between CCCs and FCCHs also emerged, especially with regard to perceived barriers to implementing best practices. For example, CCCs reported not having enough money to cover the cost of meals for providers, lack of control over foods served and storage problems, whereas FCCHs reported lack of time to prepare healthier foods and sit with children during mealtimes. Findings suggest that policy and public health interventions may need to be targeted to address the unique challenges of implementing evidence-informed practices within different organizational structures and geographic locations

Cluster K Mycobacteriophages: Insights into the Evolutionary Origins of Mycobacteriophage TM4

Five newly isolated mycobacteriophages –Angelica, CrimD, Adephagia, Anaya, and Pixie – have similar genomic architectures to mycobacteriophage TM4, a previously characterized phage that is widely used in mycobacterial genetics. The nucleotide sequence similarities warrant grouping these into Cluster K, with subdivision into three subclusters: K1, K2, and K3. Although the overall genome architectures of these phages are similar, TM4 appears to have lost at least two segments of its genome, a central region containing the integration apparatus, and a segment at the right end. This suggests that TM4 is a recent derivative of a temperate parent, resolving a long-standing conundrum about its biology, in that it was reportedly recovered from a lysogenic strain of Mycobacterium avium, but it is not capable of forming lysogens in any mycobacterial host. Like TM4, all of the Cluster K phages infect both fast- and slow-growing mycobacteria, and all of them – with the exception of TM4 – form stable lysogens in both Mycobacterium smegmatis and Mycobacterium tuberculosis; immunity assays show that all five of these phages share the same immune specificity. TM4 infects these lysogens suggesting that it was either derived from a heteroimmune temperate parent or that it has acquired a virulent phenotype. We have also characterized a widely-used conditionally replicating derivative of TM4 and identified mutations conferring the temperature-sensitive phenotype. All of the Cluster K phages contain a series of well conserved 13 bp repeats associated with the translation initiation sites of a subset of the genes; approximately one half of these contain an additional sequence feature composed of imperfectly conserved 17 bp inverted repeats separated by a variable spacer. The K1 phages integrate into the host tmRNA and the Cluster K phages represent potential new tools for the genetics of M. tuberculosis and related species

Selective Regulation of NR2B by Protein Phosphatase-1 for the Control of the NMDA Receptor in Neuroprotection

An imbalance between pro-survival and pro-death pathways in brain cells can lead to neuronal cell death and neurodegeneration. While such imbalance is known to be associated with alterations in glutamatergic and Ca2+ signaling, the underlying mechanisms remain undefined. We identified the protein Ser/Thr phosphatase protein phosphatase-1 (PP1), an enzyme associated with glutamate receptors, as a key trigger of survival pathways that can prevent neuronal death and neurodegeneration in the adult hippocampus. We show that PP1α overexpression in hippocampal neurons limits NMDA receptor overactivation and Ca2+ overload during an excitotoxic event, while PP1 inhibition favors Ca2+ overload and cell death. The protective effect of PP1 is associated with a selective dephosphorylation on a residue phosphorylated by CaMKIIα on the NMDA receptor subunit NR2B, which promotes pro-survival pathways and associated transcriptional programs. These results reveal a novel contributor to the mechanisms of neuroprotection and underscore the importance of PP1-dependent dephosphorylation in these mechanisms. They provide a new target for the development of potential therapeutic treatment of neurodegeneration