1,481 research outputs found
Loci Controlling Resistance to High Plains Virus and Wheat Streak Mosaic Virus in a B73 × Mo17 Population of Maize
High Plains disease has the potential to cause significant yield loss in susceptible corn (Zea mays L.) and wheat (Triticum aestivum L.) genotypes, especially in the central and western USA. The primary causal agent, High Plains virus (HPV), is vectored by wheat curl mite (WCM; Aceria tossicheila Keifer), which is also the vector of wheat streak mosaic virus (WSMV). In general, the two diseases occur together as a mixed infection in the field. The objective of this research was to characterize the inheritance of HPV and WSMV resistance using B73 (resistant to HPV and WSMV) × Mo17 (moderately susceptible to HPV and WSMV) recombinant inbred lines. A population of 129 recombinant inbred lines scored for 167 molecular markers was used to evaluate resistance to WSMV and to a mixed infection of WSMV and HPV. Loci conferring resistance to systemic movement of WSMV in plants mapped to chromosomes 3, 6, and 10, consistent with the map position of wsm2, wsm1, and wsm3, respectively. Major genes for resistance to systemic spread of HPV in doubly infected plants mapped to chromosomes 3 and 6, coincident or tightly linked with the WSMV resistance loci. Analysis of doubly infected plants revealed that chromosome 6 had a major effect on HPV resistance, consistent with our previous analysis of B73 × W64A and B73 × Wf9 populations. Quantitative trait loci (QTL) affecting resistance to localized symptom development mapped to chromosomes 4 (umc66), 5 (bnl5.40), and 6 (umc85), and accounted for 24% of the phenotypic variation. Localized symptoms may reflect the amount of mite feeding or the extent of virus spread at the point of infection. Identification of cosegregating markers may facilitate selection for HPV and WSMV resistance in corn breeding programs
Using debris disk observations to infer substellar companions orbiting within or outside a parent planetesimal belt
Aims. We analyze whether the effects of secular perturbations, originating
from a substellar companion, on the dust dynamics in a debris disk can be
investigated with spatially resolved observations.
Methods. We numerically simulated the collisional evolution of narrow and
eccentric cold planetesimal belts around a star of spectral type A3V that are
secularly perturbed by a companion that orbits either closer to or farther from
the star than the belt. Based on the resulting spatial dust distributions, we
simulated spatially resolved maps of their surface brightness in the , ,
and bands and at wavelengths of 70m and 1300m.
Results. Assuming a nearby debris disk seen face-on, we find that the
brightness distribution varies significantly with observing wavelength, for
example between the and band. This can be explained by the varying
relative contribution of the emission of the smallest grains near the blowout
limit. The orbits of both the small grains that form the halo and the large
grains close to the parent belt precess due to the secular perturbations
induced by a companion orbiting inward of the belt. The halo, being composed of
older grains, trails the belt. The magnitude of the trailing decreases with
increasing perturber mass and hence with increasing strength of the
perturbation, a trend we recovered in synthetic maps of surface brightness by
fitting ellipses to lines of constant brightness. Systems with an outer
perturber do not show a uniform halo precession since the orbits of small
grains are strongly altered. We identified features of the brightness
distributions suitable for distinguishing between systems with a potentially
detectable inner or outer perturber, especially with a combined observation
with JWST/MIRI in the band tracing small grain emission and with ALMA at mm
wavelengths tracing the position of the parent planetesimal belt.Comment: Accepted for publication in Astronomy & Astrophysics. 25 pages, 21
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Ultra-high-resolution 3D imaging of atherosclerosis in mice with synchrotron differential phase contrast: a proof of concept study.
The goal of this study was to investigate the performance of 3D synchrotron differential phase contrast (DPC) imaging for the visualization of both macroscopic and microscopic aspects of atherosclerosis in the mouse vasculature ex vivo. The hearts and aortas of 2 atherosclerotic and 2 wild-type control mice were scanned with DPC imaging with an isotropic resolution of 15 μm. The coronary artery vessel walls were segmented in the DPC datasets to assess their thickness, and histological staining was performed at the level of atherosclerotic plaques. The DPC imaging allowed for the visualization of complex structures such as the coronary arteries and their branches, the thin fibrous cap of atherosclerotic plaques as well as the chordae tendineae. The coronary vessel wall thickness ranged from 37.4 ± 5.6 μm in proximal coronary arteries to 13.6 ± 3.3 μm in distal branches. No consistent differences in coronary vessel wall thickness were detected between the wild-type and atherosclerotic hearts in this proof-of-concept study, although the standard deviation in the atherosclerotic mice was higher in most segments, consistent with the observation of occasional focal vessel wall thickening. Overall, DPC imaging of the cardiovascular system of the mice allowed for a simultaneous detailed 3D morphological assessment of both large structures and microscopic details
Robust volume-targeted balanced steady-state free-precession coronary magnetic resonance angiography in a breathhold at 3.0 Tesla: a reproducibility study.
BACKGROUND: Transient balanced steady-state free-precession (bSSFP) has shown substantial promise for noninvasive assessment of coronary arteries but its utilization at 3.0 T and above has been hampered by susceptibility to field inhomogeneities that degrade image quality. The purpose of this work was to refine, implement, and test a robust, practical single-breathhold bSSFP coronary MRA sequence at 3.0 T and to test the reproducibility of the technique.
