563 research outputs found
Accurate and robust image superresolution by neural processing of local image representations
Image superresolution involves the processing of an image sequence to generate a still image with higher resolution. Classical approaches, such as bayesian MAP methods, require iterative minimization procedures, with high computational costs. Recently, the authors proposed a method to tackle this problem, based on the use of a hybrid MLP-PNN architecture. In this paper, we present a novel superresolution method, based on an evolution of this concept, to incorporate the use of local image models. A neural processing stage receives as input the value of model coefficients on local windows. The data dimension-ality is firstly reduced by application of PCA. An MLP, trained on synthetic se-quences with various amounts of noise, estimates the high-resolution image data. The effect of varying the dimension of the network input space is exam-ined, showing a complex, structured behavior. Quantitative results are presented showing the accuracy and robustness of the proposed method
Biomass, carbon and nitrogen dynamics of multi-species riparian buffers within an agricultural watershed in Iowa,USA
This study was conducted to determine biomass dynamics, carbon sequestration and plant nitrogen immobiliza- tion in multispecies riparian buffers, cool-season grass buffers and adjacent crop ?elds in central Iowa. The seven-year-old multispecies buffers were composed of poplar (Populus × euroamericana ‘Eugenei’) and switch- grass (Panicum virgatum L.). The cool-season grass buffers were dominated by non-native forage grasses (Bro- mus inermis Leysser., Phleum pratense L. and Poa pratensis L). Crop ?elds were under an annual corn-soybean rotation. Aboveground non-woody live and dead biomass were determined by direct harvests throughout two growing seasons. The dynamics of ?ne (0–2 mm) and small roots (2–5 mm) were assessed by sequentially col- lecting 35 cm deep, 5.4 cm diameter cores (125 cm deep cores in the second year) from April through Novem- ber. Biomass of poplar trees was estimated using allometric equations developed by destructive sampling of trees. Poplar had the greatest aboveground live biomass, N and C pools, while switchgrass had the highest mean aboveground dead biomass, C and N pools. Over the two-year sampling period, live ?ne root biomass and root C and N in the riparian buffers were signi?cantly greater than in crop ?elds. Growing-season mean biomass, C and N pools were greater in the multispecies buffer than in either of the crop ?elds or cool-season grass buffers. Rates of C accumulation in plant and litter biomass in the planted poplar and switchgrass stands averaged 2960 and 820 kg C ha-1 y-1, respectively. Nitrogen immobilization rates in the poplar stands and switchgrass sites averaged 37 and 16 kg N ha-1 y-1, respectively. Planted riparian buffers containing native perennial species therefore have the potential to sequester C from the atmosphere, and to immobilize N in biomass, therefore slow- ing or preventing N losses to the atmosphere and to ground and surface waters
Soil respiration within riparian buffers and adjacent crop fields
3 We quantified rates of soil respiration among sites within an agricultural 4 landscape in central Iowa, USA. The study was conducted in riparian cool-season grass 5 buffers, in re-established multispecies (switchgrass + poplar) riparian buffers and in 6 adjacent crop (maize and soybean) fields. The objectives were to determine the 7 variability in soil respiration among buffer types and crop fields within a riparian 8 landscape, and to identify those factors correlating with the observed differences. Soil 9 respiration was measured approximately monthly over a two-year period using the soda- 10 lime technique. Mean daily soil respiration across all treatments ranged from 0.14-8.3 g 11 C m-2 d-1. There were no significant differences between cool-season grass buffers and 12 re-established forest buffers, but respiration rates beneath switchgrass