Extended depth of field for Fresnel zone aperture camera via fast passive depth estimation.

The lensless camera with incoherent illumination has gained significant research interest for its thin and flexible structure. However, it faces challenges in resolving scenes with a wide depth of field (DoF) due to its depth-dependent point spread function (PSF). In this paper, we present a single-shot method for extending the DoF in Fresnel zone aperture (FZA) cameras at visible wavelengths through passive depth estimation. The improved ternary search method is utilized to determine the depth of targets rapidly by evaluating the sharpness of the back propagation reconstruction. Based on the depth estimation results, a set of reconstructed images focused on targets at varying depths are derived from the encoded image. After that, the DoF is extended through focus stacking. The experimental results demonstrate an 8-fold increase compared with the calibrated DoF at 130 mm depth. Moreover, our depth estimation method is five times faster than the traversal method, while maintaining the same level of accuracy. The proposed method facilitates the development of lensless imaging in practical applications such as photography, microscopy, and surveillance.

High-precision detection method for an object edge based on a position-sensitive detector.

The paper proposed and verified a method of object edge detection based on the innovative defect spot working mode of the position-sensitive detector (PSD). With the output characteristics of the PSD in the defect spot mode and the size transformation properties of a focused beam, edge-detection sensitivity could be improved. Calibration experiments with the piezoelectric transducer (PZT) and object edge-detection experiments indicate that the object edge-detection sensitivity and accuracy of our method could reach 1 and 20 nm, respectively. Therefore, this method can be widely used in high-precision alignment, geometric parameters measurement, and other fields.

Detection and Classification of Cotton Foreign Fibers Based on Polarization Imaging and Improved YOLOv5.

It is important to detect and classify foreign fibers in cotton, especially white and transparent foreign fibers, to produce subsequent yarn and textile quality. There are some problems in the actual cotton foreign fiber removing process, such as some foreign fibers missing inspection, low recognition accuracy of small foreign fibers, and low detection speed. A polarization imaging device of cotton foreign fiber was constructed based on the difference in optical properties and polarization characteristics between cotton fibers. An object detection and classification algorithm based on an improved YOLOv5 was proposed to achieve small foreign fiber recognition and classification. The methods were as follows: (1) The lightweight network Shufflenetv2 with the Hard-Swish activation function was used as the backbone feature extraction network to improve the detection speed and reduce the model volume. (2) The PANet network connection of YOLOv5 was modified to obtain a fine-grained feature map to improve the detection accuracy for small targets. (3) A CA attention module was added to the YOLOv5 network to increase the weight of the useful features while suppressing the weight of invalid features to improve the detection accuracy of foreign fiber targets. Moreover, we conducted ablation experiments on the improved strategy. The model volume, mAP@0.5, mAP@0.5:0.95, and FPS of the improved YOLOv5 were up to 0.75 MB, 96.9%, 59.9%, and 385 f/s, respectively, compared to YOLOv5, and the improved YOLOv5 increased by 1.03%, 7.13%, and 126.47%, respectively, which proves that the method can be applied to the vision system of an actual production line for cotton foreign fiber detection.

Compact multispectral photodetectors based on nanodisk arrays atop optical cavity substrates.

It is challenging for the multi-spectral photodetector to have a compact structure, high spectral resolution, and high detection efficiency. This paper reports on a new approach for compact multi-spectral visible light detecting based on the hexagonal lattice silver nanodisk arrays atop optical cavity substrates. Through numerical calculations and optimizations of experiments, we verified that the narrow band responsivity of the photodetector was caused by coupling the surface plasmonic resonances and cavity mode. The multi-spectral photodetector exhibited that the minimum FWHM and the maximum responsivity of was achieved to be 80 nm and 91.5 mA·W-1, respectively. Besides, we also analyzed the influence of the proposed structure on the energy wastage by numerical comparison. The proposed way for multi-spectral photodetector is promising to be an excellent design for the narrow band spectral detection. The design can also be easily integrated with CMOS devices and applied to other spectral regimes for different applications.

Temporal behavior of the high-power pulsed gas terahertz laser pumped by a fundamental mode TEA CO2 laser.

