1,190 research outputs found
Relationship of crop metabolism and water status to irrigation need
Irrigation represents the largest segment of consumptive water use in the U.S. Consequently, improvements in the efficiency of irrigation can have an important effect on the amount of water available for other uses. This research was initiated to determine the physiological limitations to crop yield during drought. The identification of these parameters may provide a way of estimating plant need for irrigation and avoiding unnecessary applications of water. Maize was grown to maturity, and photosynthesis and translocation of photosynthates were studied when drought occurred during grain development. Both carbon-14 labeling of the photosynthetic products and dry weight determinations indicated that net photosynthesis was substantially reduced whereas translocation was relatively rapid during drought. Furthermore, grain production occurred in proportion to the cumulative photosynthesis for the season. It was concluded that photosynthesis was more limiting than translocation to grain fill under dry conditions and that photosynthetic behavior could be used to reflect the need of maize crops for water.U.S. Geological SurveyU.S. Department of the InteriorOpe
Psychometric Analysis of the Heart Failure Somatic Perception Scale as a Measure of Patient Symptom Perception.
BACKGROUND: Symptoms are known to predict survival among patients with heart failure (HF), but discrepancies exist between patients\u27 and health providers\u27 perceptions of HF symptom burden.
OBJECTIVE: The purpose of this study is to quantify the internal consistency, validity, and prognostic value of patient perception of a broad range of HF symptoms using an HF-specific physical symptom measure, the 18-item HF Somatic Perception Scale v. 3.
METHODS: Factor analysis of the HF Somatic Perception Scale was conducted in a convenience sample of 378 patients with chronic HF. Convergent validity was examined using the Physical Limitation subscale of the Kansas City Cardiomyopathy Questionnaire. Divergent validity was examined using the Self-care of HF Index self-care management score. One-year survival based on HF Somatic Perception Scale scores was quantified using Cox regression controlling for Seattle HF Model scores to account for clinical status, therapeutics, and lab values.
RESULTS: The sample was 63% male, 85% white, 67% functionally compromised (New York Heart Association class III-IV) with a mean (SD) age of 63 (12.8) years. Internal consistency of the HF Somatic Perception Scale was α = .90. Convergent (r = -0.54, P \u3c .0001) and divergent (r = 0.18, P \u3e .05) validities were supported. Controlling for Seattle HF scores, HF Somatic Perception Scale was a significant predictor of 1-year survival, with those most symptomatic having worse survival (hazard ratio, 1.012; 95% confidence interval, 1.001-1.024; P = .038).
CONCLUSIONS: Perception of HF symptom burden as measured by the HF Somatic Perception Scale is a significant predictor of survival, contributing additional prognostic value over and above objective Seattle HF Risk Model scores. This analysis suggests that assessment of a broad range of HF symptoms, or those related to dyspnea or early and subtle symptoms, may be useful in evaluating therapeutic outcomes and predicting event-free survival
Why We Read Wikipedia
Wikipedia is one of the most popular sites on the Web, with millions of users
relying on it to satisfy a broad range of information needs every day. Although
it is crucial to understand what exactly these needs are in order to be able to
meet them, little is currently known about why users visit Wikipedia. The goal
of this paper is to fill this gap by combining a survey of Wikipedia readers
with a log-based analysis of user activity. Based on an initial series of user
surveys, we build a taxonomy of Wikipedia use cases along several dimensions,
capturing users' motivations to visit Wikipedia, the depth of knowledge they
are seeking, and their knowledge of the topic of interest prior to visiting
Wikipedia. Then, we quantify the prevalence of these use cases via a
large-scale user survey conducted on live Wikipedia with almost 30,000
responses. Our analyses highlight the variety of factors driving users to
Wikipedia, such as current events, media coverage of a topic, personal
curiosity, work or school assignments, or boredom. Finally, we match survey
responses to the respondents' digital traces in Wikipedia's server logs,
enabling the discovery of behavioral patterns associated with specific use
cases. For instance, we observe long and fast-paced page sequences across
topics for users who are bored or exploring randomly, whereas those using
