bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultra-pixel precision correction method for maskless lithography projection distortion
Authors: Huang Long , Liu Yu-Qing , Zhao Shaoqing , Cong Yuxuan , Zhou Dechun , Zhang Liu , Dong Yongjun , Liu Hua
Published: September 2024

Distortion is a common issue in projection lens imaging, leading to image distortion and edge deformation, which significantly affects the quality of the projected pattern. Conventional methods for distortion correction are typically constrained by the precision of the projection pixel size. In this work, we propose an ultra-pixel precision correction method for projection distortion in projection lithography systems. By fitting the position error between the projected pattern and the calibration pattern, and combining the overlapping lithography method with the digital correction method to reduce quantization error, we have overcome the limitation of pixel size on correction precision, thereby achieving ultra-pixel precision calibration of the projected pattern. The resulting position error of the final exposed pattern can be reduced to approximately 1µm (with a projection pixel side length of 5.4µm). The zone plate fabricated using this method exhibits extremely high ring band position accuracy, and the diffraction test patterns are highly consistent with the simulation results. Our ultra-pixel precision correction method, based on a calibration substrate, is characterized by its simplicity of operation, cost-effectiveness, and wide adaptability. It plays a pivotal role in enhancing the quality of lithographic patterns within lithography systems.
Research on polarization effect suppression method of weak starlight simulation device
Authors: Wu Linghao , Wang Jiaan , Sheng Lan , Li Yihuan , Xia Yuxin , Zhang Siqi , Gu Siwen
Published: September 2024

Under the influence of the polarization effect, the background stray light of the weak starlight simulator and the polarization state of the simulated target star point are doped with each other, so it is difficult to achieve accurate suppression of polarized stray light. In this paper, the mechanism of background stray light induced by the optical engine in a weak starlight simulation device is analyzed, and the principle of mutual doping between stray light and simulated target starlight polarization state is studied. The correlation model of polarization parameters, point source transmittal, and simulated target magnitude was established, and the optimization process of polarization effect was constructed to achieve accurate suppression of polarized stray light in the star map background. The simulation results show that after the optimization of the optical engine, the maximum point source transmittivity is 6.084 × 10−6, which meets the 6-magnitude star accurate recognition threshold. The experimental results show that the stray light suppression ability of the weak starlight simulation device is improved by nearly 2 times, and the magnitude simulation accuracy is improved by 1.8 times.
Micro-integrated crossed-beam optical dipole trap system with long-term alignment stability for mobile atomic quantum technologies
Authors: Christ Marc , Anton Oliver , Zimmermann Conrad , Henderson Victoria A , Da Ros Elisa , Krutzik Markus
Published: September 2024

Quantum technologies extensively use laser light for state preparation, manipulation, and readout. For field applications, these systems must be robust and compact, driving the need for miniaturized and highly stable optical setups and system integration. In this work, we present a micro-integrated crossed-beam optical dipole trap setup, the µXODT, designed for trapping and cooling 87Rb. This fiber-coupled setup operates at 1064 nm wavelength with up to 2.5 W optical power and realizes a free-space crossed beam geometry. The µXODT precisely overlaps two focused beams (w0 ≈ 33 µm) at their waists in a 45° crossing angle, achieving a position difference of ≤3.4 µm and a 0.998 power ratio between both beams with long-term stability. We describe the design and assembly process in detail, along with optical and thermal tests with temperatures of up to 65 °C. The system’s volume of 25 ml represents a reduction of more than two orders of magnitude compared to typically used macroscopic setups while demonstrating exceptional mechanical robustness and thermal stability. The µXODT is integrated with an 87Rb 3D MOT setup, trapping 3 × 105 atoms from a laser-cooled atomic cloud, and has shown no signs of degradation after two years of operation.
Electro-optic frequency comb generation via cascaded modulators driven at lower frequency harmonics
Authors: Eliason Todd , Parker Payton A. , Reber Melanie A. R.
Published: September 2024

