2,144 research outputs found
Far field imaging by a planar lens: diffraction versus superresolution
We resolve the long standing controversy regarding the imaging by a planar
lens made of left-handed media and demonstrate theoretically that its far field
image has a fundamentally different origin depending on the relationship
between losses {inside} the lens and the wavelength of the light . At
small enough the image is always governed by diffraction theory, and
the resolution is independent of the absorption if both Im and
Im. For any finite , however, a critical absorption exists
below which the superresolution regime takes place, though this absorption is
extremely low and can hardly be achieved. We demonstrate that the transition
between diffraction limited and superresolution regimes is governed by {the}
universal parameter combining absorption, wavelength, and lens thickness.
Finally, we show that this parameter is related to the resonant excitation of
the surface plasma waves
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Modeling and Designing Components with Locally Controlled Composition
SFF processes have demonstrated the ability to produce parts with locally controlled
composition. In the limit, processes such as 3D Printing,cancreate parts with composition
control on thelength scaleiof 100 microns.ToexploitthispC)tential,~e\\ZJnethodsto rnod~l,
exchange, and process parts.with local composition needtobe.deyeloped..... Anapproachtc)
modeling a part's geometty,.topology, and composition will be presented.· This.approachis
based on sUbdividing the solidmodel into sub-regions and associating analytic composition
blending functions \\lith each region. These blending functions definethe composition
throughout the model as mixtures ofthe primary materials available to·the SEF machine.
Various design tools will also be presented, for example, specification of com~ositionasa
function of the distance from the surface of a part. Finally,the role of design rules specifying
maximum concentrations and concentration.gradients will be discussed.Mechanical Engineerin
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Targeted sequence design within the coarse-grained polymer genome
The chemical design of polymers with target structural and/or functional properties represents a grand challenge in materials science. While data-driven design approaches are promising, success with polymers has been limited, largely due to limitations in data availability. Here, we demonstrate the targeted sequence design of single-chain structure in polymers by combining coarse-grained modeling, machine learning, and model optimization. Nearly 2000 unique coarse-grained polymers are simulated to construct and analyze machine learning models. We find that deep neural networks inexpensively and reliably predict structural properties with limited sequence information as input. By coupling trained ML models with sequential model-based optimization, polymer sequences are proposed to exhibit globular, swollen, or rod-like behaviors, which are verified by explicit simulations. This work highlights the promising integration of coarse-grained modeling with data-driven design and represents a necessary and crucial step toward more complex polymer design efforts
Success With Extended-Infusion Meropenem After Recurrence of Baclofen Pump-Related Achromobacter Xylosoxidans Meningitis in an Adolescent
A 13-year-old female experienced a recurrence of baclofen pump-related central nervous system (CNS) infection caused by Achromobacter, despite absence of retained foreign material. Due to the failure of meropenem (120 mg/kg/d in divided doses every 8 hours and infused over 30 minutes) in the initial infection, the dose was infused over 4 hours during the recurrence. Meropenem is an antibiotic for which efficacy is time dependent, and 4-hour versus 30-minute infusions have been shown to prolong the time the concentration of the antibiotic exceeds the minimum inhibitory concentration (MIC) of the organism at the site of infection (T\u3eMIC). Meropenem serum concentrations were obtained and indicated that T\u3eMIC was at least 75% of the dosing interval. Our patient improved with no noted recurrences or adverse effects on the extended-infusion meropenem regimen. Utilization of extended-infusion beta-lactam dosing whenever possible in the treatment of serious infections caused by gram-negative organisms should be considered, as this dosing appears to be safe and improves the probability of achieving pharmacokinetic/pharmacodynamic goals
Laboratory-directed evolution as a tool for anticipating insecticide resistance
The evolution of insecticide resistance provides a eukaryotic model system for studying enzyme evolution. Understanding the molecular basis of insecticide resistance can assist both the development of new methods to combat resistance and the anticipation of future resistance. Three insect species have independently evolved catalytic organophosphate (OP) insecticide resistance through a single active-site mutation (Gly\u3eAsp) in the αE7 enzyme1-3. To explore the evolutionary potential of αE7, we subjected αE7 from the blowfly Lucilia cuprina to nine rounds of mutation and selection, resulting in a \u3e1000-fold increase in OP-hydrolase activity and a kcat / KM \u3e 106 M-1 min-1. Kinetic and structural analysis of the evolutionary trajectory revealed the molecular basis for the increase in catalytic efficiency. Mutations occurring in the early stages of the trajectory enrich the productive side chain conformation of the key aspartic acid residue, while mutations in later stages remodel the binding pocket. Remarkably, mutations appearing in the later rounds yielded larger improvements in catalytic efficiency compared to initial mutations, indicating that the initial Gly\u3eAsp mutation represents only a fraction of the αE7 evolutionary potential. Worryingly, this suggests that the Gly\u3eAsp could be the first of many steps toward efficient OP-insecticide detoxification.