Optically pumped gas molecular terahertz (THz) lasers are promising for generating high-power and high-beam-quality coherent THz radiation. However, for pulsed gas THz lasers, the temporal behavior of the output THz pulse has rarely been investigated. In this study, the temporal behavior of a pulsed gas THz pumped by a fundamental-mode TEA CO2 laser has been presented for the first time both in simulation and experiment. A modified laser kinetics model based on the density matrix rate equation was used to simulate the temporal behavior and output pulse energy of a pulsed gas THz laser at different gas pressures. The results clearly show that the working gas pressure and pump pulse energy have critical influences on the output THz pulse shape. Three typical pulse shapes were obtained, and the THz pulse splitting caused by gain switching was quantitatively simulated and explained based on the laser dynamic process. Besides, with an incident pump pulse energy of 342 mJ, the maximum output THz pulse energy of 2.31 mJ was obtained at 385 µm, which corresponds to a photon conversion efficiency of approximately 56.1%, and to our knowledge, this is the highest efficiency for D2O gas THz laser. The experimental results agreed well with those of the numerical simulation for the entire working gas pressure range, indicating that our model is a powerful tool and paves the way for designing and optimizing high-power pulsed gas lasers.

Random color filters based on an all-dielectric metasurface for compact hyperspectral imaging.

Metasurface filters are a compact, lightweight, and inexpensive solution for the miniaturized hyperspectral imaging system. However, the emerging applicability of these filters is limited by the trade-off between spatial and spectral resolutions. In this study, we establish and experimentally demonstrate a compact hyperspectral photodetection method using random all-dielectric metasurface filters that are directly integrated on the detectors. Based on compressive sensing algorithms, the compact photodetectors can accurately reconstruct the incident spectrum in the visible range. The minimum full width at half maximum (FWHM) of the spectrum reconstructed is 4.8 nm, which fully satisfies the requirements of hyperspectral imaging. The proposed method may be applied in the design, development, and measurement of compact hyperspectral imaging systems.

Unidirectional coupling and efficient detection of near-infrared surface plasmon polaritons for on-chip optoelectronic interconnection.

Plasmonic interconnection is one kind of the possible methods to construct next-generation optoelectronic integrated circuits. In this paper, the plasmonic interconnection device based on Ge in infrared band is constructed, through efficient electron-hole pair generation, the device can achieve high photocurrent response (0.25A/W). Because of the low plasmon coupling efficiency of the conventional basic periodic gratings, this paper optimized the design of the coupling structure and improved the coupling efficiency by 4 times through constructing a binary Bragg/periodic grating coupler which can realize unidirectional plasmon coupling with a simulated extinction ratio of 12.5 dB. The devices can be easily fabricated by single-step electron beam lithography and lift-off process. The experimental results verified a 3.5 times improvement in the SPPs current of the designed plasmonic interconnection device, which provides a technical path to realize efficient plasmon transmission and detection for on-chip optoelectronic interconnection.

Rural, urban, and suburban differences in influenza vaccination coverage among children.

Influenza vaccination is the primary way to prevent influenza, yet influenza vaccination coverage remains low in the United States. Previous studies have shown that children residing in rural areas have less access to healthcare and lower vaccination coverage for some vaccines. Influenza vaccination coverage among children 6 months-17 years by rural/urban residence during the 2011-12 through 2018-19 influenza seasons was examined using National Immunization Survey-Flu data. The Council of American Survey Research Organizations response rates for National Immunization Survey-Flu ranged from 48% to 65% (2011-12 through the 2017-18 seasons) for the landline sample and 20%-39% (2011-12 through the 2018-19 seasons) for the cellular telephone sample. Children residing in rural areas had influenza vaccination coverage that ranged from 7.9 (2012-13 season) to 12.6 (2016-17 season) percentage points lower than children residing in urban areas, and ranged from 4.5 (2012-13 season) to 7.4 (2016-17 season) percentage points lower than children residing in suburban areas. The differences in influenza vaccination coverage among rural, suburban, and urban children were consistent over the eight seasons studied. Lower influenza vaccination coverage was observed among rural children regardless of child's age, mother's education, household income, or number of children under 18 years of age in the household. Rural versus urban and suburban differences in influenza vaccination coverage remained statistically significant while adjusting for selected sociodemographic characteristics. A better understanding of the reasons for lower childhood influenza vaccination coverage for children in rural and suburban areas is needed.

