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1.
Astrophys J ; 967(2): 101, 2024 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-38799617

RESUMEN

M15 is a globular cluster with a known spread in neutron-capture elements. This paper presents abundances of neutron-capture elements for 62 stars in M15. Spectra were obtained with the Michigan/Magellan Fiber System spectrograph, covering a wavelength range from ∼4430 to 4630 Å. Spectral lines from Fe i, Fe ii, Sr i, Zr ii, Ba ii, La ii, Ce ii, Nd ii, Sm ii, Eu ii, and Dy ii were measured, enabling classifications and neutron-capture abundance patterns for the stars. Of the 62 targets, 44 are found to be highly Eu-enhanced r-II stars, another 17 are moderately Eu-enhanced r-I stars, and one star is found to have an s-process signature. The neutron-capture patterns indicate that the majority of the stars are consistent with enrichment by the r-process. The 62 target stars are found to show significant star-to-star spreads in Sr, Zr, Ba, La, Ce, Nd, Sm, Eu, and Dy, but no significant spread in Fe. The neutron-capture abundances are further found to have slight correlations with sodium abundances from the literature, unlike what has been previously found; follow-up studies are needed to verify this result. The findings in this paper suggest that the Eu-enhanced stars in M15 were enhanced by the same process, that the nucleosynthetic source of this Eu pollution was the r-process, and that the r-process source occurred as the first generation of cluster stars was forming.

2.
Environ Sci Technol ; 58(22): 9679-9688, 2024 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-38776554

RESUMEN

Wildfires produce solid residuals that have unique chemical and physical properties compared to unburned materials, which influence their cycling and fate in the natural environment. Visual burn severity assessment is used to evaluate post-fire alterations to the landscape in field-based studies, yet muffle furnace methods are commonly used in laboratory studies to assess molecular scale alterations along a temperature continuum. Here, we examined solid and leachable organic matter characteristics from chars visually characterized as low burn severity that were created either on an open air burn table or from low-temperature muffle furnace burns. We assessed how the different combustion conditions influence solid and dissolved organic matter chemistries and explored the potential influence of these results on the environmental fate and reactivity. Notably, muffle furnace chars produced less leachable carbon and nitrogen than open air chars across land cover types. Organic matter produced from muffle furnace burns was more homogeneous than open air chars. This work highlights chemical heterogeneities that exist within a single burn severity category, potentially influencing our conceptual understanding of pyrogenic organic matter cycling in the natural environment, including transport and processing in watersheds. Therefore, we suggest that open air burn studies are needed to further advance our understanding of pyrogenic organic matter's environmental reactivity and fate.


Asunto(s)
Incendios Forestales , Compuestos Orgánicos
3.
Ecol Appl ; 34(4): e2973, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38616644

RESUMEN

The combined effects of Indigenous fire stewardship and lightning ignitions shaped historical fire regimes, landscape patterns, and available resources in many ecosystems globally. The resulting fire regimes created complex fire-vegetation dynamics that were further influenced by biophysical setting, disturbance history, and climate. While there is increasing recognition of Indigenous fire stewardship among western scientists and managers, the extent and purpose of cultural burning is generally absent from the landscape-fire modeling literature and our understanding of ecosystem processes and development. In collaboration with the Karuk Tribe Department of Natural Resources, we developed a transdisciplinary Monte Carlo simulation model of cultural ignition location, frequency, and timing to simulate spatially explicit cultural ignitions across a 264,399-ha landscape within Karuk Aboriginal Territory in northern California. Estimates of cultural ignition parameters were developed with Tribal members and knowledge holders using existing interviews, historical maps, ethnographies, recent ecological studies, contemporary maps, and generational knowledge. Spatial and temporal attributes of cultural burning were explicitly tied to the ecology of specific cultural resources, fuel receptivity, seasonal movement patterns, and spiritual practices. Prior to colonization, cultural burning practices were extensive across the study landscape with an estimated 6972 annual ignitions, averaging approximately 6.5 ignitions per Indigenous fire steward per year. The ignition characteristics we document align closely with data on historical fire regimes and vegetation but differ substantially from the location and timing of contemporary ignitions. This work demonstrates the importance of cultural burning for developing and maintaining the ecosystems present at the time of colonization and underscores the need to work collaboratively with Indigenous communities to restore ecocultural processes in these systems.