METHODS: A 3D, volume-targeted, high-resolution bSSFP sequence was implemented. Localized image-based shimming was performed to minimize inhomogeneities of both the static magnetic field and the radio frequency excitation field. Fifteen healthy volunteers and three patients with coronary artery disease underwent examination with the bSSFP sequence (scan time = 20.5 ± 2.0 seconds), and acquisitions were repeated in nine subjects. The images were quantitatively analyzed using a semi-automated software tool, and the repeatability and reproducibility of measurements were determined using regression analysis and intra-class correlation coefficient (ICC), in a blinded manner.
RESULTS: The 3D bSSFP sequence provided uniform, high-quality depiction of coronary arteries (n = 20). The average visible vessel length of 100.5 ± 6.3 mm and sharpness of 55 ± 2% compared favorably with earlier reported navigator-gated bSSFP and gradient echo sequences at 3.0 T. Length measurements demonstrated a highly statistically significant degree of inter-observer (r = 0.994, ICC = 0.993), intra-observer (r = 0.894, ICC = 0.896), and inter-scan concordance (r = 0.980, ICC = 0.974). Furthermore, ICC values demonstrated excellent intra-observer, inter-observer, and inter-scan agreement for vessel diameter measurements (ICC = 0.987, 0.976, and 0.961, respectively), and vessel sharpness values (ICC = 0.989, 0.938, and 0.904, respectively).
CONCLUSIONS: The 3D bSSFP acquisition, using a state-of-the-art MR scanner equipped with recently available technologies such as multi-transmit, 32-channel cardiac coil, and localized B0 and B1+ shimming, allows accelerated and reproducible multi-segment assessment of the major coronary arteries at 3.0 T in a single breathhold. This rapid sequence may be especially useful for functional imaging of the coronaries where the acquisition time is limited by the stress duration and in cases where low navigator-gating efficiency prohibits acquisition of a free breathing scan in a reasonable time period
Breast abscess due to Actinomyces europaeus
Actinomyces europaeus was first described in 1997 as a new species causing predominantly skin and soft-tissue infections. Mastitis due to A. europaeus is an unusual condition. This article reports a case of primary breast abscess caused by A. europaeus in a postmenopausal woma
Exploring within-person variability in qualitative negative and positive Emotional Granularity by means of Latent Markov Factor Analysis
Emotional granularity (EG) is an individual’s ability to describe their emotional experiences in a nuanced and specific way. In this paper, we propose that researchers adopt latent Markov factor analysis (LMFA) to investigate within-person variability in qualitative EG (i.e., variability in distinct granularity patterns between specific emotions across time). LMFA clusters measurement occasions into latent states according to state-specific measurement models. We argue that state-specific measurement models of repeatedly assessed emotion items can provide information about qualitative EG at a given point in time. Applying LMFA to the area of EG for negative and positive emotions separately by using data from an experience sampling study with 11,662 measurement occasions across 139 participants, we found three latent EG states for the negative emotions and three for the positive emotions. Momentary stress significantly predicted transitions between the EG states for both the negative and positive emotions. We further identified two and three latent classes of individuals who differed in state trajectories for negative and positive emotions, respectively. Neuroticism and dispositional mood regulation predicted latent class membership for negative (but not for positive) emotions. We conclude that LMFA may enrich EG research by enabling more fine-grained insights into variability in qualitative EG patterns
Cytotoxic drug sensitivity of Epstein-Barr virus transformed lymphoblastoid B-cells.
BACKGROUND: Epstein-Barr virus (EBV) is the causative agent of immunosuppression
associated lymphoproliferations such as post-transplant lymphoproliferative
disorder (PTLD), AIDS related immunoblastic lymphomas (ARL) and immunoblastic
lymphomas in X-linked lymphoproliferative syndrome (XLP). The reported overall
mortality for PTLD often exceeds 50%. Reducing the immunosuppression in
recipients of solid organ transplants (SOT) or using highly active antiretroviral
therapy in AIDS patients leads to complete remission in 23-50% of the PTLD/ARL
cases but will not suffice for recipients of bone marrow grafts. An additional
therapeutic alternative is the treatment with anti-CD20 antibodies (Rituximab) or
EBV-specific cytotoxic T-cells. Chemotherapy is used for the non-responding cases
only as the second or third line of treatment. The most frequently used
chemotherapy regimens originate from the non-Hodgkin lymphoma protocols and there
are no cytotoxic drugs that have been specifically selected against EBV induced
lymphoproliferative disorders. METHODS: As lymphoblastoid cell lines (LCLs) are
well established in vitro models for PTLD, we have assessed 17 LCLs for cytotoxic
drug sensitivity. After three days of incubation, live and dead cells were
differentially stained using fluorescent dyes. The precise numbers of live and
dead cells were determined using a custom designed automated laser confocal
fluorescent microscope. RESULTS: Independently of their origin, LCLs showed very
similar drug sensitivity patterns against 29 frequently used cytostatic drugs.
LCLs were highly sensitive for vincristine, methotrexate, epirubicin and
paclitaxel. CONCLUSION: Our data shows that the inclusion of epirubicin and
paclitaxel into chemotherapy protocols against PTLD may be justified
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