Trends in Childhood Influenza Vaccination Coverage, United States, 2012-2019.

OBJECTIVE: The objective was to compare estimates of childhood influenza vaccination across 7 consecutive influenza seasons based on 2 survey systems. METHODS: We analyzed data from the National Health Interview Survey (NHIS) and the National Immunization Survey-Flu (NIS-Flu) using Kaplan-Meier survival analysis to estimate receipt, based on parental report, of at least 1 dose of influenza vaccine among children aged 6 months to 17 years. RESULTS: We found no significant increasing trend in influenza vaccination coverage among children overall from 2012 to 2018 based on the NHIS or from 2012 to 2019 based on the NIS-Flu. We found 4 seasons with a significant increase in influenza vaccination coverage compared with the previous season (2012-2013 [NHIS, NIS-Flu], 2013-2014 [NIS-Flu], 2017-2018 [NHIS], and 2018-2019 [NIS-Flu]). As of the 2018-2019 season, based on NIS-Flu, influenza vaccination coverage was only 62.6%. Children with health conditions that put them at increased risk for complications from influenza had higher influenza vaccination coverage than children without these health conditions for all the seasons studied except 2014-2015. For all seasons studied, influenza vaccination coverage estimates for children were higher based on NIS-Flu data compared with NHIS data. Trends across seasons and differences in vaccination coverage between age groups were similar between the 2 surveys. CONCLUSIONS: Influenza vaccination coverage among children appears to have plateaued. Only about half of the children in the United States were vaccinated against influenza. Improvements in measurement of influenza vaccination and development and review of strategies to increase childhood influenza vaccination coverage are needed.

In situ interface engineering for probing the limit of quantum dot photovoltaic devices.

Quantum dot (QD) photovoltaic devices are attractive for their low-cost synthesis, tunable band gap and potentially high power conversion efficiency (PCE). However, the experimentally achieved efficiency to date remains far from ideal. Here, we report an in-situ fabrication and investigation of single TiO2-nanowire/CdSe-QD heterojunction solar cell (QDHSC) using a custom-designed photoelectric transmission electron microscope (TEM) holder. A mobile counter electrode is used to precisely tune the interface area for in situ photoelectrical measurements, which reveals a strong interface area dependent PCE. Theoretical simulations show that the simplified single nanowire solar cell structure can minimize the interface area and associated charge scattering to enable an efficient charge collection. Additionally, the optical antenna effect of nanowire-based QDHSCs can further enhance the absorption and boost the PCE. This study establishes a robust 'nanolab' platform in a TEM for in situ photoelectrical studies and provides valuable insight into the interfacial effects in nanoscale solar cells.

Large-scale, broadband absorber based on three-dimensional aluminum nanospike arrays substrate for surface plasmon induced hot electrons photodetection.

Performance of plamson induced hot electrons-based photodetectors largely relies on the photon absorption capability. To improve the optical absorption, many perfect absorbers based on the periodic metallic nanostructures have been designed and fabricated through low-throughput, costly and time-consuming lithographic processes, which seriously limit the future potential applications of plasmonic hot electrons optoelectronics devices. Here, a large-scale, broadband absorber consisting of ITO film, ZnO layer, Au film and Al nanospike array substrate was designed and fabricated for hot electrons-based photodetection. The new designed absorber's absorptivity can be up to 70% in the broad wavelength range from 400 nm to 800 nm (even up to 90% in the wavelength range from 400-550 nm) and most of the absorption comes from the Au film, which is effective for the generation of hot electrons. The enhanced broadband absorption is ascribed to the surface plasmon polariton mode and localized surface plasmon resonance mode supported by the nanospike arrays. The influence of geometry and material parameters on the optical absorption properties is also specifically investigated through numerical simulation. The efficient and broadband absorption of a nanospikes device results in a much larger photocurrent compared with that of a planar reference device. Our approach, which is compatible with large-scale manufacturing, paves the way for the practical implementation of hot electrons-based optoelectronic devices.

Association between patient reminders and influenza vaccination status among children.

