998 research outputs found
The influence of temporal resolution on crop yield estimation with Earth Observation data assimilation
Crop growth simulation models are often used to estimate crop yield.For most models, this requires crop, water, and soil management information, though this information is often lacking in many regions of the world. Assimilation of Earth observation (EO) data in crop growth models can generate field-level yield estimates over large areas. The use of EO for assimilation often requires a trade-off between spatial and temporal resolution. Spatiotemporal data fusion can provide higher spatial (≤30m) and temporal resolution data to avoid this trade-off. In this study, we evaluated the timing and frequency of EO data assimilation in the Simple Algorithm for Yield Estimation (SAFY) in a persistently cloudy and fragmented agroecosystem of Ethiopia for 2019 and 2020 growing seasons. We used Landsat and MODIS data fusion to obtain frequent and spatially detailed LAI estimates and assimilated at each main maize growth stage to evaluate the effect of timing and frequency of LAI assimilation. The jointing to grain filling stage observations were more important (RMSE = 117 g/m2, rRMSE = 16%) than other growth stages to improve yield estimation. Using LAI estimates at key crop growth stages was more influential than the frequency of LAI estimates. Reasonably accurate yield estimation (rRMSE = 20%) was obtained using the pre-peak growth stage LAI observations, suggesting that the method is suitable for in-season yield forecasting. LAI retrieval errors from EO data, particularly at the early and late growth stages, were the source of yield estimation uncertainty. Therefore, assimilation of other EO-derived biophysical variables and improving LAI retrieval accuracy from EO data could further improve crop growth model performance in smallholder agricultural systems
External cadmium and internal calcium block of single calcium channels in smooth muscle cells from rabbit mesenteric artery
The patch clamp technique was used to record unitary currents through single calcium channels from smooth muscle cells of rabbit mesenteric arteries. The effects of external cadmium and cobalt and internal calcium, barium, cadmium, and magnesium on single channel currents were investigated with 80 mM barium as the charge carrier and Bay K 8644 to prolong openings. External cadmium shortened the mean open time of single Ca channels. Cadmium blocking and unblocking rate constants of 16.5 mM-1 ms-1 and 0.6 ms-1, respectively, were determined, corresponding to dissociation constant Kd of 36 microM at -20 mV. These results are very similar to those reported for cardiac muscle Ca channels (Lansman, J. B., P. Hess, and R. W. Tsien. 1986. J. Gen. Physiol. 88:321–347). In contrast, Cd2+ (01–10 mM), when applied to the internal surface of Ca channels in inside-out patches, did not affect the mean open time, mean unitary current, or the variance of the open channel current. Internal calcium induced a flickery block, with a Kd of 5.8 mM. Mean blocking and unblocking rate constants for calcium of 0.56 mM-1 ms-1 and 3.22 ms-1, respectively, were determined. Internal barium (8 mM) reduced the mean unitary current by 36%. We conclude that under our experimental conditions, the Ca channel is not symmetrical with respect to inorganic ion block and that intracellular calcium can modulate Ca channel currents via a low-affinity binding site
Hydrodynamics of Spatially Ordered Superfluids
We derive the hydrodynamic equations for the supersolid and superhexatic
phases of a neutral two-dimensional Bose fluid. We find, assuming that the
normal part of the fluid is clamped to an underlying substrate, that both
phases can sustain third-sound modes and that in the supersolid phase there are
additional modes due to the superfluid motion of point defects (vacancies and
interstitials).Comment: 24 pages of ReVTeX and 7 uuencoded figures. Submitted for publication
in Phys. Rev.