Asunto(s)
Incendios , California , Conservación de los Recursos Naturales , Cultura , Ecosistema
4.
Nat Biotechnol ; 42(1): 132-138, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37231263

RESUMEN

We present avidity sequencing, a sequencing chemistry that separately optimizes the processes of stepping along a DNA template and that of identifying each nucleotide within the template. Nucleotide identification uses multivalent nucleotide ligands on dye-labeled cores to form polymerase-polymer-nucleotide complexes bound to clonal copies of DNA targets. These polymer-nucleotide substrates, termed avidites, decrease the required concentration of reporting nucleotides from micromolar to nanomolar and yield negligible dissociation rates. Avidity sequencing achieves high accuracy, with 96.2% and 85.4% of base calls having an average of one error per 1,000 and 10,000 base pairs, respectively. We show that the average error rate of avidity sequencing remained stable following a long homopolymer.


Asunto(s)
ADN , Nucleótidos , Nucleótidos/genética , Nucleótidos/química , ADN/genética , ADN/química , Replicación del ADN , Emparejamiento Base , Polímeros
5.
Cureus ; 15(11): e49318, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-38146548

RESUMEN

Metatarsal fractures are one of the most common injuries after foot trauma. It is debilitating, as the metatarsals are one of the most crucial bones for any weight-bearing movement. This report demonstrates the beneficial outcome of using Kirschner wires (K-wires) in a trauma setting and the complicated healing process. A 56-year-old gentleman was brought into the emergency department after a reinforced cement pipe fell onto the patient's steel-toe boots, striking his left foot immediately proximal to the steel portion of the boot. The patient had sustained displaced comminuted fractures of the left second, third, fourth, and fifth metatarsals with an extensive open wound (Gustilo type II open fracture). Open reduction with internal fixation (ORIF) was performed using K-wires to restore and preserve the anatomical and functional integrity of the foot. Following the surgery, the patient developed a hammer toe of the left fifth metatarsophalangeal (MTP) joint two months after the ORIF; we performed resection arthroplasty to relieve discomfort and further aid the recovery process. Following the resection arthroplasty, eschar had formed at the surgical site, extending from the lateral aspect of the left foot to the plantar surface, for which we had performed a skin graft after excisional debridement of the necrotic tissue. After one year of close follow-ups with rigorous physical therapy exercises, the patient had a fair recovery process and is now able to ambulate without any assistive devices. As such, using K-wires remains a viable option for reducing misaligned metatarsal fractures and providing fairly good outcomes even in the setting of severe foot trauma.

6.
J Burn Care Res ; 44(5): 1051-1061, 2023 09 07.
Artículo en Inglés | MEDLINE | ID: mdl-37423718

RESUMEN

The American Burn Association (ABA) hosted a Burn Care Strategic Quality Summit (SQS) in an ongoing effort to advance the quality of burn care. The goals of the SQS were to discuss and describe characteristics of quality burn care, identify goals for advancing burn care, and develop a roadmap to guide future endeavors while integrating current ABA quality programs. Forty multidisciplinary members attended the two-day event. Prior to the event, they participated in a pre-meeting webinar, reviewed relevant literature, and contemplated statements regarding their vision for improving burn care. At the in-person, professionally facilitated Summit in Chicago, Illinois, in June 2022, participants discussed various elements of quality burn care and shared ideas on future initiatives to advance burn care through small and large group interactive activities. Key outcomes of the SQS included burn-related definitions of quality care, avenues for integration of current ABA quality programs, goals for advancing quality efforts in burn care, and work streams with tasks for a roadmap to guide future burn care quality-related endeavors. Work streams included roadmap development, data strategy, quality program integration, and partners and stakeholders. This paper summarizes the goals and outcomes of the SQS and describes the status of established ABA quality programs as a launching point for futurework.


Asunto(s)
Quemaduras , Estados Unidos , Humanos , Quemaduras/terapia , Calidad de la Atención de Salud , Illinois , Predicción
7.
PhytoKeys ; 220: 83-108, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37251615