BACKGROUND: Patient reminders are recommended to increase vaccination rates. The objectives of this study were to estimate the percentage of children 6 months-17 years for whom a patient reminder for influenza vaccination was received by a child's parent or guardian, estimate influenza vaccination coverage by receipt of a patient reminder, and identify factors associated with receipt of a patient reminder. METHODS: National Immunization Survey-Flu (NIS-Flu) data for the 2013-14 influenza season were analyzed. Tests of association between patient reminders and demographic characteristics were conducted using Wald chi-square tests and pairwise comparison t-tests. Multivariable logistic regression was used to determine variables independently associated with receiving a patient reminder. RESULTS: Approximately 22% of children had a parent or guardian report receiving a patient reminder for influenza vaccination for their child, ranging from 12.9% in Idaho to 41.2% in Mississippi. Children with a patient reminder were more likely to be vaccinated compared with children without a patient reminder (73.7% versus 55.5%). In the multivariable model, reminder receipt was higher for children 6-23 months compared with children 13-17 years, black children compared with white children, and children whose parent completed the survey in English compared with children whose parent completed the survey in a language other than English or Spanish. CONCLUSIONS: Although patient reminders are associated with a higher likelihood of influenza vaccination, nationally, less than one-fourth of children had a parent report receiving one. Despite being based on parental report, with its limitations, this study suggests that increasing the number of parents who receive patient reminders for their children may improve vaccination coverage among children.

Paid sick leave benefits, influenza vaccination, and taking sick days due to influenza-like illness among U.S. workers.

INTRODUCTION: Staying home when sick can reduce the spread of influenza. The objectives of this study were to quantify the percentage of workers who had paid sick leave (PSL) benefits, examine sociodemographic characteristics that may be associated with having these benefits, and examine the association between having PSL benefits and use of sick days and influenza vaccination status. METHODS: The public-use dataset from the 2009 National H1N1 Flu Survey (NHFS) were analyzed in 2017. Wald chi-square tests and t-tests were used to test for associations between having PSL benefits and sociodemographic characteristics and industry and occupation groups, the associations between having PSL benefits and seeking treatment when sick with influenza-like illness (ILI), and taking days off work when sick with ILI. Logistic regression was used to determine variables associated with having PSL benefits and the association between having PSL benefits and influenza vaccination status. RESULTS: Sixty-one percent of employed adults reported having PSL benefits during the 2009-10 influenza season. Being younger, female, Hispanic, less educated, or a farm/blue collar worker were associated with reduced likelihood of having PSL benefits. Not having PSL benefits was associated with a lower likelihood of receiving an influenza vaccination and visiting a health professional when sick with ILI. CONCLUSIONS: The percentage of workers who have PSL benefits differs by sociodemographic characteristics and industry/occupation groups. Offering PSL benefits along with promoting influenza vaccination and encouraging employees with ILI to stay home can increase influenza vaccination coverage and help control the spread of influenza.

Association between provider recommendation and influenza vaccination status among children.

BACKGROUND: Provider recommendation is associated with influenza vaccination receipt. The objectives of this study were to estimate the percentage of children 6 months-17 years for whom a provider recommendation for influenza vaccination was received, identify factors associated with receipt of provider recommendation, and evaluate the association between provider recommendation and influenza vaccination status among children. METHODS: National Immunization Survey-Flu (NIS-Flu) parentally reported data for the 2013-14, 2014-15, and 2015-16 seasons were analyzed. Tests of association between provider recommendation and demographic characteristics were conducted using Wald chi-square tests and pairwise comparison t-tests. Multivariable logistic regression was used to determine variables independently associated with receiving provider recommendation and the association between provider recommendation and influenza vaccination status. RESULTS: Approximately 70% of children had a parent report receiving a provider recommendation for influenza vaccination for their child. The strongest association between receipt of provider recommendation and demographic characteristics was with child's age, with younger children (6-23 months, 2-4 years, and 5-12 years) being more likely to have a provider recommendation than older children (13-17 years). In addition, children living in a household above poverty with household income >$75,000 were more likely to have a parent report receipt of a provider recommendation than children living below poverty. Children with a provider recommendation were twice as likely to be vaccinated than those without. CONCLUSIONS: This study affirms the importance of provider recommendation for influenza vaccination among children. Ensuring that parents of all children receive a provider recommendation may improve vaccination coverage.

