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As part of the US Environmental Protection Agency's perfluoroalkyl and polyfluoroalkyl substances (PFAS) Action Plan, the agency is committed to increasing our understanding of the potential ecological effects of PFAS. The objective of these studies was to examine the developmental toxicity of PFAS using the laboratory model amphibian species Xenopus laevis. We had two primary aims: (1) to understand the developmental toxicity of a structurally diverse set of PFAS compounds in developing embryos and (2) to characterize the potential impacts of perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), and hexafluoropropylene oxide-dimer acid (HFPO-DA a.k.a. GenX), on growth and thyroid hormone-controlled metamorphosis. We employed a combination of static renewal and flow-through exposure designs. Embryos were exposed to 17 structurally diverse PFAS starting at the midblastula stage through the completion of organogenesis (96 h). To investigate impacts on PFOS, PFOA, PFHxS, and HFPO-DA on development and metamorphosis, larvae were exposed from premetamorphosis (Nieuwkoop Faber stage 51 or 54) through pro metamorphosis. Of the PFAS tested in embryos, only 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC10-diol) and perfluorohexanesulfonamide (FHxSA) exposure resulted in clear concentration-dependent developmental toxicity. For both of these PFAS, a significant increase in mortality was observed at 2.5 and 5 mg/L. For FC10-diol, 100% of the surviving embryos were malformed at 1.25 and 2.5 mg/L, while for FHxSA, a significant increase in malformations (100%) was observed at 2.5 and 5 mg/L. Developmental stage achieved was the most sensitive endpoint with significant effects observed at 1.25 and 0.625 mg/L for FC10-diol and FHxSA, respectively. In larval studies, we observed impacts on growth following exposure to PFHxS and PFOS at concentrations of 100 and 2.5 mg/L, respectively, while no impacts were observed in larvae when exposed to PFOA and HFPO-DA at concentration of 100 mg/L. Further, we did not observe impacts on thyroid endpoints in exposed larvae. These experiments have broadened our understanding of the impact of PFAS on anuran development.
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Embrião não Mamífero , Fluorocarbonos , Larva , Metamorfose Biológica , Xenopus laevis , Animais , Xenopus laevis/embriologia , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Fluorocarbonos/toxicidade , Embrião não Mamífero/efeitos dos fármacos , Metamorfose Biológica/efeitos dos fármacos , Ácidos Alcanossulfônicos/toxicidade , Ácidos Sulfônicos/toxicidade , Relação Dose-Resposta a Droga , Caprilatos/toxicidade , Desenvolvimento Embrionário/efeitos dos fármacos , Hormônios TireóideosRESUMO
OBJECTIVE: There is a high prevalence of cervical myelopathy that requires surgery; as such, it is important to identify how different groups benefit from surgery. The American Association of Neurological Surgeons launched the Quality Outcomes Database (QOD), a prospective longitudinal registry, that includes demographic, clinical, and patient-reported outcome data to measure the safety and quality of neurosurgical procedures. In this study, the authors assessed the impact of gender on patient-reported outcomes in patients who underwent surgery for cervical myelopathy. METHODS: The authors analyzed 1152 patients who underwent surgery for cervical myelopathy and were included in the QOD cervical module. Univariate comparison of baseline patient characteristics between males and females who underwent surgery for cervical spondylotic myelopathy was performed. Baseline characteristics that significantly differed between males and females were included in a multivariate generalized linear model comparing baseline and 1-year postoperative Neck Disability Index (NDI) scores. RESULTS: This study included 546 females and 604 males. Females demonstrated significantly greater improvement in NDI score 1 year after surgery (p = 0.036). In addition to gender, the presence of axial neck pain and insurance status were also significantly predictive of improvement in NDI score after surgery (p = 0.0013 and p = 0.0058, respectively). CONCLUSIONS: Females were more likely to benefit from surgery for cervical myelopathy compared with males. It is important to identify gender differences in postoperative outcomes after surgery in order to deliver more personalized and patient-centric care.