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Investigation of the chemocatalytic and biocatalytic valorization of a range of different lignin preparations: The importance of β-O-4 content
A set of seven different lignin preparations was generated from a range of organosolv (acidic, alkaline, ammonia-treated, and dioxane-based), ionic liquid, autohydrolysis, and Kraft pretreatments of lignocelluloses. Each lignin was characterized by 2D HSQC NMR spectroscopy, showing significant variability in the β-O-4 content of the different lignin samples. Each lignin was then valorised using three biocatalytic methods (microbial biotransformation with Rhodococcus jostii RHA045, treatment with Pseudomonas fluorescens Dyp1B or Sphingobacterium sp. T2 manganese superoxide dismutase) and two chemocatalytic methods (catalytic hydrogenation using Pt/alumina catalyst, DDQ benzylic oxidation/Zn reduction). Highest product yields for DDQ/Zn valorization were observed from poplar ammonia percolation-organosolv lignin, which had the highest β-O-4 content of the investigated lignins and also gave the highest yield of syringaldehyde (243 mg L -1 ) when using R. jostii RHA045 and the most enzymatic products using P. fluorescens Dyp1B. The highest product yield from the Pt/alumina hydrogenation was observed using oak dioxasolv lignin, which also had a high β-O-4 content. In general, highest product yields for both chemocatalytic and biocatalytic valorization methods were obtained from preparations that showed highest β-O-4 content, while variable yields were obtained with preparations containing intermediate β-O-4 content, and little or no product was obtained with preparations containing low β-O-4 content
Pole dancing for fitness: The physiological and metabolic demand of a 60-minute class
Nicholas, JC, McDonald, KA, Peeling, P, Jackson, B, Dimmock, JA, Alderson, JA, and Donnelly, CJ. Pole dancing for fitness: The physiological and metabolic demand of a 60-minute class. J Strength Cond Res 33(10): 2704–2710, 2019—Little is understood about the acute physiological or metabolic demand of pole dancing classes. As such, the aims of this study were to quantify the demands of a standardized recreational pole dancing class, classifying outcomes according to American College of Sports Medicine (ACSM) exercise-intensity guidelines, and to explore differences in physiological and metabolic measures between skill- and routine-based class components. Fourteen advanced-level amateur female pole dancers completed three 60-minute standardized pole dancing classes. In one class, participants were fitted with a portable metabolic analysis unit. Overall, classes were performed at a mean Vo2 of 16.0 ml·kg−1·min−1, total energy cost (EC) of 281.6 kcal (4.7 kcal·min−1), metabolic equivalent (METs) of 4.6, heart rate of 131 b·min−1, rate of perceived exertion (RPE) of 6.3/10, and blood lactate of 3.1 mM. When comparing skill- and routine-based components of the class, EC per minute (4.4 vs. 5.3 kcal·min−1), peak Vo2 (21.5 vs. 29.6 ml·kg−1·min−1), METs (4.3 vs. 5.2), and RPE (7.2 vs. 8.4) were all greater in the routine-based component (p \u3c 0.01), indicating that classes with an increased focus on routine-based training, as compared to skill-based training, may benefit those seeking to exercise at a higher intensity level, resulting in greater caloric expenditure. In accordance with ASCM guidelines, an advanced-level 60-minute pole dancing class can be classified as a moderate-intensity cardiorespiratory exercise; when completed for ≥ 30 minutes, ≥ 5 days per week (total ≥ 150 minutes) satisfies the recommended level of exercise for improved health and cardiorespiratory fitness
Pole dancing for fitness: The physiological and metabolic demand of a 60-minute class
Nicholas, JC, McDonald, KA, Peeling, P, Jackson, B, Dimmock, JA, Alderson, JA, and Donnelly, CJ. Pole dancing for fitness: The physiological and metabolic demand of a 60-minute class. J Strength Cond Res 33(10): 2704–2710, 2019—Little is understood about the acute physiological or metabolic demand of pole dancing classes. As such, the aims of this study were to quantify the demands of a standardized recreational pole dancing class, classifying outcomes according to American College of Sports Medicine (ACSM) exercise-intensity guidelines, and to explore differences in physiological and metabolic measures between skill- and routine-based class components. Fourteen advanced-level amateur female pole dancers completed three 60-minute standardized pole dancing classes. In one class, participants were fitted with a portable