2,422 research outputs found
Resilience in Quaking Aspen: Recent Advances and Future Needs
Quaking Aspen (Populus tremuloides) sustainability is a topic of intense interest in forest ecology. Reports range from declines to persisting or increasing coverage in some areas. Moreover, there is little agreement on ultimate factors driving changes. Low aspen recruitment has been attributed to climate patterns, past management, herbivore increases, competitive interactions with conifers, predator and beaver extirpation, and livestock grazing. Several of these potential causes result from direct or indirect actions of human agency. On June 27–28, 2012 a group of leading aspen ecologists from diverse backgrounds convened at the High Lonesome Ranch in western Colorado to address the state of aspen science under the title, Resilience in Quaking Aspen: restoring ecosystem processes through applied science. The purposes of this meeting were to: (a) present disciplinary updates on recent developments; (b) focus our collective understanding on determining key research gaps; and, to the extent possible, (c) develop a plan to communicate both advances and science gaps to wider audiences. Presentations and group discussions were framed mainly in the geographic context of the western US. The symposium addressed dual central themes—historical aspen cover change and ungulate herbivory—both of which have important ramifications for future aspen resilience. We also found emergent themes in disturbance, climate work, and genetic innovation. This paper presents a brief review of the state of aspen science and a synopsis of issues and needs identified at the symposium. Detailed treatments of topics mentioned here are found in accompanying articles of this volume. A key recommendation from researchers here is that there are many ‘‘aspen types’’ and novel, landscape- or aspen type-specific, approaches will be required to appropriately address this regional diversity. We further emphasize needed interdisciplinary work addressing changing climates, altered disturbance patterns, intensive herbivory, and human drivers of ecological change
Targeted modulation of tropoelastin structure and assembly
Tropoelastin,
as the monomer unit of elastin, assembles into elastic
fibers that impart strength and resilience to elastic tissues. Tropoelastin
is also widely used to manufacture versatile materials with specific
mechanical and biological properties. The assembly of tropoelastin
into elastic fibers or biomaterials is crucially influenced by key
submolecular regions and specific residues within these domains. In
this work, we identify the functional contributions of two rarely
occurring negatively charged residues, glutamate 345 in domain 19
and glutamate 414 in domain 21, in jointly maintaining the native
conformation of the tropoelastin hinge, bridge and foot regions. Alanine
substitution of E345 and/or E414 variably alters the positioning and
interactive accessibility of these regions, as illustrated by nanostructural
studies and detected by antibody and cell probes. These structural
changes are associated with a lower propensity for monomer coacervation,
cross-linking into morphologically and functionally atypical hydrogels,
and markedly impaired and abnormal elastic fiber formation. Our work
indicates the crucial significance of both E345 and E414 residues
in modulating specific local structure and higher-order assembly of
human tropoelastin
Leptin and smoking cessation: secondary analyses of a randomized controlled trial assessing physical activity as an aid for smoking cessation.
BACKGROUND: Smokers have a lower body weight compared to non-smokers. Smoking cessation is associated with weight gain in most cases. A hormonal mechanism of action might be implicated in weight variations related to smoking, and leptin might be implicated. We made secondary analyses of an RCT, with a hypothesis-free exploratory approach to study the dynamic of leptin following smoking cessation.
METHODS: We measured serum leptin levels among 271 sedentary smokers willing to quit who participated in a randomized controlled trial assessing a 9-week moderate-intensity physical activity intervention as an aid for smoking cessation. We adjusted leptin for body fat levels. We performed linear regressions to test for an association between leptin levels and the study group over time.
RESULTS: One year after smoking cessation, the mean serum leptin change was +3.23 mg/l (SD 4.89) in the control group and +1.25 mg/l (SD 4.86) in the intervention group (p of the difference < 0.05). When adjusted for body fat levels, leptin was higher in the control group than in the intervention group (p of the difference < 0.01). The mean weight gain was +2.91 (SD 6.66) Kg in the intervention and +3.33 (SD 4.47) Kg in the control groups, respectively (p not significant).