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Pescoço , Doenças da Medula Espinal , Masculino , Humanos , Feminino , Estudos Prospectivos , Vértebras Cervicais/cirurgia , Cervicalgia , Doenças da Medula Espinal/cirurgia , Resultado do TratamentoRESUMO
OBJECTIVE: The purpose of this study was to evaluate the performance of different supervised machine learning algorithms to predict achievement of minimum clinically important difference (MCID) in neck pain after surgery in patients with cervical spondylotic myelopathy (CSM). METHODS: This was a retrospective analysis of the prospective Quality Outcomes Database CSM cohort. The data set was divided into an 80% training and a 20% test set. Various supervised learning algorithms (including logistic regression, support vector machine, decision tree, random forest, extra trees, gaussian naïve Bayes, k-nearest neighbors, multilayer perceptron, and extreme gradient boosted trees) were evaluated on their performance to predict achievement of MCID in neck pain at 3 and 24 months after surgery, given a set of predicting baseline features. Model performance was assessed with accuracy, F1 score, area under the receiver operating characteristic curve, precision, recall/sensitivity, and specificity. RESULTS: In total, 535 patients (46.9%) achieved MCID for neck pain at 3 months and 569 patients (49.9%) achieved it at 24 months. In each follow-up cohort, 501 patients (93.6%) were satisfied at 3 months after surgery and 569 patients (100%) were satisfied at 24 months after surgery. Of the supervised machine learning algorithms tested, logistic regression demonstrated the best accuracy (3 months: 0.76 ± 0.031, 24 months: 0.773 ± 0.044), followed by F1 score (3 months: 0.759 ± 0.019, 24 months: 0.777 ± 0.039) and area under the receiver operating characteristic curve (3 months: 0.762 ± 0.027, 24 months: 0.773 ± 0.043) at predicting achievement of MCID for neck pain at both follow-up time points, with fair performance. The best precision was also demonstrated by logistic regression at 3 (0.724 ± 0.058) and 24 (0.780 ± 0.097) months. The best recall/sensitivity was demonstrated by multilayer perceptron at 3 months (0.841 ± 0.094) and by extra trees at 24 months (0.817 ± 0.115). Highest specificity was shown by support vector machine at 3 months (0.952 ± 0.013) and by logistic regression at 24 months (0.747 ± 0.18). CONCLUSIONS: Appropriate selection of models for studies should be based on the strengths of each model and the aims of the studies. For maximally predicting true achievement of MCID in neck pain, of all the predictions in this balanced data set the appropriate metric for the authors' study was precision. For both short- and long-term follow-ups, logistic regression demonstrated the highest precision of all models tested. Logistic regression performed consistently the best of all models tested and remains a powerful model for clinical classification tasks.
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Cervicalgia , Doenças da Medula Espinal , Humanos , Estudos Retrospectivos , Estudos Prospectivos , Cervicalgia/diagnóstico , Cervicalgia/cirurgia , Teorema de Bayes , Aprendizado de Máquina Supervisionado , Algoritmos , Doenças da Medula Espinal/cirurgiaRESUMO
OBJECTIVE: The authors sought to compare 3-level anterior with posterior fusion surgical procedures for the treatment of multilevel cervical spondylotic myelopathy (CSM). METHODS: The authors analyzed prospective data from the 14 highest enrolling sites of the Quality Outcomes Database CSM module. They compared 3-level anterior cervical discectomy and fusion (ACDF) and posterior cervical laminectomy and fusion (PCF) surgical procedures, excluding surgical procedures crossing the cervicothoracic junction. Rates of reaching the minimal clinically important difference (MCID) in patient-reported outcomes (PROs) were compared at 24 months postoperatively. Multivariable analyses adjusted for potential confounders elucidated in univariable analysis. RESULTS: Overall, 199 patients met the inclusion criteria: 123 ACDF (61.8%) and 76 PCF (38.2%) patients. The 