Electro-optical modulation of a continuous wave laser is a highly stable way to generate frequency combs, gaining popularity in telecommunication and spectroscopic applications. These combs are generated by modulating non-linear electro-optic crystals with radio frequencies, creating equally spaced side-bands centered around the single-frequency seed laser. Electro-optic frequency comb architectures often choose between optical bandwidth (cascaded GHz combs) or higher mode density (chirped RF generation). This work demonstrates an electro-optic frequency comb with > 120 GHz of bandwidth and an 80 MHz repetition rate. The comb has three cascaded electro-optic modulators driven at sequentially lower harmonics, the last megahertz modulation dictating the repetition rate. This architecture can modulate at any individual harmonic and repetition rate without changes to the components. This comb can be used in any applications where a stable and tunable repetition rate is needed.
Tip tilt and focus estimation based on LGS and downlink joint measurements for ground to GEO satellite optical communication link
Authors: Lognoné Perrine , Rekaya Ghaya , Montmerle-Bonnefois Aurélie , Paillier Laurie , Conan Jean-Marc
Published: September 2024

Achieving high data rates in GEO Feeder optical uplinks faces challenges due to the fading nature of the channel induced by atmospheric turbulence. Adaptive optics pre-compensation using downlink measurements is a solution to mitigate the impact of the turbulence. However, the point-ahead angle anisoplanatism, inherent to the bidirectional link geometry, limits the uplink correction efficiency, leading to persistent signal fades and loss of information onboard the satellite. We recently proposed a new minimum mean square error method that improves the phase estimation at the PAA based on the downlink phase and log amplitude measurements, reducing the anisoplanatism impact on the coupled flux. Alternatively, a laser guide star can be used to measure the phase at the PAA. However, it is currently challenging to retrieve the tip, tilt, and focus modes, whose correction is essential to improve the link quality. In this article, we propose to combine both techniques to estimate the tip, tilt, and focus at the PAA by incorporating the LGS high-order measurements in the MMSE formalism. We develop the associated analytical reconstructor and evaluate the performance of the phase estimation and the gain on the coupled flux statistics aboard the GEO satellite, considering an idealized LGS system. The new estimator is shown to reduce the tip, tilt, and focus error variances by up to 70% of their initial value.
Formation and conversion of high-peak-power structured beams by an Nd:YVO4/Cr4+:YAG laser subject to tight-focusing off-axis pumping
Authors: Tuan Pi-Hui , Peng Bo-Xiang , Liu Shu-Cheng , Cheng Yu-Zhe
Published: September 2024

A compact Nd:YVO4/Cr4+:YAG passively Q-switched laser in a near-hemispherical resonator is exploited to realize high-peak-power pulsed beams with high spatial degrees of freedom. Beneficial from the advantages of strong intracavity beam focusing as well as the point-like excitation condition for the proposed cavity design, various high-order structured pulses as coherent superpositions of multiple degenerate eigenmodes are stably generated under different off-axis pump schemes. Besides, by employing external-cavity astigmatic mode conversion (AMC), the oval-shaped and chessboard-like structured pulses under on-axis and 1D off-axis pumping are transformed into exotic modes with polygonal and figure-eight-shaped envelopes to further enrich the spatial complexity of the generated fields. With well-defined beam structures that are reconstructed using the analytical resonant wave functions of the resonator, the phase structures of AMC pulsed fields are numerically resolved to present a variety of singularity arrays. Experimental results reveal that the overall peak power of the on-axis and off-axis generated structured pulses respectively exceeds 600 W and 1 kW while maintaining good pulse train stability with peak-to-peak amplitude fluctuation to be less than 10% and 15%.
Magnetic beads-water suspension: a green material for nonlinear optical limiting
Authors: Dong Biao , Lu Yuangang , Huang Jian , Liu Yang , He Chongjun
Published: September 2024

The development of environmentally friendly and reusable suspensions remains a challenge to explore new nonlinear optical limiting (NOL) materials. In this paper, we innovatively propose and prepare magnetic beads (MBs) suspension as a “green” material for nonlinear optical limiting, in which water is used as an environmentally friendly solvent and MBs are used as easily recyclable and reusable solutes. Low-cost, easily dispersed, highly stable, and recyclable MBs with different diameters (∼200 nm, ∼300 nm, and ∼400 nm) are synthesized by a facile one-step method using Sodium Citrate, NaOH, NaNO3, and FeSO4·4H2O. Then, magnetic beads-water (MBs-water) suspension is obtained by dispersing MBs in water for use in NOL. The MBs in the suspension can be removed from the water by an external magnetic field after being used for NOL purposes, and are recycled and reused. Therefore, this interesting characteristic makes the MBs-water suspension what we believe to be a novel green NOL material. The experimental results of NOL show that MBs-water suspensions have a high NOL capacity at the wavelength of 1064 nm. MBs-water suspensions with a concentration of 0.046 mg/mL exhibit excellent NOL performance with a maximum NOL capability value of 0.53 and a minimum transmittance value of 0.23. The light scattering measurement of the MBs-water suspension shows that the scattering intensities increase significantly along with the decrease of transmission, indicating that nonlinear scattering is responsible for optical limiting. Excellent characteristics of environmental friendliness, easy preparation, recyclability, and high NOL capacity make the green MBs-water suspension a promising candidate for NOL applications.
Flexible focal array engineering with a binary array vector optical field
Authors: Gao Xu-Zhen , Li Qing-Lu , Zhao Tian-Fei , Kong Ya-Ning , Tan Guo-Dong , Pan Yue
Published: September 2024