RESUMEN

Japanese knotweed (Reynoutriajaponica) is native to East Asia, but has been introduced to the West where it is a noxious invasive weed. Taxonomically, Japanese knotweed is placed within subtribe Reynoutriinae (Polygonaceae), which also contains the austral genus Muehlenbeckia (incl. Homalocladium) and north temperate Fallopia. In the current study, we conducted a phylogenetic analysis using sequence data from six markers, two nuclear (LEAFYi2, ITS) and four plastid (matK, rbcL, rps16-trnK and trnL-trnF) to further resolve the evolutionary relationships within this group, using the widest sampling of in-group taxa to date. The results of this analysis confirmed that subtribe Reynoutriinae is a monophyletic group, characterised by the presence of extra-floral, nectariferous glands at the base of leaf petioles. Within the subtribe, four main clades were identified: Reynoutria, Fallopiasect.Parogonum, Fallopia s.s. (including Fallopia sects. Fallopia and Sarmentosae) and Muehlenbeckia. The Fallopia s.s. and Muehlenbeckia clades are sister to one another, while the Fallopiasect.Parogonum clade is immediately basal to them and Reynoutria basal to all three. Fallopia, as currently circumscribed, is paraphyletic as Muehlenbeckia is nested within it. To resolve this, we propose that species of Fallopiasect.Parogonum should be treated as a new genus, Parogonum (Haraldson) Desjardins & J.P.Bailey, gen. et stat. nov. Within Reynoutria, the allied specific and infraspecific taxa that fall under the name Japanese knotweed s.l. form a monophyletic group and their taxonomic status is discussed.

8.
PLoS One ; 18(2): e0281927, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36848330

RESUMEN

As contemporary wildfire activity intensifies across the western United States, there is increasing recognition that a variety of forest management activities are necessary to restore ecosystem function and reduce wildfire hazard in dry forests. However, the pace and scale of current, active forest management is insufficient to address restoration needs. Managed wildfire and landscape-scale prescribed burns hold potential to achieve broad-scale goals but may not achieve desired outcomes where fire severity is too high or too low. To explore the potential for fire alone to restore dry forests, we developed a novel method to predict the range of fire severities most likely to restore historical forest basal area, density, and species composition in forests across eastern Oregon. First, we developed probabilistic tree mortality models for 24 species based on tree characteristics and remotely sensed fire severity from burned field plots. We applied these estimates to unburned stands in four national forests to predict post-fire conditions using multi-scale modeling in a Monte Carlo framework. We compared these results to historical reconstructions to identify fire severities with the highest restoration potential. Generally, we found basal area and density targets could be achieved by a relatively narrow range of moderate-severity fire (roughly 365-560 RdNBR). However, single fire events did not restore species composition in forests that were historically maintained by frequent, low-severity fire. Restorative fire severity ranges for stand basal area and density were strikingly similar for ponderosa pine (Pinus ponderosa) and dry mixed-conifer forests across a broad geographic range, in part due to relatively high fire tolerance of large grand (Abies grandis) and white fir (Abies concolor). Our results suggest historical forest conditions created by recurrent fire are not readily restored by single fires and landscapes have likely passed thresholds that preclude the effectiveness of managed wildfire alone as a restoration tool.


Asunto(s)
Incendios , Temperatura , Incendios Forestales , Ecosistema , Bosques , Noroeste de Estados Unidos , Pinus ponderosa
9.
J Burn Care Res ; 44(3): 535-545, 2023 05 02.
Artículo en Inglés | MEDLINE | ID: mdl-36752791

RESUMEN

Burn scars, and in particular, hypertrophic scars, are a challenging yet common outcome for survivors of burn injuries. In 2021, the American Burn Association brought together experts in burn care and research to discuss critical topics related to burns, including burn scars, at its State of the Science conference. Clinicians and researchers with burn scar expertise, as well as burn patients, industry representatives, and other interested stakeholders met to discuss issues related to burn scars and discuss priorities for future burn scar research. The various preventative strategies and treatment modalities currently utilized for burn scars were discussed, including relatively noninvasive therapies such as massage, compression, and silicone sheeting, as well as medical interventions such as corticosteroid injection and laser therapies. A common theme that emerged is that the efficacy of current therapies for specific patient populations is not clear, and further research is needed to improve upon these treatments and develop more effective strategies to suppress scar formation. This will necessitate quantitative analyses of outcomes and would benefit from creation of scar biobanks and shared data resources. In addition, outcomes of importance to patients, such as scar dyschromia, must be given greater attention by clinicians and researchers to improve overall quality of life in burn survivors. Herein we summarize the main topics of discussion from this meeting and offer recommendations for areas where further research and development are needed.