24-month follow-up rates were similar (ACDF 90.2% vs PCF 92.1%, p = 0.67). Preoperatively, ACDF patients were younger (60.8 ± 10.2 vs 65.0 ± 10.3 years, p < 0.01), and greater proportions were privately insured (56.1% vs 36.8%, p = 0.02), actively employed (39.8% vs 22.8%, p = 0.04), and independently ambulatory (14.6% vs 31.6%, p < 0.01). Otherwise, the cohorts had equivalent baseline modified Japanese Orthopaedic Association (mJOA), Neck Disability Index (NDI), numeric rating scale (NRS)-arm pain, NRS-neck pain, and EQ-5D scores (p > 0.05). ACDF patients had reduced hospitalization length (1.6 vs 3.9 days, p < 0.01) and a greater proportion had nonroutine discharge (7.3% vs 22.8%, p < 0.01), but they had a higher rate of postoperative dysphagia (13.5% vs 3.5%, p = 0.049). Compared with baseline values, both groups demonstrated improvements in all outcomes at 24 months (p < 0.05). In multivariable analyses, after controlling for age, insurance payor, employment status, ambulation status, and other potential clinically relevant confounders, ACDF was associated with a greater proportion of patients with maximum satisfaction on the North American Spine Society Patient Satisfaction Index (NASS) (NASS score of 1) at 24 months (69.4% vs 53.7%, OR 2.44, 95% CI 1.17-5.09, adjusted p = 0.02). Otherwise, the cohorts shared similar 24-month outcomes in terms of reaching the MCID for mJOA, NDI, NRS-arm pain, NRS-neck pain, and EQ-5D score (adjusted p > 0.05). There were no differences in the 3-month readmission (ACDF 4.1% vs PCF 3.9%, p = 0.97) and 24-month reoperation (ACDF 13.5% vs PCF 18.6%, p = 0.36) rates. CONCLUSIONS: In a cohort limited to 3-level fusion surgical procedures, ACDF was associated with reduced blood loss, shorter hospitalization length, and higher routine home discharge rates; however, PCF resulted in lower rates of postoperative dysphagia. The procedures yielded comparably significant improvements in functional status (mJOA score), neck and arm pain, neck pain-related disability, and quality of life at 3, 12, and 24 months. ACDF patients had significantly higher odds of maximum satisfaction (NASS score 1). Given comparable outcomes, patients should be counseled on each approach's complication profile to aid in surgical decision-making.
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Multiphoton entangled quantum states are key to advancing quantum technologies such as multiparty quantum communications, quantum sensing, or quantum computation. Their scalable generation, however, remains an experimental challenge. Current methods for generating these states rely on stitching together photons from probabilistic sources, and state generation rates drop exponentially in the number of photons. Here, we implement a system based on active feed-forward and multiplexing that addresses this challenge. We demonstrate the scalable generation of four-photon and six-photon Greenberger-Horne-Zeilinger states, increasing generation rates by factors of 9 and 35, respectively. This is consistent with the exponential enhancement compared to the standard nonmultiplexed approach that is predicted by our theory. These results facilitate the realization of practical multiphoton protocols for photonic quantum technologies.
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We devise an approach to characterizing the intricate interplay between classical and quantum interference of two-photon states in a network, which comprises multiple time-bin modes. By controlling the phases of delocalized single photons, we manipulate the global mode structure, resulting in distinct two-photon interference phenomena for time-bin resolved (local) and time-bucket (global) coincidence detection. This coherent control over the photons' mode structure allows for synthesizing two-photon interference patterns, where local measurements yield standard Hong-Ou-Mandel dips while the global two-photon visibility is governed by the overlap of the delocalized single-photon states. Thus, our experiment introduces a method for engineering distributed quantum interferences in networks.