In recent years, the vector optical field (VOF) with space-variant polarization distribution has attracted great attention due to its unexpected effects and applications in a wide range of areas. The focal engineering plays the most important role, as the focused VOF provides various interesting properties. Here, we propose a kind of binary array VOF (BA-VOF), which can be applied in focal array engineering. The BA-VOF comprises an array of the first base field of radially polarized VOF and an array of the second base field of superposed subfields with phase modulations. We theoretically design and experimentally generate the BA-VOF. Based on the BA-VOF, we present a flexible method to manipulate the amount of the focal spots in the focal array. Moreover, the polarization state and spin angular momentum of each focal spot in the focal spot array can also be flexibly manipulated. The BA-VOF and the flexibly manipulated focal array are inspirable in the area of structured light, which can be applied in regions needing focal engineering, such as optical tweezers, optical fabrication, optical imaging, and so on.
Boosting pulse characterization precision for Ho: YAP double pulse laser with back propagation neural network
Authors: Li Kuan , Niu Chao , Shen Yuzhuo , Lu Qi , Wu Chunting , Yu Yongji
Published: September 2024

The precise energy and temporal control advantages of the 2 µm double-pulse laser have diverse applications in laser processing, biomedicine, and communications. The Ho: YAP Q-switched double pulse laser, a complex system, demands comprehensive theoretical analysis and precise experimental operations, especially when managing pulse overlap and ensuring output stability. Traditional design methods, time-consuming and labor-intensive, pose challenges in error elimination and susceptibility to environmental and device instabilities. This paper focuses on regulating the design and performance of the Ho: YAP Q-switched double-pulse laser. Critical developmental and optimization challenges are addressed by utilizing a back propagation neural network to forecast the nonlinear propagation of the laser while affirming the feasibility of bypassing intricate numerical solution models. This strategy streamlines experimental trials, ensuring reliable predictions of laser output characteristics and laying the foundation for forecasting more intricate laser systems in the future.
Pair-OAM properties in scalar light beams
Authors: Martinez Sebastian , Pokharel Sushil , Korotkova Olga
Published: September 2024

We reveal the geometric structure existing on segregation of a pair of orbital angular momentum (OAM) states from the total random light beam and introduce new quantities, to the best of our knowledge, for its characterization. In particular, the degree and the ellipse of orbitalization are introduced in analogy with those in the polarization theory. Free-space propagation of these quantities is illustrated by numerical examples. The limiting case of a deterministic light beam is also separately discussed.
Si-waveguide-based optical power monitoring of a 2 × 2 Mach–Zehnder interferometer based on a InGaAsP/Si hybrid MOS optical phase shifter
Authors: Akazawa Tomohiro , Monfray Stéphane , Boeuf Frédéric , Toprasertpong Kasidit , Takagi Shinichi , Takenaka Mitsuru
Published: September 2024

Transparent in-line optical power monitoring in Si programmable photonic integrated circuits (PICs) is indispensable for calibrating integrated optical devices such as optical switches and resonators. A Si waveguide (WG) photodetector (PD) based on defect-mediated photodetection is a promising candidate for a transparent in-line optical power monitor, owing to its simplicity and ease of integration with a fully complementary metal–oxide–semiconductor (CMOS)-compatible process. Here, we propose a simple optical power monitoring scheme for a 2 × 2 Mach–Zehnder interferometer (MZI) optical switch based on InGaAsP/Si hybrid MOS optical phase shifters. In the proposed scheme, a low-doped p-type Si WG PD with a response time of microseconds is utilized as a transparent in-line optical power monitor, and the ground terminal of the MOS optical phase shifter is shared with that of the Si WG PD to enable the simple monitoring of the output optical power of the MZI. Based on this scheme, we experimentally demonstrate that the output optical power of a 2 × 2 MZI can be simply monitored by applying a bias voltage to the Si slabs formed at the output WGs of the MZI without excess optical insertion loss.
Toggling near-field directionality via manipulation of matter’s anisotropy
Authors: Ma Wenbo , Chen Xuhuinan , Zhong Yuhan , Bian Chenxu , Wang Chan , Chen Hongsheng , Lin Xiao
Published: September 2024