were significantly 13 lower than those beneath cool-season grass. Soil respiration was significantly greater in 14 both buffer systems than in the cropped fields. Seasonal changes in soil respiration were 15 strongly related to temperature changes. Over all sites, soil temperature and soil moisture 16 together accounted for 69 % of the seasonal variability in soil respiration. Annual soil 17 respiration rates correlated strongly with soil organic carbon (R =0.75, P<0.001) and fine 18 root (<2 mm) biomass (R=0.85, P<0.001). Annual soil respiration rates averaged 1140 C 19 m-2 for poplar, 1185 g C m-2 for cool-season grass, 1020 g C m-2 for switchgrass, 750 g 20 C m-2 for soybean and 740 g C m-2 for corn. Overall, vegetated buffers had significantly 21 higher soil respiration rates than did adjacent crop fields, indicating greater soil biological 22 activity within the buffers
Coruh river dam projects and their ecological impacts
Coruh river starts from Mescit Mountains of Bayburt, Turkey and reaches Black Sea in Batum, Georgia. The total length of the river is around 431 km. and 410 km of it in the boundries of Turkey and the remaining 21 km in the Georgia. The annual discharge of the river is 6.3 billion cubic meter. Coruh is the fastest running river of the Turkey with an elevational difference of 1420 m. It carries 5.8 million cubic meter of sediment each year. Ten dams are planned to construct on the main river while 21 planned to construct on the branches of the river. They will generate 10.6 billions kWh energy per year. Seven of these dams are located in the vicinity of Artvin. Construction of new roads have also started to solve the transportation problem of the area because some part of the roads are going to be covered by the water. Road construction will damage the forests of the valley due to high slope in the area. Fish species living in the river such as Salmo trutta labrax, Salmo trutta lcapius, Cypirinus carpio, Barbus cycloepsis and Silurus glanis are going to lose their habitat. The region is rich in endemism. The number of endemic species is 119 for Artvin and some of them grows in the main valley of Coruh river. They will lose their habitat after the construction of the dams
Genomic exploration of sequential clinical isolates reveals a distinctive molecular signature of persistent Staphylococcus aureus bacteraemia.
Large-scale genomic studies of within-host diversity in Staphylococcus aureus bacteraemia (SAB) are needed to understanding bacterial adaptation underlying persistence and thus refining the role of genomics in management of SAB. However, available comparative genomic studies of sequential SAB isolates have tended to focus on selected cases of unusually prolonged bacteraemia, where secondary antimicrobial resistance has developed.
To understand bacterial genetic diversity during SAB more broadly, we applied whole genome sequencing to a large collection of sequential isolates obtained from patients with persistent or relapsing bacteraemia. After excluding genetically unrelated isolates, we performed an in-depth genomic analysis of point mutations and chromosome structural variants arising within individual SAB episodes.
We show that, while adaptation pathways are heterogenous and episode-specific, isolates from persistent bacteraemia have a distinctive molecular signature, characterised by a low mutation frequency and high proportion of non-silent mutations. Analysis of structural genomic variants revealed that these often overlooked genetic events are commonly acquired during SAB. We discovered that IS256 insertion may represent the most effective driver of within-host microevolution in selected lineages, with up to three new insertion events per isolate even in the absence of other mutations. Genetic mechanisms resulting in significant phenotypic changes, such as increases in vancomycin resistance, development of small colony phenotypes, and decreases in cytotoxicity, included mutations in key genes (rpoB, stp, agrA) and an IS256 insertion upstream of the walKR operon.