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BACKGROUND: Ischemic stroke provokes a neuroinflammatory response and simultaneously promotes release of epinephrine and norepinephrine by the sympathetic nervous system. This increased sympathetic outflow can act on ß2-adrenergic receptors expressed by immune cells such as brain-resident microglia and monocyte-derived macrophages (MDMs), but the effect on post-stroke neuroinflammation is unknown. Thus, we investigated how changes in ß2-adrenergic signaling after stroke onset influence the microglia/MDM stroke response, and the specific importance of microglia/MDM ß2-adrenergic receptors to post-stroke neuroinflammation. METHODS: To investigate the effects of ß2-adrenergic receptor manipulation on post-stroke neuroinflammation, we administered the ß2-adrenergic receptor agonist clenbuterol to mice 3 h after the onset of photothrombotic stroke. We immunostained to quantify microglia/MDM numbers and proliferation and to assess morphology and activation 3 days later. We assessed stroke outcomes by measuring infarct volume and functional motor recovery and analyzed gene expression levels of neuroinflammatory molecules. Finally, we evaluated changes in cytokine expression and microglia/MDM response in brains of mice with selective knockout of the ß2-adrenergic receptor from microglia and monocyte-lineage cells. RESULTS: We report that clenbuterol treatment after stroke onset causes enlarged microglia/MDMs and impairs their proliferation, resulting in reduced numbers of these cells in the peri-infarct cortex by 1.7-fold at 3 days after stroke. These changes in microglia/MDMs were associated with increased infarct volume in clenbuterol-treated animals. In mice that had the ß2-adrenergic receptor specifically knocked out of microglia/MDMs, there was no change in morphology or numbers of these cells after stroke. However, knockdown of ß2-adrenergic receptors in microglia and MDMs resulted in increased expression of TNFα and IL-10 in peri-infarct tissue, while stimulation of ß2-adrenergic receptors with clenbuterol had the opposite effect, suppressing TNFα and IL-10 expression. CONCLUSIONS: We identified ß2-adrenergic receptor signaling as an important regulator of the neuroimmune response after ischemic stroke. Increased ß2-adrenergic signaling after stroke onset generally suppressed the microglia/MDM response, reducing upregulation of both pro- and anti-inflammatory cytokines, and increasing stroke size. In contrast, diminished ß2-adrenergic signaling in microglia/MDMs augmented both pro- and anti-inflammatory cytokine expression after stroke. The ß2-adrenergic receptor may therefore present a therapeutic target for improving the post-stroke neuroinflammatory and repair process.
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Agonistas Adrenérgicos beta/farmacologia , Isquemia Encefálica/imunologia , Mediadores da Inflamação/imunologia , Receptores Adrenérgicos beta 2/imunologia , Transdução de Sinais/fisiologia , Acidente Vascular Cerebral/imunologia , Animais , Isquemia Encefálica/metabolismo , Isquemia Encefálica/patologia , Mediadores da Inflamação/antagonistas & inibidores , Mediadores da Inflamação/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Receptores Adrenérgicos beta 2/metabolismo , Transdução de Sinais/efeitos dos fármacos , Acidente Vascular Cerebral/metabolismo , Acidente Vascular Cerebral/patologiaRESUMO
Detecting light is fundamental to all optical experiments and applications. At the single photon level, the quantized nature of light requires specialised detectors, which typically saturate when more than one photon is incident. Here, we report on a massively-multiplexed single-photon detector, which exploits the saturation regime of a single click detector to exhibit a dynamic range of 123 dB, enabling measurement from optical energies as low as 10- 7 photons per pulse to â¼ 2.5 × 105photons per pulse. This allows us to calibrate a single photon detector directly to a power meter, as well as characterize the nonclassical features of a variety of quantum states.
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We report on the first experimental reconstruction of an entanglement quasiprobability. In contrast to related techniques, the negativities in our distributions are a necessary and sufficient identifier of separability and entanglement and enable a full characterization of the quantum state. A reconstruction algorithm is developed, a polarization Bell state is prepared, and its entanglement is certified based on the reconstructed entanglement quasiprobabilities, with a high significance and without correcting for imperfections.
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Downy mildew is a yield-limiting disease of sunflower, caused by the pathogen Plasmopara halstedii. Zoospore infection of root tissue shortly after planting results in systemic infection, causing postemergence damping off or severe stunting and head sterility. Although fungicide-applied seed treatments can be an effective management tool, the pathogen is resistant to phenylamide fungicides in many growing regions, and other available fungicides have limited efficacy. Oxathiapiprolin, the first member of the piperidinyl thiazole isoxazoline fungicides, was evaluated for efficacy on downy mildew in field trials conducted from 2011 to 2015 in North Dakota. Throughout the course of the study, the rate range was narrowed from active ingredient (a.i.) at 0.45 to 116.0 µg a.i. seed-1 to an optimal effective rate of 9.37 to 18.75 µg a.i. seed-1. Within that optimal range, the downy mildew incidence of sunflower planted with oxathiapiprolin-treated seed was significantly lower than the incidence in the nontreated sunflower in all 11 trials with disease pressure. Additionally, downy mildew incidence of sunflower planted with oxathiapiprolin-treated seed was significantly lower than sunflower planted with competitive commercially available fungicide-treated seed in 10 of those 11 trials. The use of oxathiapiprolin by sunflower growers is likely to reduce disease incidence and subsequent yield loss to downy mildew.