Near-field directional excitation of dipolar sources is crucial for many practical applications, such as quantum optics, photonic integrated circuits, and on-chip information processing. Based on theoretical analyses and numerical simulations, here we find that the near-field directionality of circularly polarized dipoles can be flexibly toggled by engineering the anisotropy of the surrounding matter, in which the dipolar source locates. To be specific, if the circularly polarized dipole is placed close to the interface between a hyperbolic matter and air, the main propagation direction of excited surface waves would be reversed when the location of the dipolar source is changed from the air region to the hyperbolic-matter region. The underlying mechanism is that the spatial-frequency spectrum of evanescent waves carried by the dipolar source in a homogeneous surrounding matter could be flexibly reshaped by the matter’s anisotropy, especially when the isofrequency contour of the surrounding matter changes from the circular shape to the hyperbolic one.
Supercontinuum saturation of a femtosecond laser filament in pressurized gases
Authors: Geints Yury E. , Bulygin Andrey D. , Kompanets Victor O. , Chekalin Sergey V.
Published: September 2024

Filamentation of high-power femtosecond optical pulses in high-pressure gases has gained increasing academic and practical interest from the viewpoint of studying large-scale spectral and temporal transformations occurring with pulsed laser radiation and obtaining super-broadened spectra and extremely short (attosecond) wave packets. Experimentally and theoretically, for the first time to the best of our knowledge, we show that as a result of a 45 fs Ti:sapphire laser pulse filamentation in an optical cell filled with pressurized up to 50 bar nitrogen or argon, the pulse spectrum can reach maximally about eightfold broadening. This limiting pulse spectral width is reached at a gas pressure of about 20 bar and with further pressure increase exhibits saturation and even a slight decrease relative to the limiting value. As a possible reason for this finding, we suppose the increase of pulse energy depletion in the self-created plasma at high gas pressure.
High sensitivity optical pressure sensor based on graphene/molybdenum disulfide composite film
Authors: Yang Fuling , Zong Sicheng , Du Songlin , Yu Xiaoyi , Lu Ke , Liang Shuai , Cao Le , Li Yan
Published: September 2024

In this paper, a high sensitivity optical pressure sensor based on a graphene/molybdenum disulfide (MoS2) composite film is proposed. The sensor is composed of a polydimethylsiloxane (PDMS) pyramid structure, graphene/MoS2 composite film, and lithium niobate waveguide. The pressure deforms the PDMS pyramid structure, which leads to the change of the refractive index of the graphene/MoS2 composite film, and finally be detectable sensitively by the variation of the interference spectrum. Experiments have been carried out using our sensor prototype, and the sensitivity is up to 575.233 nm/kPa in the pressure range of 0 kPa–0.123 kPa, which is much higher than that of typical optical pressure sensors. This shows the advantages of high sensitivity optical pressure sensors based on the graphene/MoS2 composite film, which is expected to be applied in highly sensitive pressure detection environments.
Dual-band graphene-based polarization-independent Maze-shaped absorber in terahertz biomedical sensing
Authors: Khodadadi Bahareh , Rezaei Pejman , Hadipour Soheil
Published: September 2024

This paper introduces an adjustable metamaterial absorber in terahertz spectrum which has exclusive properties such as resistance to polarization variation. Although this absorber can operate in various applications like chemical and environmental industries, its captivating features in different refractive index (RI) make it a good choice to use in sensing and biomedical applications like cancer early detection, blood glucose, and detecting malaria mosquito bites. The structure originally includes of four different layers that from top to bottom follows: graphene/ SiO2/Si/Au, Respectively, and the finite integration technique has been used in simulation. In terms of absorbing parameters the proposed structure shows an excellent absorption of 98.32% at 4.3 THz and 98.49% at 7.35 THz with an average Q-factor of 8.92 by following simple absorption rules, simulation and electrical field distribution of the suggested structure is illustrated through diagrams to take various parameters such as frequency, sensitivity and physical mechanism into consideration.
Orthogonal CORDIC-based Rotation Phase Interrogation for EFPI Fabry-Perot Sensor
Authors: Li Ruofei , Ma Zhibo , Xi Qi , Tian Zhiyong , Chang zhichuang , xu xulong
Published: September 2024