CONCLUSIONS: Serum leptin levels significantly increased after smoking cessation, in spite of substantial weight gain. The leptin dynamic might be different in chronic tobacco users who quit smoking, and physical activity might impact the dynamic of leptin in such a situation.
CLINICAL TRIAL REGISTRATION NUMBER: NCT00521391
Association of smoking and nicotine dependence with pre-diabetes in young and healthy adults.
INTRODUCTION: Several studies have shown an increased risk of type 2 diabetes among smokers. Therefore, the aim of this analysis was to assess the relationship between smoking, cumulative smoking exposure and nicotine dependence with pre-diabetes.
METHODS: We performed a cross-sectional analysis of healthy adults aged 25-41 in the Principality of Liechtenstein. Individuals with known diabetes, Body Mass Index (BMI) >35 kg/m² and prevalent cardiovascular disease were excluded. Smoking behaviour was assessed by self-report. Pre-diabetes was defined as glycosylated haemoglobin between 5.7% and 6.4%. Multivariable logistic regression models were done.
RESULTS: Of the 2142 participants (median age 37 years), 499 (23.3%) had pre-diabetes. There were 1,168 (55%) never smokers, 503 (23%) past smokers and 471 (22%) current smokers, with a prevalence of pre-diabetes of 21.2%, 20.9% and 31.2%, respectively (p <0.0001). In multivariable regression models, current smokers had an odds ratio (OR) of pre-diabetes of 1.82 (95% confidential interval (CI) 1.39; 2.38, p <0.0001). Individuals with a smoking exposure of <5, 5-10 and >10 pack-years had an OR (95% CI) for pre-diabetes of 1.34 (0.90; 2.00), 1.80 (1.07; 3.01) and 2.51 (1.80; 3.59) (p linear trend <0.0001) compared with never smokers. A Fagerström score of 2, 3-5 and >5 among current smokers was associated with an OR (95% CI) for pre-diabetes of 1.27 (0.89; 1.82), 2.15 (1.48; 3.13) and 3.35 (1.73; 6.48) (p linear trend <0.0001).
DISCUSSION: Smoking is strongly associated with pre-diabetes in young adults with a low burden of smoking exposure. Nicotine dependence could be a potential mechanism of this relationship
Global and regional effects of the photochemistry of CH_3O_2NO_2: evidence from ARCTAS
Using measurements from the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) experiment, we show that methyl peroxy nitrate (CH_3O_2NO_2) is present in concentrations of ~5–15 pptv in the springtime arctic upper troposphere. We investigate the regional and global effects of CH_3O_2NO_2 by including its chemistry in the GEOS-Chem 3-D global chemical transport model. We find that at temperatures below 240 K inclusion of CH_3O_2NO_2 chemistry results in decreases of up to ~20 % in NO_x, ~20 % in N_2O_5, ~5 % in HNO3, ~2 % in ozone, and increases in methyl hydrogen peroxide of up to ~14 %. Larger changes are observed in biomass burning plumes lofted to high altitude. Additionally, by sequestering NO_x at low temperatures, CH_3O_2NO_2 decreases the cycling of HO_2 to OH, resulting in a larger upper tropospheric HO_2 to OH ratio. These results may impact some estimates of lightning NO_x sources as well as help explain differences between models and measurements of upper tropospheric composition
A Method to Improve the Early Stages of the Robotic Process Automation Lifecycle
The robotic automation of processes is of much interest to
organizations. A common use case is to automate the repetitive manual
tasks (or processes) that are currently done by back-office staff
through some information system (IS). The lifecycle of any Robotic Process
Automation (RPA) project starts with the analysis of the process
to automate. This is a very time-consuming phase, which in practical
settings often relies on the study of process documentation. Such documentation
is typically incomplete or inaccurate, e.g., some documented
cases never occur, occurring cases are not documented, or documented
cases differ from reality. To deploy robots in a production environment
that are designed on such a shaky basis entails a high risk. This paper
describes and evaluates a new proposal for the early stages of an RPA
project: the analysis of a process and its subsequent design. The idea is to
leverage the knowledge of back-office staff, which starts by monitoring
them in a non-invasive manner. This is done through a screen-mousekey-
logger, i.e., a sequence of images, mouse actions, and key actions