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Helianthus , Hidrocarbonetos Fluorados , Oomicetos , Doenças das Plantas , Pirazóis , Antiparasitários/farmacologia , Helianthus/parasitologia , Hidrocarbonetos Fluorados/farmacologia , North Dakota , Oomicetos/efeitos dos fármacos , Doenças das Plantas/parasitologia , Doenças das Plantas/prevenção & controle , Pirazóis/farmacologia , Sementes/químicaRESUMO
Heralded single photon sources are often implemented using spontaneous parametric downconversion, but their quality can be restricted by optical loss, double pair emission and detector dark counts. Here, we propose a scheme using cascaded downconversion that would improve the performance of such sources by providing a second trigger signal to herald the presence of a single photon, thereby reducing the effects of detector dark counts. Our calculations show that for a setup with fixed detectors, an improved heralded second-order correlation function g(2) can be achieved with cascaded downconversion given sufficient efficiency for the second downconversion, even for equal single-photon production rates. Furthermore, the minimal g(2) value is unchanged for a large range in pump beam intensity. These results are interesting for applications where achieving low, stable values of g(2) is of primary importance.
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Entangled photon pair sources based on bulk optics are approaching optimal design and implementation, with high state fidelities, spectral purities and heralding efficiencies, but generally low brightness. Integrated entanglement sources, while providing higher brightness and low-power operation, often sacrifice performance in output state quality and coupling efficiency. Here we present a polarization-entangled pair source based on a hybrid approach of waveguiding and bulk optics, addressing every metric simultaneously. We show 96 % fidelity to the singlet state, 82 % Hong-Ou-Mandel interference visibility, 43 % average Klyshko efficiency, and a high brightness of 2.9 × 106 pairs/(mode·s·mW), while requiring only microwatts of pump power.
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Multiparticle quantum interference is critical for our understanding and exploitation of quantum information, and for fundamental tests of quantum mechanics. A remarkable example of multi-partite correlations is exhibited by the Greenberger-Horne-Zeilinger (GHZ) state. In a GHZ state, three particles are correlated while no pairwise correlation is found. The manifestation of these strong correlations in an interferometric setting has been studied theoretically since 1990 but no three-photon GHZ interferometer has been realized experimentally. Here we demonstrate three-photon interference that does not originate from two-photon or single photon interference. We observe phase-dependent variation of three-photon coincidences with (92.7±4.6)% visibility in a generalized Franson interferometer using energy-time entangled photon triplets. The demonstration of these strong correlations in an interferometric setting provides new avenues for multiphoton interferometry, fundamental tests of quantum mechanics, and quantum information applications in higher dimensions.
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We present an implementation of photonic qubit precertification that performs the delicate task of detecting the presence of a flying photon without destroying its qubit state, allowing loss-sensitive quantum cryptography and tests of nonlocality even over long distance. By splitting an incoming single photon in two via parametric down-conversion, we herald the photon's arrival from an independent photon source while preserving its quantum information with up to (92.3±0.6)% fidelity. With reduced detector dark counts, precertification will be immediately useful in quantum communication.