In response to the growing demand for high-real-time F-P demodulation algorithms, we present a novel Hilbert orthogonal F-P demodulation algorithm, HT-CORDIC, which is based on the Coordinate Rotation Digital Computer (CORDIC) algorithm. HT-CORDIC aims to balance accuracy and real-time performance. The algorithm employs the Hilbert transform to identify orthogonal signals, determines a specific phase difference through the Givens transform, and then extracts the cavity length through vector of the CORDIC algorithm. The algorithm was evaluated through a series of demodulation simulations and experiments conducted on the EFPI sensors. The results demonstrate that the demodulation accuracy is approximately 1 nm at a cavity length of 192.395μm. Furthermore, the algorithm demonstrates an exceptionally high degree of linearity, with an R2 value of 0.9999. The proposed parallel structure algorithm has been demonstrated to reduce the computation time by a factor of 35,138 in comparison to the traditional correlation coefficient method. Furthermore, the resolution was found to be satisfactory, at 2.23nm, with an average of 0.2533nm for the algorithmic noise MSE. It can be concluded that the HT-CORDIC algorithm has the potential to be employed for high-real-time F-P interferometric demodulation.
Perfect self-similar beams
Authors: QIN Yi-qiang , Wang Chenglong , Lu Ronger , Zhao Ruizhi , Li Jialing , Zhu Miao , Sun Xuhui , Gao Bing , Ma Yibing , Zhang Chao , Lu Yanqing
Published: September 2024

We present a new type of beams which are exact solutions to the paraxial Helmholtz equation. Such beams feature strict self-similar transverse profile during the propagation, and the peak intensity remains unchanged. These beams constitute a unique beam mode in free space, which can be regarded as an intermediate mode between non-diffracting beams and traditional self-similar beams. Thus, we name these beams the “perfect self-similar beams”. We show that the transverse profile of these beams scales parabolically during propagation. As such, our work reveals a previously unnoticed beam mode which holds both main characteristics of self-similar beams and non-diffracting beams, and expands conceptually the special beam modes.
Anomalous noise spikes beating from a fine-splitting mode of surface-emitting laser with imperfect true-roundness aspect
Authors: Huang Kun-You , Weng Jui-Hung , Wang Jiaxing , Chang-Hasnain Constance J. , Lin Gong-Ru
Published: September 2024

High-frequency discrete and distinct mode-beating noise (MBN) spectra are an anomalous phenomenon observed in the related intensity noise spectrum from the vertical-cavity surface-emitting laser (VCSEL), which reveals strong correlation with fine-splitting transverse modes caused by non-circular emission aspect of the VCSEL with imperfect true-roundness. Such a phenomenon is demonstrated for the first time, which seriously degrades the transmission performance of high-speed and broad-band encoding data carried by the multi-mode (MM) VCSEL biased under a large DC bias. In this work, the 4-ary quadrature-amplitude modulation (4-QAM) orthogonal frequency-division multiplexing (OFDM) and the non-return-to-zero on–off keying (NRZ-OOK) transmissions with the direct modulation of different 850-nm MM VCSELs, as suffered from the MBN-induced notches of the signal-to-noise-ratio (SNR) spectra, are characterized under their high-level lasing conditions with multi-mode numbers. The significant SNR degradation on the receiving and decoding performances caused by the cross-correlation between MBN and data spectra is also examined by tuning the lensed fiber along the transverse (X/Y)-axis of the VCSEL (perpendicular to the surface normal) when collimating the output beam, which finds the disorderly shifted MBN spectra, as attributed to the collection of light emitted from the overlapped gain region of different transverse modes. In contrast, the MBN reveals invariant spectral features while the lensed fiber is either back-and-forth tuning along the vertical (Z)-axis (parallel with the surface normal) or tilting its angles from the surface normal under the same horizontal position and distance concerning the MM VCSEL. Such MM VCSEL exhibits several MBN spikes to decay the SNRs of NRZ-OOK and QAM OFDM data encoded around 21 and 34 GHz. For other MM VCSELs with reducing numbers of their transverse lasing modes and deforming roundness of their circular emitting aspects, the corresponding MBN spectral peaks can also be respectively observed at 14/17/24 GHz and 4.5/10.5/13 GHz to degrade the SNRs of the encoded data at such frequencies. Even though pre-emphasized encoding technology is employed, such an MBN effect is strongly correlated with the asymmetric circular aspect of the VCSEL with a degraded roundness ratio, which still affects the data modulation performance of the MM VCSEL for data center communication.
Assessment of knowledge of human papillomavirus transmission and prevention among tertiary institution students in the Plateau Central Senatorial District, Nigeria
Authors: Rume Juliana , Morhason-Bello Imran O. , Oladokun Adesina
Published: September 2024