Asunto(s)
Quemaduras , Cicatriz Hipertrófica , Humanos , Informe de Investigación , Calidad de Vida , Quemaduras/complicaciones , Quemaduras/terapia , Cicatriz Hipertrófica/etiología , Cicatriz Hipertrófica/prevención & control , Geles de Silicona
10.
BJGP Open ; 6(4)2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36229069

RESUMEN

BACKGROUND: There are concerns about continuing increases in the number of patients prescribed long-term opioids and the prescribing of 'strong' opioids for chronic pain. Little is known about patients who are prescribed these long-term, high-dose drugs. AIM: To understand patterns of opioid prescribing that lead to long-term, high-dose use. DESIGN & SETTING: A mixed-method study of the opioid prescription histories of patients using high doses in a North Wales GP practice. METHOD: All patients on high-dose opioids during the census week were identified. Summary graphs of the prescription histories were prepared. Qualitative analysis was conducted individually by four researchers. A workshop was held to arrive at a consensus about common features and to inform further quantitative analysis. RESULTS: A quarter of high-dose regimens were initiated outside the practice, either in a different primary care practice or in secondary care. The majority of the remaining patients showed a pattern of dose increases to high levels over a short period (median 3.5 months). None showed a pattern of gradual increases over a longer timescale. Most of the patients remained on high doses continuously once a daily dose of ≥120 mg oral morphine equivalent (OME) was reached. CONCLUSION: These findings suggest that high-dose opioid regimens develop quickly in response to unknown clinical factors. An expected insidious upward drift in dose was not seen. The findings have implications for the prevention of potentially dangerous long-term, high-dose opioid prescribing. A dose of 60 mg OME or more is suggested as a useful 'red flag'.

11.
BJGP Open ; 6(4)2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36216370

RESUMEN

BACKGROUND: Prescribing of opioid medication has increased over the past 20 years. Most occurs in primary care for chronic pain. There is little evidence that these drugs are effective for this indication. There are concerns about the continuing prescribing of opioids, particularly in the long term and at high doses. AIM: To explore GPs' experiences of prescribing opioids, problems encountered, and factors militating against good prescribing practice. DESIGN & SETTING: Qualitative interviews with GPs who prescribe opioids in primary care in North East Wales. METHOD: Semi-structured interviews with 20 GPs were transcribed and subjected to thematic analysis utilising the framework approach. RESULTS: Participating GPs identified a range of problems associated with prescribed opioids. They were concerned about limited effectiveness of the drugs and what they perceived as addiction resulting from their use. They identified healthcare system factors that were obstacles to good prescribing practice such as lack of continuity of care, poor access to secondary care pain management support, and, most importantly, constant time pressure. They reported adverse effects on relationships with patients. Unrealistic expectations that pain could be eliminated resulted in pressure to prescribe stronger drugs and increased doses. It led to difficulties in establishing and maintaining trust and in persuading patients to agree to, and to carry out, dose reductions. CONCLUSION: Themes emerging from this study suggest that GPs lack appropriate control of opioid prescribing. There is a need to develop methods to help patients and GPs to work together to manage chronic pain safely.

12.
Vet Rec ; 191(3): 126, 2022 08.
Artículo en Inglés | MEDLINE | ID: mdl-35929717
13.
PLoS One ; 17(7): e0271370, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35802594

RESUMEN

[This corrects the article DOI: 10.1371/journal.pone.0261742.].

14.
BJGP Open ; 6(4)2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-35728819

RESUMEN

BACKGROUND: Opioid prescriptions for chronic pain have risen sharply over the last 25 years; harms associated with these drugs are related to dose and length of use. AIM: The main aim of this study was to identify patients prescribed long-term, high-dose (LTHD) opioids in the community and to assess the prevalence of such use. DESIGN & SETTING: An observational study of opioid prescribing in two demographically dissimilar GP practices in North Wales, UK. METHOD: Details of opioid prescriptions were collected for 22 841 patients, of whom 1488 (6.5%) were being prescribed opioids on the census date. Exhaustive examination of the data identified all patients who were prescribed oral morphine equivalent doses of ≥120 mg/day for ≥1 year. RESULTS: All these patients were being prescribed ≥120 mg/day, as a single drug, morphine, oxycodone, fentanyl, or buprenorphine, irrespective of opioid polypharmacy. Across both practices, 1.71/1000 patients were identified as LTHD users of opioid medication for chronic non-cancer pain (CNCP). Prevalence was similar in the two practices. Repetition of the process until January 2021 showed no change in the pattern. CONCLUSION: This study offers confirmation that a significant group of patients are prescribed long-term opioid medication for chronic pain at doses that are unlikely to be effective in reducing pain, but are likely to have harmful consequences. The findings offer a simple, reliable, and practical method of data extraction to identify these patients individually from routinely collected prescribing data, which will help in monitoring and treating individuals and establishing the problem prevalence.