Wikipedia for work or school spend more time on individual articles focused on
topics such as science. Our findings advance our understanding of reader
motivations and behavior on Wikipedia and can have implications for developers
aiming to improve Wikipedia's user experience, editors striving to cater to
their readers' needs, third-party services (such as search engines) providing
access to Wikipedia content, and researchers aiming to build tools such as
recommendation engines.Comment: Published in WWW'17; v2 fixes caption of Table
Опухоль брюшной стенки - грыжа спигелевой линии, содержащая метастатическую карциному с невыявленным первичным очагом
АДЕНОКАРЦИНОМАБРЮШНАЯ СТЕНКАГРЫЖИКАРЦИНОМАКОЛОРЕКТАЛЬНЫЕ НОВООБРАЗОВАНИЯНОВООБРАЗОВАНИЯТОЛСТАЯ КИШК
Vascular signalling mediated by ZWILLE potentiates WUSCHEL function during shoot meristem stem cell development in the Arabidopsis embryo
Stem cells are maintained in an undifferentiated state by signals from their microenvironment, the stem cell niche. Despite its central role for organogenesis throughout the plant's life, little is known about how niche development is regulated in the Arabidopsis embryo. Here we show that, in the absence of functional ZWILLE (ZLL), which is a member of the ARGONAUTE (AGO) family, stem cell-specific expression of the signal peptide gene CLAVATA3 (CLV3) is not maintained despite increased levels of the homeodomain transcription factor WUSCHEL (WUS), which is expressed in the organising centre (OC) of the niche and normally promotes stem cell identity. Tissue-specific expression indicates that ZLL acts to maintain the stem cells from the neighbouring vascular primordium, providing direct evidence for a non-cell-autonomous mechanism. Furthermore, mutant and marker gene analyses suggest that during shoot meristem formation, ZLL functions in a similar manner but in a sequential order with its close homologue AGO1, which mediates RNA interference. Thus, WUS-dependent OC signalling to the stem cells is promoted by AGO1 and subsequently maintained by a provascular ZLL-dependent signalling pathway.Matthew R. Tucker, Annika Hinze, Elise J. Tucker, Shinobu Takada, Gerd Jürgens and Thomas Lau
Asynchronous Training of Word Embeddings for Large Text Corpora
Word embeddings are a powerful approach for analyzing language and have been
widely popular in numerous tasks in information retrieval and text mining.
Training embeddings over huge corpora is computationally expensive because the
input is typically sequentially processed and parameters are synchronously
updated. Distributed architectures for asynchronous training that have been
proposed either focus on scaling vocabulary sizes and dimensionality or suffer
from expensive synchronization latencies.
In this paper, we propose a scalable approach to train word embeddings by
partitioning the input space instead in order to scale to massive text corpora
while not sacrificing the performance of the embeddings. Our training procedure
does not involve any parameter synchronization except a final sub-model merge
phase that typically executes in a few minutes. Our distributed training scales
seamlessly to large corpus sizes and we get comparable and sometimes even up to
45% performance improvement in a variety of NLP benchmarks using models trained
by our distributed procedure which requires of the time taken by the
baseline approach. Finally we also show that we are robust to missing words in
sub-models and are able to effectively reconstruct word representations.Comment: This paper contains 9 pages and has been accepted in the WSDM201
Motivational Interviewing to Improve Self-Care for Patients with Chronic Heart Failure: MITI-HF Randomized Controlled Trial
OBJECTIVE: The purpose of this study was to test the efficacy of a tailored motivational interviewing (MI) intervention versus usual care for improving HF self-care behaviors, physical HF symptoms and quality of life.
METHODS: This is a single-center, randomized controlled trial. Participants were enrolled in the hospital. Immediately after discharge, those in the intervention group received a single home visit and 3-4 follow-up phone calls by a nurse over 90 days.
RESULTS: A total of 67 participants completed the study (mean age 62±12.8 years), of which 54% were African American, 30% were female, 84% had class III/IV symptoms, and 63% were educated at a high school level or less. There were no differences between the groups in self-care maintenance, self-care confidence, physical HF symptoms, or quality of life at 90 days.
CONCLUSION: Patients who received the MI intervention had significant and clinically meaningful improvements in HF self-care maintenance over 90 days that exceeded that of usual care.