Human papillomavirus infection (HPV) is a significant global public health concern, known to be a leading cause of cancer related death among women in sub-Saharan Africa. This study assessed knowledge of HPV infection, transmission, prevention, and HPV vaccine uptake among tertiary institution students in Plateau State, Nigeria. A cross-sectional study was conducted among students from two tertiary institutions in Plateau State, Nigeria. Using a structured pretested questionnaire, data were collected from participants selected by two-stage sampling technique. Participants’ responses were analysed to assess their knowledge regarding HPV transmission, prevention, and vaccination. A composite score was obtained for the general HPV knowledge. A score of more than 70.0% indicated good knowledge. The distribution of the variables was examined using frequency distribution and descriptive statistics. The chi-square test was performed for bivariate analysis. Logistics regression was performed to examine the odds of having good HPV knowledge among the students. Level of significant was set at 95%. Of the 425 participants, 302 (71.1%) were female and 123 (28.9%) were male, with a mean age of 23 ± 2.8 years. There was low awareness of HPV among participants, with higher awareness among the females 66 (23.1%) than the males 26 (22.2%) (p = .853). Both female 77 (26.1%) and male participants 31 (26.72%) had low awareness of HPV vaccination. Among all participants, only 19 (5%) demonstrated good knowledge of HPV. Participants who were employed significantly had good knowledge of HPV compared to those who were unemployed. There was inadequate general knowledge of HPV and its vaccination among tertiary institution students in Plateau State, Nigeria. The students’ employment status was associated with their knowledge of HPV. Targeted educational programs focusing on diverse educational levels and institution types are recommended to enhance HPV knowledge and promote vaccine uptake.
Current out of pocket care costs among HIV and hypertension co-morbid patients in urban and peri-urban Uganda
Authors: Cameron Drew B. , Morrell Lillian C. , Kagoya Faith , Kiggundu John Baptist , Hutchinson Brian , Twine Robert , Schwartz Jeremy I. , Muddu Martin , Mutungi Gerald , Kayima James , Katahoire Anne R. , Longenecker Chris T. , Nugent Rachel , Loya David Contreras , Semitala Fred C.
Published: September 2024

Background

Despite improvements to the cascade of HIV care in East Africa, access to care for non-communicable disease co-morbidities like hypertension (HTN) remains a persistent problem. The integration of care for these conditions presents an opportunity to achieve efficiencies in delivery as well as decrease overall costs for patients. This study aims to build evidence on the burden of current out-of-pocket costs of care among HIV-HTN co-morbid patients.

Methods

We administered a pre-tested, cross-sectional, out-of-pocket cost survey to 94 co-morbid patients receiving HIV care from 10 clinics in the Wakiso and Kampala districts of Uganda from June to November 2021. The survey assessed socio-demographic characteristics, direct medical costs (e.g., medications, consultations), indirect costs (e.g., transport, food, caregiving), and economic costs (i.e., foregone income) associated with seeking HIV and HTN care, as well as possible predictors of monthly care costs. Patients were sampled both during a government-imposed nation-wide full COVID-19 lockdown (n = 30) and after it was partially lifted (n = 64).

Results

Median HIV care costs constitute between 2.7 and 4.0% of median monthly household income, while HTN care costs are between 7.1 to 7.9%. For just under half of our sample, the median monthly cost of HTN care is more than 10% of household income, and more than a quarter of patients report borrowing money or selling assets to cover costs. We observe uniformly lower reported costs of care for both conditions under full COVID-19 lockdown, suggesting that access to care was limited. The main predictors of monthly HIV and HTN care costs varied by disease and costing perspective.