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AIM: The neural cardiac therapy for heart failure (NECTAR-HF) was a randomized sham-controlled trial designed to evaluate whether a single dose of vagal nerve stimulation (VNS) would attenuate cardiac remodelling, improve cardiac function and increase exercise capacity in symptomatic heart failure patients with severe left ventricular (LV) systolic dysfunction despite guideline recommended medical therapy. METHODS: Patients were randomized in a 2 : 1 ratio to receive therapy (VNS ON) or control (VNS OFF) for a 6-month period. The primary endpoint was the change in LV end systolic diameter (LVESD) at 6 months for control vs. therapy, with secondary endpoints of other echocardiography measurements, exercise capacity, quality-of-life assessments, 24-h Holter, and circulating biomarkers. RESULTS: Of the 96 implanted patients, 87 had paired datasets for the primary endpoint. Change in LVESD from baseline to 6 months was -0.04 ± 0.25 cm in the therapy group compared with -0.08 ± 0.32 cm in the control group (P = 0.60). Additional echocardiographic parameters of LV end diastolic dimension, LV end systolic volume, left ventricular end diastolic volume, LV ejection fraction, peak V02, and N-terminal pro-hormone brain natriuretic peptide failed to show superiority compared to the control group. However, there were statistically significant improvements in quality of life for the Minnesota Living with Heart Failure Questionnaire (P = 0.049), New York Heart Association class (P = 0.032), and the SF-36 Physical Component (P = 0.016) in the therapy group. CONCLUSION: Vagal nerve stimulation as delivered in the NECTAR-HF trial failed to demonstrate a significant effect on primary and secondary endpoint measures of cardiac remodelling and functional capacity in symptomatic heart failure patients, but quality-of-life measures showed significant improvement.
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Insuficiência Cardíaca/terapia , Estimulação do Nervo Vago/métodos , Eletrocardiografia Ambulatorial , Tolerância ao Exercício/fisiologia , Feminino , Insuficiência Cardíaca/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Segurança do Paciente , Qualidade de Vida , Resultado do Tratamento , Estimulação do Nervo Vago/efeitos adversos , Disfunção Ventricular Esquerda/fisiopatologia , Disfunção Ventricular Esquerda/terapia , Remodelação Ventricular/fisiologiaRESUMO
We present a loophole-free violation of local realism using entangled photon pairs. We ensure that all relevant events in our Bell test are spacelike separated by placing the parties far enough apart and by using fast random number generators and high-speed polarization measurements. A high-quality polarization-entangled source of photons, combined with high-efficiency, low-noise, single-photon detectors, allows us to make measurements without requiring any fair-sampling assumptions. Using a hypothesis test, we compute p values as small as 5.9×10^{-9} for our Bell violation while maintaining the spacelike separation of our events. We estimate the degree to which a local realistic system could predict our measurement choices. Accounting for this predictability, our smallest adjusted p value is 2.3×10^{-7}. We therefore reject the hypothesis that local realism governs our experiment.
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Phomopsis stem canker causes yield reductions on sunflower (Helianthus annuus L.) on several continents, including Australia, Europe, and North America. In the United States, Phomopsis stem canker incidence has increased 16-fold in the Northern Great Plains between 2001 and 2012. Although Diaporthe helianthi was assumed to be the sole causal agent in the United States, a newly described species, D. gulyae, was found to be the primary cause of Phomopsis stem canker in Australia. To determine the identity of Diaporthe spp. causing Phomopsis stem canker in the Northern Great Plains, 275 infected stems were collected between 2010 and 2012. Phylogenetic analyses of sequences of the ribosomal DNA internal transcribed spacer region, elongation factor subunit 1-α, and actin gene regions of representative isolates, in comparison with those of type specimens, confirmed two species (D. helianthi and D. gulyae) in the United States. Differences in aggressiveness between the two species were determined using the stem-wound method in the greenhouse; overall, D. helianthi and D. gulyae did not vary significantly (P≤0.05) in their aggressiveness at 10 and 14 days after inoculation. These findings indicate that both Diaporthe spp. have emerged as sunflower pathogens in the United States, and have implications on the management of this disease.