are stored along with their timestamps. The log which is obtained in
this way is transformed into a UI log through image-analysis techniques
(e.g., fingerprinting or OCR) and then transformed into a process model
by the use of process discovery algorithms. We evaluated this method for
two real-life, industrial cases. The evaluation shows clear and substantial
benefits in terms of accuracy and speed. This paper presents the method,
along with a number of limitations that need to be addressed such that
it can be applied in wider contexts.Ministerio de Economía y Competitividad TIN2016-76956-C3-2-
Even Between-Lap Pacing Despite High Within-Lap Variation During Mountain Biking
Purpose: Given the paucity of research on pacing strategies during competitive events, this study examined
changes in dynamic high-resolution performance parameters to analyze pacing profiles during a multiple-lap
mountain-bike race over variable terrain. Methods: A global-positioning-system (GPS) unit (Garmin, Edge
305, USA) recorded velocity (m/s), distance (m), elevation (m), and heart rate at 1 Hz from 6 mountain-bike
riders (mean ± SD age = 27.2 ± 5.0 y, stature = 176.8 ± 8.1 cm, mass = 76.3 ± 11.7 kg, VO2max = 55.1 ± 6.0 mL
· kg–1 . min–1) competing in a multilap race. Lap-by-lap (interlap) pacing was analyzed using a 1-way ANOVA
for mean time and mean velocity. Velocity data were averaged every 100 m and plotted against race distance
and elevation to observe the presence of intralap variation. Results: There was no significant difference in lap times (P = .99) or lap velocity (P = .65) across the 5 laps. Within each lap, a high degree of oscillation in velocity was observed, which broadly reflected changes in terrain, but high-resolution data demonstrated additional
nonmonotonic variation not related to terrain. Conclusion: Participants adopted an even pace strategy across
the 5 laps despite rapid adjustments in velocity during each lap. While topographical and technical variations
of the course accounted for some of the variability in velocity, the additional rapid adjustments in velocity
may be associated with dynamic regulation of self-paced exercise
The promise of internationally collaborative research for studying occupation: the example of the older women's food preparation study
Growing awareness of the Western perspectives underpinning occupational science and occupational therapy’s values, theories, and evaluation tools has given rise to questions about culturally relevant knowledge and practice with non-Western populations. To make sense of attempts to develop cross-cultural knowledge taking place within the profession and discipline, the authors review epistemological perspectives and methodological advances in anthropology and psychology. Thus informed, they both summarize and critique constructivist and positivist approaches to knowledge development and practice that cross or resist the crossing of cultures. The authors outline a multicultural collaborative research method that supports extending and refining the profession’s knowledge in a way that both honors local perspectives and reveals concepts that cross cultures. Insights from a study that explored the meaning of food preparation to older Thai, American, and New Zealand women provide illustrative examples
Pattern Recognition for Nondestructive Evaluation
The issues involved in automating nondestructive evaluation (NDE) techniques are outlined. Attention is given to research focused on the application of machine learning techniques to the construction and maintenance of knowledge-based systems which are capable of evaluating the readings from nondestructive tests that have been performed on aircraft components. Preliminary results obtained from this research are described. In particular, the authors discuss the application of a symbolic machine learning algorithm, ID3, to the NDE problem. ID3 has been used by Douglas Aircraft to classify defects in sets of standard NDE reference blocks. Based on the preliminary results, a need for an improved method of distinguishing features in the test waveforms is identified. The authors also outline a feature extraction approach from pattern recognition, called scale-space filtering, which can be used to preprocess data for input into a classification algorithm such as ID3
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