Au nanoparticle-decorated silicon pyramids for plasmon-enhanced hot electron near-infrared photodetection.

The heterojunction between metal and silicon (Si) is an attractive route to extend the response of Si-based photodiodes into the near-infrared (NIR) region, so-called Schottky barrier diodes. Photons absorbed into a metallic nanostructure excite the surface plasmon resonances (SPRs), which can be damped non-radiatively through the creation of hot electrons. Unfortunately, the quantum efficiency of hot electron detectors remains low due to low optical absorption and poor electron injection efficiency. In this study, we propose an efficient and low-cost plasmonic hot electron NIR photodetector based on a Au nanoparticle (Au NP)-decorated Si pyramid Schottky junction. The large-area and lithography-free photodetector is realized by using an anisotropic chemical wet etching and rapid thermal annealing (RTA) of a thin Au film. We experimentally demonstrate that these hot electron detectors have broad photoresponsivity spectra in the NIR region of 1200-1475 nm, with a low dark current on the order of 10-5 A cm-2. The observed responsivities enable these devices to be competitive with other reported Si-based NIR hot electron photodetectors using perfectly periodic nanostructures. The improved performance is attributed to the pyramid surface which can enhance light trapping and the localized electric field, and the nano-sized Au NPs which are beneficial for the tunneling of hot electrons. The simple and large-area preparation processes make them suitable for large-scale thermophotovoltaic cell and low-cost NIR detection applications.

Wet Chemical Synthesis of Silica Nanosheets via Ethyl Acetate-Mediated Hydrolysis of Silica Precursors and Their Applications.

Freestanding and transferable silica nanosheets with thicknesses of ≈5-7 nm are prepared via ethyl acetate-mediated hydrolysis of silica precursors in aqueous solution. The resulting silica nanosheets have shown many potential applications. For example, they can be used as the support film on the finer mesh grids for transmission electron microscopy imaging and as the precursor for the synthesis of silicon nanosheets.

Parental-Reported Full Influenza Vaccination Coverage of Children in the U.S.

INTRODUCTION: Depending upon influenza vaccination history, children aged 6 months-8 years need one or two doses of influenza vaccine to be considered fully vaccinated. The objectives of this study were to quantify the percentage of children aged 6 months-8 years who were fully vaccinated against influenza based on parental report, overall, by state, and by sociodemographic characteristics, and to examine sociodemographic characteristics associated with being fully vaccinated. METHODS: Data from the National Immunization Survey-Flu for the 2012-2013 and 2013-2014 influenza seasons were analyzed in 2015 using the Kaplan-Meier method to produce vaccination coverage estimates. Wald chi-square tests were used to test for bivariate associations, and Cox proportional hazards models were used to test for demographic characteristics independently associated with the child being fully vaccinated. RESULTS: The percentages of children aged 6 months-8 years who were fully vaccinated during the 2012-2013 and 2013-2014 influenza seasons were 41.0% and 45.2%, respectively. Full vaccination varied widely by state and was more likely for children requiring only one dose. Based on the statistical models, children likely to be fully vaccinated were older, non-black, had a mother with an education >12 years, or lived in a high-income household. CONCLUSIONS: Most children in the U.S. are not fully vaccinated against influenza. Reminder systems and interventions that reduce or remove barriers to children receiving their second doses of influenza vaccine may improve full influenza vaccination coverage among all children.

Efficacy of Quetiapine Monotherapy in Posttraumatic Stress Disorder: A Randomized, Placebo-Controlled Trial.