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Ascomicetos/genética , Helianthus/microbiologia , Ascomicetos/patogenicidade , Interações Hospedeiro-Patógeno , Filogenia , Doenças das Plantas , Estados UnidosRESUMO
Sunflower rust is an important yield-limiting disease in sunflower production in the Great Plains of the United States. Rust severity and incidence have increased between 2002 and 2011, and genetic resistance is limited in most commercial hybrids, particularly the high-value confectionary market type. Although fungicides are available for rust management in the United States, management recommendations are insufficient. Specifically, efficacy and timing data are very limited for fungicides in FRAC groups 7 and 11. Seventeen fungicide efficacy and timing trials were conducted between 2008 and 2011 in North Dakota. Timings evaluated across the four years included single or multiple applications at growth stages (GS): GS V8-V12 (late vegetative), GS R1 (terminal bud formation), GS R3-4 (elongation of bud), GS R5 (flowering), and GS R6 (completion of flowering). With few exceptions, fungicide applications of DMIs and QoIs controlled disease greater than SDHI fungicides. Fungicide applications made at R5, either singly or in combination, consistently resulted in greater disease control. A negative correlation (r = -0.7756) between disease control and yield was observed, resulting in a yield reduction of 6.6% for every 1% increase in disease severity.
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Objectives Virtual reality (VR) is an increasingly valuable teaching tool, but current simulators are not typically clinically scalable due to their reliance on inefficient manual segmentation. The objective of this project was to leverage a high-throughput and accurate machine learning method to automate data preparation for a patient-specific VR simulator used to explore preoperative sinus anatomy. Methods An endoscopic VR simulator was designed in Unity to enable interactive exploration of sinus anatomy. The Saak transform, a data-efficient machine learning method, was adapted to accurately segment sinus computed tomography (CT) scans using minimal training data, and the resulting data were reconstructed into three-dimensional (3D) patient-specific models that could be explored in the simulator. Results Using minimal training data, the Saak transform-based machine learning method offers accurate soft-tissue segmentation. When explored with an endoscope in the VR simulator, the anatomical models generated by the algorithm accurately capture key sinus structures and showcase patient-specific variability in anatomy. Conclusion By offering an automatic means of preparing VR models from a patient's raw CT scans, this pipeline takes a key step toward clinical scalability. In addition to preoperative planning, this system also enables virtual endoscopy-a tool that is particularly useful in the COVID-19 era. As VR technology inevitably continues to develop, such a foundation will help ensure that future innovations remain clinically accessible.
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BACKGROUND: The comparative effectiveness of decompression plus lumbar facet arthroplasty versus decompression plus instrumented lumbar spinal fusion in patients with lumbar spinal stenosis and grade-I degenerative spondylolisthesis is unknown. METHODS: In this randomized, controlled, Food and Drug Administration Investigational Device Exemption trial, we assigned patients who had single-level lumbar spinal stenosis and grade-I degenerative spondylolisthesis to undergo decompression plus lumbar facet arthroplasty (arthroplasty group) or decompression plus fusion (fusion group). The primary outcome was a predetermined composite clinical success score. Secondary outcomes included the Oswestry Disability Index (ODI), visual analog scale (VAS) back and leg pain, Zurich Claudication Questionnaire (ZCQ), Short Form (SF)-12, radiographic parameters, surgical variables, and complications. RESULTS: A total of 321 adult patients were randomized in a 2:1 fashion, with 219 patients assigned to undergo facet arthroplasty and 102 patients assigned to undergo fusion. Of these, 113 patients (51.6%) in the arthroplasty group and 47 (46.1%) in the fusion group who had either reached 24 months of postoperative follow-up or were deemed early clinical failures were included in the primary outcome analysis. The arthroplasty group had a higher proportion of patients who achieved composite clinical success than did the fusion group (73.5% versus 25.5%; p < 0.001), equating to a between-group difference of 47.9% (95% confidence interval, 33.0% to 62.8%). The arthroplasty group outperformed the fusion group in most patient-reported outcome measures (including the ODI, VAS back pain, and all ZCQ component scores) at 24 months postoperatively. There were no significant differences between groups in surgical variables or complications, except that the fusion group had a higher rate of developing symptomatic adjacent segment degeneration. CONCLUSIONS: Among patients with lumbar spinal stenosis and grade-I degenerative spondylolisthesis, lumbar facet arthroplasty was associated with a higher rate of composite clinical success than fusion was at 24 months postoperatively. LEVEL OF EVIDENCE: Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.