Conclusions

Patient out of pocket costs of care for HIV and HTN were substantial, but significantly lower during the 2021 full COVID-19 lockdown in Uganda. New strategies such as service integration need to be explored to reduce these costs.
ST8Sia2 polysialyltransferase protects against infection by Trypanosoma cruzi
Authors: Barboza Bruno Rafael , Macedo-da-Silva Janaina , Silva Lays Adrianne Mendonça Trajano , Gomes Vinícius de Morais , Santos Deivid Martins , Marques-Neto Antônio Moreira , Mule Simon Ngao , Angeli Claudia Blanes , Borsoi Juliana , Moraes Carolina Borsoi , Moutinho-Melo Cristiane , Mühlenhoff Martina , Colli Walter , Marie Suely Kazue Nagashi , Pereira Lygia da Veiga , Alves Maria Julia Manso , Palmisano Giuseppe
Published: September 2024

Glycosylation is one of the most structurally and functionally diverse co- and post-translational modifications in a cell. Addition and removal of glycans, especially to proteins and lipids, characterize this process which has important implications in several biological processes. In mammals, the repeated enzymatic addition of a sialic acid unit to underlying sialic acids (Sia) by polysialyltransferases, including ST8Sia2, leads to the formation of a sugar polymer called polysialic acid (polySia). The functional relevance of polySia has been extensively demonstrated in the nervous system. However, the role of polysialylation in infection is still poorly explored. Previous reports have shown that Trypanosoma cruzi (T. cruzi), a flagellated parasite that causes Chagas disease (CD), changes host sialylation of glycoproteins. To understand the role of host polySia during T. cruzi infection, we used a combination of in silico and experimental tools. We observed that T. cruzi reduces both the expression of the ST8Sia2 and the polysialylation of target substrates. We also found that chemical and genetic inhibition of host ST8Sia2 increased the parasite load in mammalian cells. We found that modulating host polysialylation may induce oxidative stress, creating a microenvironment that favors T. cruzi survival and infection. These findings suggest a novel approach to interfere with parasite infections through modulation of host polysialylation.
Perceived travel distance depends on the speed and direction of self-motion
Authors: Bansal Ambika , McManus Meaghan , Jörges Björn , Harris Laurence R.
Published: September 2024

Although estimating travel distance is essential to our ability to move through the world, our distance estimates can be inaccurate. These odometric errors occur because people tend to perceive that they have moved further than they had. Many of the studies investigating the perception of travel distance have primarily used forward translational movements, and postulate that perceived travel distance results from integration over distance and is independent of travel speed. Speed effects would imply integration over time as well as space. To examine travel distance perception with different directions and speeds, we used virtual reality (VR) to elicit visually induced self-motion. Participants (n = 15) were physically stationary while being visually “moved” through a virtual corridor, either judging distances by stopping at a previously seen target (Move-To-Target Task) or adjusting a target to the previous movement made (Adjust-Target Task). We measured participants’ perceived travel distance over a range of speeds (1–5 m/s) and distances in four directions (up, down, forward, backward). We show that the simulated speed and direction of motion differentially affect the gain (perceived travel distance / actual travel distance). For the Adjust-Target task, forwards motion was associated with smaller gains than either backward, up, or down motion. For the Move-To-Target task, backward motion was associated with smaller gains than either forward, up or down motion. For both tasks, motion at the slower speed was associated with higher gains than the faster speeds. These results show that transforming visual motion into travel distance differs depending on the speed and direction of optic flow being perceived. We also found that a common model used to study the perception of travel distance was a better fit for the forward direction compared to the others. This implies that the model should be modified for these different non-forward motion directions.
Design of multivalent-epitope vaccine models directed toward the world’s population against HIV-Gag polyprotein: Reverse vaccinology and immunoinformatics
Authors: Hashempour Ava , Khodadad Nastaran , Bemani Peyman , Ghasemi Younes , Akbarinia Shokufeh , Bordbari Reza , Tabatabaei Amir Hossein , Falahi Shahab
Published: September 2024

Significant progress has been made in HIV-1 research; however, researchers have not yet achieved the objective of eradicating HIV-1 infection. Accordingly, in this study, eucaryotic and procaryotic in silico vaccines were developed for HIV-Gag polyproteins from 100 major HIV subtypes and CRFs using immunoinformatic techniques to simulate immune responses in mice and humans. The epitopes located in the conserved domains of the Gag polyprotein were evaluated for allergenicity, antigenicity, immunogenicity, toxicity, homology, topology, and IFN-γ induction. Adjuvants, linkers, CTLs, HTLs, and BCL epitopes were incorporated into the vaccine models. Strong binding affinities were detected between HLA/MHC alleles, TLR-2, TLR-3, TLR-4, TLR-7, and TLR-9, and vaccine models. Immunological simulation showed that innate and adaptive immune cells elicited active and consistent responses. The human vaccine model was matched with approximately 93.91% of the human population. The strong binding of the vaccine to MHC/HLA and TLR molecules was confirmed through molecular dynamic stimulation. Codon optimization ensured the successful translation of the designed constructs into human cells and E. coli hosts. We believe that the HIV-1 Gag vaccine formulated in our research can reduce the challenges faced in developing an HIV-1 vaccine. Nevertheless, experimental verification is necessary to confirm the effectiveness of these vaccines in these models.
Evaluating the efficacy of multi-incision and tube-dragging therapy combined with laser closure for high horseshoe-shaped anal fistula: Protocol of a prospective, randomized, controlled trial
Authors: Yang Min , Mei Zubing , Wang Qingming , Han Ye , Zheng De
Published: September 2024