PRACTICE IMPLICATIONS: These data support the use of a nurse-led MI intervention for improving HF self-care. Identifying methods to improve HF self-care may lead to improved clinical outcomes
Communication calls produced by electrical stimulation of four structures in the guinea pig brain
One of the main central processes affecting the cortical representation of conspecific vocalizations is the collateral output from the extended motor system for call generation. Before starting to study this interaction we sought to compare the characteristics of calls produced by stimulating four different parts of the brain in guinea pigs (Cavia porcellus). By using anaesthetised animals we were able to reposition electrodes without distressing the animals. Trains of 100 electrical pulses were used to stimulate the midbrain periaqueductal grey (PAG), hypothalamus, amygdala, and anterior cingulate cortex (ACC). Each structure produced a similar range of calls, but in significantly different proportions. Two of the spontaneous calls (chirrup and purr) were never produced by electrical stimulation and although we identified versions of chutter, durr and tooth chatter, they differed significantly from our natural call templates. However, we were routinely able to elicit seven other identifiable calls. All seven calls were produced both during the 1.6 s period of stimulation and subsequently in a period which could last for more than a minute. A single stimulation site could produce four or five different calls, but the amygdala was much less likely to produce a scream, whistle or rising whistle than any of the other structures. These three high-frequency calls were more likely to be produced by females than males. There were also differences in the timing of the call production with the amygdala primarily producing calls during the electrical stimulation and the hypothalamus mainly producing calls after the electrical stimulation. For all four structures a significantly higher stimulation current was required in males than females. We conclude that all four structures can be stimulated to produce fictive vocalizations that should be useful in studying the relationship between the vocal motor system and cortical sensory representation
Domain-independent Extraction of Scientific Concepts from Research Articles
We examine the novel task of domain-independent scientific concept extraction
from abstracts of scholarly articles and present two contributions. First, we
suggest a set of generic scientific concepts that have been identified in a
systematic annotation process. This set of concepts is utilised to annotate a
corpus of scientific abstracts from 10 domains of Science, Technology and
Medicine at the phrasal level in a joint effort with domain experts. The
resulting dataset is used in a set of benchmark experiments to (a) provide
baseline performance for this task, (b) examine the transferability of concepts
between domains. Second, we present two deep learning systems as baselines. In
particular, we propose active learning to deal with different domains in our
task. The experimental results show that (1) a substantial agreement is
achievable by non-experts after consultation with domain experts, (2) the
baseline system achieves a fairly high F1 score, (3) active learning enables us
to nearly halve the amount of required training data.Comment: Accepted for publishing in 42nd European Conference on IR Research,
ECIR 202
Heart Failure Symptom Biology in Response to Ventricular Assist Device Implantation.
BACKGROUND: We have a limited understanding of the biological underpinnings of symptoms in heart failure (HF), particularly in response to left ventricular assist device (LVAD) implantation.
OBJECTIVE: The aim of this study was to quantify the degree to which symptoms and biomarkers change in parallel from before implantation through the first 6 months after LVAD implantation in advanced HF.
METHODS: This was a prospective cohort study of 101 patients receiving an LVAD for the management of advanced HF. Data on symptoms (dyspnea, early and subtle symptoms [HF Somatic Perception Scale], pain severity [Brief Pain Inventory], wake disturbance [Epworth Sleepiness Scale], depression [Patient Health Questionnaire], and anxiety [Brief Symptom Inventory]) and peripheral biomarkers of myocardial stretch, systemic inflammation, and hypervolumetric mechanical stress were measured before implantation with a commercially available LVAD and again at 30, 90, and 180 days after LVAD implantation. Latent growth curve and parallel process modeling were used to describe changes in symptoms and biomarkers and the degree to which they change in parallel in response to LVAD implantation.
RESULTS: In response to LVAD implantation, changes in myocardial stretch were closely associated with changes in early and subtle physical symptoms as well as depression, and changes in hypervolumetric stress were closely associated with changes in pain severity and wake disturbances. Changes in systemic inflammation were not closely associated with changes in physical or affective symptoms in response to LVAD implantation.
CONCLUSIONS: These findings provide new insights into the many ways in which symptoms and biomarkers provide concordant or discordant information about LVAD response
- …