Language Learning, Recasts, and Interaction Involving AAC: Background and Potential for Intervention
For children with typical development, language is learned through everyday discursive interaction. Adults mediate child participation in such interactions through the deployment of a range of co-constructive strategies, including repeating, questioning, prompting, expanding, and reformulating the child’s utterances. Adult reformulations of child utterances, also known as recasts, have also been shown to relate to the acquisition of linguistic structures in children with language and learning disabilities and children and adults learning a foreign language. In this paper we discuss the theoretical basis and empirical evidence for the use of different types of recasts as a major language learning catalyst, and what may account for their facilitative effects. We consider the occurrence of different types of recasts in AAC-mediated interactions and their potential for language facilitation, within the typical operational and linguistic constraints of such interactions. We also consider the benefit of explicit and corrective forms of recasts for language facilitation in conversations with children who rely on AAC. We conclude by outlining future research directions
A Current Mode Detector Array for Gamma-Ray Asymmetry Measurements
We have built a CsI(Tl) gamma-ray detector array for the NPDGamma experiment
to search for a small parity-violating directional asymmetry in the angular
distribution of 2.2 MeV gamma-rays from the capture of polarized cold neutrons
by protons with a sensitivity of several ppb. The weak pion-nucleon coupling
constant can be determined from this asymmetry. The small size of the asymmetry
requires a high cold neutron flux, control of systematic errors at the ppb
level, and the use of current mode gamma-ray detection with vacuum photo diodes
and low-noise solid-state preamplifiers. The average detector photoelectron
yield was determined to be 1300 photoelectrons per MeV. The RMS width seen in
the measurement is therefore dominated by the fluctuations in the number of
gamma rays absorbed in the detector (counting statistics) rather than the
intrinsic detector noise. The detectors were tested for noise performance,
sensitivity to magnetic fields, pedestal stability and cosmic background. False
asymmetries due to gain changes and electronic pickup in the detector system
were measured to be consistent with zero to an accuracy of in a few
hours. We report on the design, operating criteria, and the results of
measurements performed to test the detector array.Comment: 33 pages, 20 figures, 2 table
Language learning, recasts, and interaction involving AAC: background and potential for intervention
Radiofrequency ablation of ventricular tachycardia in Anderson–Fabry disease : a case series
Background
Cardiac involvement in Anderson–Fabry disease (AFD) can lead to arrhythmia, including ventricular tachycardia (VT). The literature on radiofrequency ablation (RFA) for the treatment of VT in AFD disease is limited.
Case summary
We discuss RFA of drug-refractory VT electrical storm in three males with AFD. The first patient (53 years old) had extensive involvement of the inferolateral left ventricle (LV) demonstrated with cardiac magnetic resonance imaging (CMRI), with a left ventricular ejection fraction (LVEF) of 35%. Two VT ablation procedures were performed. At the first procedure, the inferobasal endocardial LV was ablated. Furthermore, VT prompted a second ablation, where epicardial and endocardial sites were ablated. The acute arrhythmia burden was controlled but he died 4 months later despite appropriate implantable cardioverter-defibrillator therapies for VT. The second patient (67 years old) had full-thickness inferolateral involvement demonstrated with CMRI and LVEF of 45%. RFA of several endocardial left ventricular sites was performed. Over a 3-year follow-up, only brief non-sustained VT was identified, but he subsequently died of cardiac failure. Our third patient (69 years old), had an LVEF of 35%. He had RFA of endocardial left ventricular apical disease, but died 3 weeks later of cardiac failure.
Discussion
RFA of drug-refractory VT in AFD is feasible using standard electrophysiological mapping and ablation techniques, although the added clinical benefit is of questionable value. VT storm in the context of AFD may be a marker of end-stage disease
Community structures of actively growing bacteria shift along a north-south transect in the western North Pacific