OBJECTIVE: This was a 12-week randomized, placebo-controlled trial to assess the efficacy of quetiapine monotherapy in the treatment of posttraumatic stress disorder (PTSD). METHOD: Eighty patients were randomly assigned to treatment with either quetiapine or placebo. The primary outcome measure was the Clinician-Administered PTSD Scale (CAPS). Secondary efficacy measures included the CAPS subscales, the Davidson Trauma Scale, the Positive and Negative Syndrome Scale (PANSS), the Clinical Global Impressions (CGI) scales for severity of Illness and improvement, the Hamilton Depression Rating Scale (HAM-D), and the Hamilton Anxiety Rating Scale (HAM-A). Safety measurements included adverse events, vital signs, the Abnormal Involuntary Movement Scale, the Barnes Akathisia Scale, the Simpson-Angus Scale, and the Arizona Sexual Experiences Scale. RESULTS: After a 1-week placebo run-in, quetiapine was started at a daily dosage of 25 mg and increased to a maximum of 800 mg; the average was 258 mg (range, 50-800 mg). Reductions in CAPS total, re-experiencing, and hyperarousal scores were significantly greater for the quetiapine group than for the placebo group. Greater improvements were also observed for quetiapine in scores on the Davidson Trauma Scale, CGI severity and improvement ratings, PANSS positive symptom and general psychopathology subscales, HAM-A, and HAM-D than for placebo. Adverse events were generally mild and expected based on prior studies of quetiapine in this and other patient population. There were no differences in safety measures between groups. CONCLUSION: Quetiapine monotherapy was efficacious in the treatment of PTSD. These findings suggest quetiapine as a single agent is effective in treating military PTSD.

Place of influenza vaccination among children--United States, 2010-11 through 2013-14 influenza seasons.

BACKGROUND: Studies are published on settings adults receive influenza vaccination but few have reported on settings children are vaccinated and how this might be changing over time or vary by socio-demographics. METHODS: Data from the National Immunization Survey-Flu were analyzed to assess place of influenza vaccination among vaccinated children 6 months-17 years during the 2010-11, 2011-12, 2012-13, and 2013-14 influenza seasons. The percentage of children vaccinated at each place was calculated overall and by age, race/ethnicity, income, and Metropolitan Statistical Area (MSA). RESULTS: The places children received influenza vaccination varied little over four recent influenza seasons. From the 2010-11 through 2013-14 influenza seasons the percentage of vaccinated children receiving influenza vaccination at a doctor's office was 64.1%, 65.1%, 65.3%, and 65.3%, respectively with no differences from one season to the next. Likewise, for vaccination at clinics or health centers (17.8%, 17.5%, 17.0%. 18.0%), health departments (3.2%, 3.6%, 3.0%, 2.8%), and other non-medical places (1.6%, 1.4%, 1.2%, 1.1%), there were no differences from one season to the next. There were some differences for vaccinations at hospitals, pharmacies, and schools. There was considerable variability in the place of influenza vaccination by age, race/ethnicity, income, and MSA. Fewer Hispanic children were vaccinated at a doctor's office than black, white, and other or multiple race children and fewer black children and children of other or multiple races were vaccinated at a doctor's office than white children. More children at or below the poverty level were vaccinated at a clinic or health center than all of the other income groups. CONCLUSION: Most vaccinated children receive their influenza vaccination at a doctor's office. Place of vaccination changed little over four recent influenza seasons. Large variability in place of vaccination exists by age, race/ethnicity, income, and MSA. Monitoring place of vaccination can help shape future immunization programs.

Complete Influenza Vaccination Trends for Children Six to Twenty-Three Months.

OBJECTIVE: Prevention of influenza among infants and young children is a public health priority because of their high risk for influenza-related complications. Depending on a child's age and previous influenza vaccination history, they are recommended to receive either 1 dose or 2 doses of influenza vaccine to be considered fully vaccinated against influenza for the season. We compared estimates of full (complete) influenza vaccination coverage of children 6 to 23 months across 10 consecutive influenza seasons (2002-2012), by race/ethnicity, age group, and by number of doses required to be fully vaccinated given child's vaccination history. METHODS: National Immunization Survey data were used to estimate full influenza vaccination status among children 6 to 23 months on the basis of provider report. Estimates were computed by using Kaplan-Meier survival analysis methods. RESULTS: Full influenza vaccination coverage among children 6 to 23 months increased from 4.8% in the 2002-2003 influenza season to 44.7% in the 2011-2012 season. In all 10 influenza seasons studied, non-Hispanic black children and Hispanic children had lower full influenza vaccination coverage than non-Hispanic white children. For all 10 influenza seasons, full influenza vaccination coverage was higher among children requiring only 1 dose compared with those requiring 2 doses. CONCLUSIONS: Less than half of children 6 to 23 months in the United States, and an even a smaller percentage of Hispanic and non-Hispanic black children, are fully vaccinated against influenza. More implementation of evidence-based strategies that increase the percentage of children who are fully vaccinated is needed.