metabolic analysis unit. Overall, classes were performed at a mean Vo2 of 16.0 ml·kg−1·min−1, total energy cost (EC) of 281.6 kcal (4.7 kcal·min−1), metabolic equivalent (METs) of 4.6, heart rate of 131 b·min−1, rate of perceived exertion (RPE) of 6.3/10, and blood lactate of 3.1 mM. When comparing skill- and routine-based components of the class, EC per minute (4.4 vs. 5.3 kcal·min−1), peak Vo2 (21.5 vs. 29.6 ml·kg−1·min−1), METs (4.3 vs. 5.2), and RPE (7.2 vs. 8.4) were all greater in the routine-based component (p \u3c 0.01), indicating that classes with an increased focus on routine-based training, as compared to skill-based training, may benefit those seeking to exercise at a higher intensity level, resulting in greater caloric expenditure. In accordance with ASCM guidelines, an advanced-level 60-minute pole dancing class can be classified as a moderate-intensity cardiorespiratory exercise; when completed for ≥ 30 minutes, ≥ 5 days per week (total ≥ 150 minutes) satisfies the recommended level of exercise for improved health and cardiorespiratory fitness
Web-Based Psychological Interventions for People Living With and Beyond Cancer:Meta-Review of What Works and What Does Not for Maximizing Recruitment, Engagement, and Efficacy
BACKGROUND: Despite high levels of psychological distress experienced by many patients with cancer, previous research has identified several barriers to accessing traditional face-to-face psychological support. Web-based psychosocial interventions have emerged as a promising alternative. OBJECTIVE: This meta-review aimed to synthesize evidence on recruitment challenges and enablers, factors that promote engagement and adherence to web-based intervention content, and factors that promote the efficacy of web-based psychosocial interventions for patients with cancer and cancer survivors. METHODS: We conducted a systematic search of previous reviews that investigated the recruitment, engagement, and efficacy of web-based and app-based psychosocial interventions in adult patients with cancer and cancer survivors. We searched PubMed, CINAHL, PsycINFO, and the Cochrane Library database for relevant literature. The search terms focused on a combination of topics pertaining to neoplasms and telemedicine. Two independent authors conducted abstract screening, full text screening, and data extraction for each identified article. RESULTS: A total of 20 articles met eligibility criteria. There was inconsistency in the reporting of uptake and engagement data; however, anxiety about technology and perceived time burden were identified as 2 key barriers. Web-based psychosocial oncology interventions demonstrated efficacy in reducing depression and stress but reported weak to mixed findings for distress, anxiety, quality of life, and well-being. Although no factors consistently moderated intervention efficacy, preliminary evidence indicated that multicomponent interventions and greater communication with a health care professional were preferred by participants and were associated with superior effects. CONCLUSIONS: Several consistently cited barriers to intervention uptake and recruitment have emerged, which we recommend future intervention studies address. Preliminary evidence also supports the superior efficacy of multicomponent interventions and interventions that facilitate communication with a health care professional. However, a greater number of appropriately powered clinical trials, including randomized trials with head-to-head comparisons, are needed to enable more confident conclusions regarding which web-based psychosocial oncology interventions work best and for whom. TRIAL REGISTRATION: PROSPERO CRD42020202633; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=20263
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New Sequence Perspective on the Devonian Reef Complex and the Frasnian-Famennian Boundary, Canning Basin, Australia
The application of concepts of sequence stratigraphy to seismic and well data has led to a new understanding of the subsurface Devonian reef complex of the Canning Basin. It demonstrates marked reciprocal sedimentation with lowstand terrigenous sediments largely restricted to the basin and transgressive and highstand carbonate sediments on the platform. Preliminary outcrop studies indicate the potential of these concepts to modify significantly the existing lithostratigraphic and biostratigraphic interpretations of this classic exhumed reef complex, including the stratigraphic context of the Frasnian-Famennian boundary in the Canning Basin
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