Bacterial community structures and their activities in the ocean are tightly coupled with organic matter fluxes and thus control ocean biogeochemical cycles. Bromodeoxyuridine (BrdU), halogenated nucleoside and thymidine analogue, has been recently used to monitor actively growing bacteria (AGB) in natural environments. We labelled DNA of proliferating cells in seawater bacterial assemblages with BrdU and determined community structures of the bacteria that were possible key species in mediating biochemical reactions in the ocean. Surface seawater samples were collected along a north-south transect in the North Pacific in October 2003 and subjected to BrdU magnetic beads immunocapture and PCR-DGGE (BUMP-DGGE) analysis. Change of BrdU-incorporated community structures reflected the change of water masses along a north-south transect from subarctic to subtropical gyres in the North Pacific. We identified 25 bands referred to AGB as BrdU-incorporated phylotypes, belonging to Alphaproteobacteria (5 bands), Betaproteobacteria (1 band), Gammaproteobacteria (4 bands), Cytophaga-Flavobacterium-Bacteroides (CFB) group bacteria (5 bands), Gram-positive bacteria (6 bands), and Cyanobacteria (4 bands). BrdU-incorporated phylotypes belonging to Vibrionales, Alteromonadales and Gram-positive bacteria appeared only at sampling stations in a subtropical gyre, while those belonging to Roseobacter-related bacteria and CFB group bacteria appeared at the stations in both subarctic and subtropical gyres. Our result revealed phylogenetic affiliation of AGB and their dynamic change along with north-south environmental gradients in open oceans. Different species of AGB utilize different amount and kinds of substrates, which can affect the change of organic matter fluxes along transect
Genome-wide meta-analysis identified novel variant associated with hallux valgus in Caucasians
Background: Hallux valgus, one of the most common structural foot deformities, is highly heritable. However, previous efforts to elucidate the genetic underpinnings of hallux valgus through a genome-wide association study (GWAS) conducted in 4409 Caucasians did not identify genome-wide significant associations with hallux valgus in both gender-specific and sex-combined GWAS meta-analyses. In this analysis, we add newly available data and more densely imputed genotypes to identify novel genetic variants associated with hallux valgus. Methods: A total of 5925 individuals of European Ancestry were categorized into two groups: 'hallux valgus present' (n = 2314) or 'no deformity' (n = 3611) as determined by trained examiners or using the Manchester grading scale. Genotyping was performed using commercially available arrays followed by imputation to the Haplotype Reference Consortium (HRC) reference panel version 1.1. We conducted both sex-specific and sex-combined association analyses using logistic regression and generalized estimating equations as appropriate in each cohort. Results were then combined in a fixed-effects inverse-variance meta-analyses. Functional Mapping and Annotation web-based platform (FUMA) was used for positional mapping, gene and gene-set analyses. Results: We identified a novel locus in the intronic region of CLCA2 on chromosome 1, rs55807512 (OR = 0.48, p = 2.96E-09), an expression quantitative trait locus for COL24A1, a member of the collagen gene family. Conclusion: In this report of the largest GWAS of hallux valgus to date, we identified a novel genome-wide significant locus for hallux valgus. Additional replication and functional follow-up will be needed to determine the functional role of this locus in hallux valgus biology
Joint hypermobility is not positively associated with prevalent multiple joint osteoarthritis: A cross-sectional study of older adults
Background: This cross-sectional study evaluated associations of joint hypermobility and multiple joint osteoarthritis (MJOA) in a community-based cohort of adults 45+ years of age. Methods: MJOA and joint hypermobility data were from 1677 participants (mean age 69 years, 68% women) who completed research clinic visits during 2003-2010. Prevalent MJOA was defined in four ways. Radiographic OA (rOA) was defined as Kellgren-Lawrence (KL) > 2 at any included study joint; symptomatic OA (sxOA) required both symptoms and rOA in a joint. Joint hypermobility was defined as a Beighton score of > 4. Separate logistic regression models were used to estimate odds ratios (OR) between joint hypermobility and each MJOA definition, adjusting for age, sex, race, body mass index, and baseline visit. Results: In this cohort, 4% had Beighton score > 4 and 63% met any definition of MJOA. Joint hypermobility was associated with significantly lower odds of radiographic and symptomatic MJOA-1 (multiple joint OA-definition 1: involvement of > 1 IP (interphalangeal) nodes and > 2 sites of hip, knee, and spine; 74 and 58% lower, respectively). However, for the other MJOA definitions (i.e., MJOA-2:involvement of > 2 IP joints, > 1 carpometacarpal [CMC] joints, and knee or hip sites; MJOA-3: involvement of > 5 joint sites from among distal interphalangeal, proximal interphalangeal, CMC, hip, knee, or spine sites; and MJOA-4:involvement of > 2 lower body sites (hip, knee, or spine), there were no statistically significant associations. For associations between site-specific hypermobility and any MJOA definition, most adjusted ORs were less than one, but few were statistically significant. Conclusions: Overall, joint hypermobility was not positively associated with any definition of prevalent MJOA in this cohort, and an inverse association existed with one definition of MJOA. Longitudinal studies are needed to determine the contribution of hypermobility to the incidence and progression of MJOA outcomes
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