This study provides for the first time a large-scale analysis of within-host genomic changes during invasive S. aureus infection and describes specific patterns of adaptation that will be informative for both understanding S. aureus pathoadaptation and utilising genomics for management of complicated S. aureus infections
Methane Flux in Cropland and Adjacent Riparian Buff ers with Different Vegetation Covers
While water quality functions of conservation buffers established adjacent to cropped fields have been widely documented, the relative contribution of these re-established perennial plant systems to greenhouse gases has not been completely documented. In the case of methane (CH(4)), these systems have the potential to serve as sinks of CH(4) or may provide favorable conditions for CH(4) production. This study quantifies CH(4) flux from soils of riparian buffer systems comprised of three vegetation types and compares these fluxes with those of adjacent crop fields. We measured soil properties and diel and seasonal variations of CH(4) flux in 7 to 17 yr-old re-established riparian forest buffers, warm-season and cool-season grass filters, and an adjacent crop field located in the Bear Creek watershed in central Iowa. Forest buffer and grass filter soils had significantly lower bulk density (P \u3c 0.01); and higher pH (P \u3c 0.01), total carbon (TC) (P \u3c 0.01), and total nitrogen (TN) (P \u3c 0.01) than crop field soils. There was no significant relationship between CH(4) flux and soil moisture or soil temperature among sites within the range of conditions observed. Cumulative CH(4) flux was -0.80 kg CH(4)-C ha(-1) yr(-1) in the cropped field, -0.46 kg CH(4)-C ha(-1) yr(-1) within the forest buffers, and 0.04 kg CH(4)-C ha(-1) yr(-1) within grass filters, but difference among vegetation covers was not significant. Results suggest that CH(4) flux was not changed after establishment of perennial vegetation on cropped soils, despite significant changes in soil properties
A Novel Method for High-Dimensional Anatomical Mapping of Extra-Axial Cerebrospinal Fluid: Application to the Infant Brain
Cerebrospinal fluid (CSF) plays an essential role in early postnatal brain development. Extra-axial CSF (EA-CSF) volume, which is characterized by CSF in the subarachnoid space surrounding the brain, is a promising marker in the early detection of young children at risk for neurodevelopmental disorders. Previous studies have focused on global EA-CSF volume across the entire dorsal extent of the brain, and not regionally-specific EA-CSF measurements, because no tools were previously available for extracting local EA-CSF measures suitable for localized cortical surface analysis. In this paper, we propose a novel framework for the localized, cortical surface-based analysis of EA-CSF. The proposed processing framework combines probabilistic brain tissue segmentation, cortical surface reconstruction, and streamline-based local EA-CSF quantification. The quantitative analysis of local EA-CSF was applied to a dataset of typically developing infants with longitudinal MRI scans from 6 to 24 months of age. There was a high degree of consistency in the spatial patterns of local EA-CSF across age using the proposed methods. Statistical analysis of local EA-CSF revealed several novel findings: several regions of the cerebral cortex showed reductions in EA-CSF from 6 to 24 months of age, and specific regions showed higher local EA-CSF in males compared to females. These age-, sex-, and anatomically-specific patterns of local EA-CSF would not have been observed if only a global EA-CSF measure were utilized. The proposed methods are integrated into a freely available, open-source, cross-platform, user-friendly software tool, allowing neuroimaging labs to quantify local extra-axial CSF in their neuroimaging studies to investigate its role in typical and atypical brain development
Point-contact spectroscopy of the nickel borocarbide superconductor YNi2B2C in the normal and superconducting state
Point-contact (PC) spectroscopy measurements of YNi2B2C single crystals in
the normal and superconducting (SC) state (T_c=15.4K) for the main
crystallographic directions are reported. The PC study reveals the
electron-phonon interaction (EPI) spectral function with dominant phonon
maximum around 12 meV and further weak structures (hump or kink) at higher
energy at about 50 meV. No "soft" modes below 12 meV are resolved in the normal
state. The PC EPI spectra are qualitatively similar for the different
directions. Contrary, directional study of the SC gap results in
\Delta_[100]=1.5 meV for the a direction and \Delta_[001]=2.3 meV along the c
axis; however the critical temperature T_c in PC in all cases is near to that
in the bulk sample. The value 2\Delta_[001]/kT_c=3.6 is close to the BCS value
of 3.52, and the temperature dependence \Delta_[001](T) is BCS-like, while the
for small gap \Delta_[100](T) is below BCS behavior at T>T_c/2 similarly as in
the two-gap superconductor MgB2. It is supposed that the directional variation
\Delta can be attributed to a multiband nature of the SC state in YNi2B2C.Comment: 9 pages, 10 figures, to be published in a special issue of J. Low
Temp. Phys. in honour of Prof. H. von Loehneyse
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