15.
Nanotechnology ; 33(34)2022 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-35512668

RESUMEN

Radio frequency ablation and microwave hyperthermia are powerful tools for destroying dysfunctional biological tissues. However, wireless application of these techniques is hindered by their inability to focus the electromagnetic energy to small targets. The use of locally injected radio frequency- or microwave-absorbing nanomaterials can help to overcome this challenge by confining heat production to the injected region. Previous theoretical work suggests that high-aspect-ratio conducting nanomaterials, such as carbon nanotubes, offer powerful radio frequency and microwave absorption. While carbon nanotubes have been demonstrated as radiothermal agents, common solubilization methods may reduce their absorption efficiency, yielding undesirable nonspecific heating in the biological tissue background. In this manuscript, we hypothesize that pristine carbon nanotubes can act as efficient absorbers at radio frequencies, thus providing differential heating over the tissue background. Specifically, we use a sonication-free preparation technique to preserve both the high aspect ratio and local concentration of pristine carbon nanotubes. We validate the differential heating of these samples by 4.5-fold at 2 GHz compared to the heating of saline at a physiological concentration using infrared thermography. In addition, we successfully achieved local heating of pristine carbon nanotubes within a three-dimensional biological tissue phantom. Numerical simulations further aid in producing a temperature map within the phantom and confirming localized heating. Due to their significant differential and local heating, we believe that pristine carbon nanotubes may facilitate region-specific radio frequency ablation and microwave hyperthermia while keeping nonspecific heating to a low level in the normal tissue background.

16.
PLoS One ; 17(1): e0261742, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-34995300

RESUMEN

Extreme weather and globalisation leave our climate vulnerable to invasion by alien species, which have negative impacts on the economy, biodiversity, and ecosystem services. Rapid and accurate identification is key to the control of invasive alien species. However, visually similar species hinder conservation efforts, for example hybrids within the Japanese Knotweed complex.We applied the novel method of ATR-FTIR spectroscopy combined with chemometrics (mathematics applied to chemical data) to historic herbarium samples, taking 1580 spectra in total. Samples included five species from within the interbreeding Japanese Knotweed complex (including three varieties of Japanese Knotweed), six hybrids and five species from the wider Polygonaceae family. Spectral data from herbarium specimens were analysed with several chemometric techniques: support vector machines (SVM) for differentiation between plant types, supported by ploidy levels; principal component analysis loadings and spectral biomarkers to explore differences between the highly invasive Reynoutria japonica var. japonica and its non-invasive counterpart Reynoutria japonica var. compacta; hierarchical cluster analysis (HCA) to investigate the relationship between plants within the Polygonaceae family, of the Fallopia, Reynoutria, Rumex and Fagopyrum genera.ATR-FTIR spectroscopy coupled with SVM successfully differentiated between plant type, leaf surface and geographical location, even in herbarium samples of varying age. Differences between Reynoutria japonica var. japonica and Reynoutria japonica var. compacta included the presence of two polysaccharides, glucomannan and xyloglucan, at higher concentrations in Reynoutria japonica var. japonica than Reynoutria japonica var. compacta. HCA analysis indicated that potential genetic linkages are sometimes masked by environmental factors; an effect that can either be reduced or encouraged by altering the input parameters. Entering the absorbance values for key wavenumbers, previously highlighted by principal component analysis loadings, favours linkages in the resultant HCA dendrogram corresponding to expected genetic relationships, whilst environmental associations are encouraged using the spectral fingerprint region.The ability to distinguish between closely related interbreeding species and hybrids, based on their spectral signature, raises the possibility of using this approach for determining the origin of Japanese knotweed infestations in legal cases where the clonal nature of plants currently makes this difficult and for the targeted control of species and hybrids. These techniques also provide a new method for supporting biogeographical studies.


Asunto(s)
Especies Introducidas , Ploidias , Polygonaceae/clasificación , Polygonaceae/crecimiento & desarrollo , Polygonaceae/genética , Espectroscopía Infrarroja por Transformada de Fourier
17.
Br J Pain ; 15(3): 326-334, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34381614

RESUMEN

There has been a large increase in the number of prescriptions for opioid drugs in the United Kingdom over the last 20 years or more and the prescribing of opioids in high doses continues to increase. Much opioid prescribing is for chronic non-cancer pain (CNCP) despite serious doubts about the long-term effectiveness of opioids for this indication. Clinical experience is that there are increasing numbers of patients who are on high dosages of opioid drugs over sustained periods which provide limited or no pain relief while having significant negative effects on functioning and quality of life. The aim of this article is to bring readers' attention to some clinical observations of the CNCP population with high doses and to describe an intervention to reduce these doses. Many of these patients have no clinical features of addiction; we suggest that those who show little or no substance misuse behaviours are best understood as a distinct clinical population who have different treatment needs. In order to understand and treat these patients, a model is required which, rather than seeing the problem as lying solely with the patient, focuses on the interaction between the individual and his or her environment and seeks a change in what the patient does every day, rather than a simple, and largely unattainable, goal of symptom elimination. The clinician authors worked together to develop an intervention based upon approaches taken from both pain management and psychiatric practice. A detailed description of this rapid opioid reduction intervention (RORI) is provided along with some preliminary outcome data.

18.
Front Plant Sci ; 12: 640714, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34040619

RESUMEN

Double-cropping is defined as producing more than one crop on the same parcel of land in a single growing season. It is reported to have many benefits when incorporated in cropping systems, including improving soil health. In some double-cropping systems, soybean is planted following winter wheat. The soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) is a major soybean pathogen, and several reports suggest suppressive effects of wheat on SCN populations. Field trials were conducted from 2017 to 2018 to investigate the effect of wheat on SCN populations in double-cropping soybean. Nine fields with three levels of initial SCN populations (low, moderate, and high) were selected in Illinois. Wheat was planted in strips alternating with strips-maintained weed-free and under fallow over winter and early spring. Soybean was planted in all strips after wheat harvest. SCN egg densities were acquired at four time points: wheat establishment, post-wheat/pre-soybean, mid-soybean (R1 growth stage or beginning of flowering), and post-soybean harvest. Wheat strips reduced SCN egg densities compared with fallow strips at the R1 stage (-31.8%) and after soybean harvest (-32.7%). Double-cropping soybean with wheat has the potential to suppress SCN field populations and is a system with the potential to provide additional farm income. This study is meant to be a first step toward a better understanding of the mechanisms that govern the suppression of SCN by wheat.

19.
Appl Opt ; 60(3): 571-579, 2021 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-33690430

RESUMEN

The targeting task performance (TTP) model for prediction of target identification range suggests that boost filtering with a well-sampled, low-noise long-wave infrared (LWIR) sensor can substantially increase target ID range (by enhancing contrast at high spatial frequencies). We model a notional high-performance LWIR imaging system with a high F-number, deep electron wells, and a small-pitch focal plane array. System analysis performed with the Night Vision Integrated Performance Model (NVIPM) predicts that a range enhancement upwards of 50% is achievable with Wiener restoration applied to imagery from the modeled sensor. Human perception experiments were performed on simulated target imagery, with range through different boost filters (including a Wiener restoration filter) compared to the no-post-filter case. The TTP model was found to significantly overestimate the performance improvement due to boost and restoration filtering. Alternate predictions based on the Johnson criteria were also performed, and these underestimated the impact of boost. We speculate on reasons for the discrepancy and on promising avenues for future research. Sensor parameters, NVIPM predictions, filter parameters, and experimental data are provided.

20.
Rev Sci Instrum ; 91(12): 124705, 2020 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-33379935

RESUMEN

We present the development of a second generation digital readout system for photon counting microwave kinetic inductance detector (MKID) arrays operating in the optical and near-infrared wavelength bands. Our system retains much of the core signal processing architecture from the first generation system but with a significantly higher bandwidth, enabling the readout of kilopixel MKID arrays. Each set of readout boards is capable of reading out 1024 MKID pixels multiplexed over 2 GHz of bandwidth; two such units can be placed in parallel to read out a full 2048 pixel microwave feedline over a 4 GHz-8 GHz band. As in the first generation readout, our system is capable of identifying, analyzing, and recording photon detection events in real time with a time resolution of order a few microseconds. Here, we describe the hardware and firmware, and present an analysis of the noise properties of the system. We also present a novel algorithm for efficiently suppressing IQ mixer sidebands to below -30 dBc.

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