Introduction

High horseshoe-shaped anal fistula (HHAF) is a complicated and challenging condition that presents considerable obstacles in treatment. We are presently investigating a novel surgical technique involving a combination of multi-incision and tube-dragging therapy, and laser closure (MITD-LaC) for the management of HHAF. Due to the current scarcity of rigorous evidence evaluating this approach, it is essential to perform a well-designed randomized controlled trial to compare the effectiveness of this new method with incision and thread-drawing therapy.

Methods and analysis

This trial is a prospective, randomized, controlled and interventional study. After preliminary screening of qualified outpatients, a total of 64 adult patients will be enrolled in the trial and randomly allocated to either the MITD-LaC group or the control group (n = 32 per group). These patients will receive either MITD-LaC or incision and thread-drawing therapy. The design aims to allow for a robust comparison between the two treatment modalities. The primary endpoint is the wound healing time, while secondary endpoints include postoperative anal pain at 1, 3, and 5 days (measured with visual analogue scale), fecal incontinence score within 30 days after operation (measured with Cleveland Clinic Florida incontinence score), and the occurrence of postoperative complications within 1 month after surgery, and quality of life up to six months postoperatively (evaluated by The Quality of Life in patients with Anal Fistula Questionnaire Score).

Discussion

This study represents the first randomized controlled trial evaluating the short-term outcomes of MITD-LaC, thereby aiming to contribute high-quality evidence to guide clinical practice. Moreover, this trial incorporates comprehensive outcome measures assessing both subjective and objective dimensions. Because of this multidimensional assessment, MITD-LaC offers a promising potential for broader application in the treatment of HHAF. Consequently, obtaining more definitive and authoritative evidence through scientifically rigorous clinical trials is of utmost importance in further validating this treatment approach.

Ethics and dissemination

We have submitted the clinical study protocol to the Ethics Committee, and it has been approved under ethical approval number 2021-1036-111-01. The results of the trial will be disseminated through peer-reviewed academic journals and presentations at professional conferences.

Registration number

ChiCTR2100053556.
A novel development to encrypt data communication under t-intuitionistic fuzzy environment
Authors: Alolaiyan Hanan , Latif Laila , Shuaib Umer , Razaq Abdul , Xin Qin
Published: September 2024

The field of cryptography has grown significantly with the advent of information and communication technologies due to the increasing complexity of cyber threats and rising security requirements. This evolution has come with the creation of new cryptosystems and improvements to current ones. This study is the first to explore the RSA approach in the framework of t-intuitionistic fuzzy subgroups. This technique makes group-based cryptographic operations safer when there are unclear relationships and hesitations. This supports the complex and uncertain nature of subgroup membership, allowing for much more significant representations of the degrees of belonging, non-belonging, and hesitancy for the group elements along parameter ’t’. The t-intuitionistic fuzzy RSA technique employs a t-intuitionistic fuzzy subgroup to address cryptosystem ambiguity, fuzziness, and imprecision. Consequently, inaccurate cryptographic data is more effectively represented, manipulated, and protected. Furthermore, this technique enhances the current level of fuzzy cryptography. The t-intuitionistic fuzzy RSA algorithms are of theoretical and practical value, as they significantly contribute towards developing fuzzy cryptography, fuzzy algebraic structures, and decision support systems. In this paper, the notions of t-intuitionistic fuzzy numbers and triangular t-intuitionistic fuzzy numbers are introduced. A new RSA cryptosystem based on a t-intuitionistic fuzzy subgroup is proposed in which the plaintext and the ciphertext are obtained in terms of t-intuitionistic fuzzy numbers and triangular t-intuitionistic fuzzy numbers. In addition, the significance of the concept of the t-intuitionistic fuzzy subgroup is highlighted as a suitable alternative tool to secure the data under consideration. In addition, the practical effect of the proposed methods is also investigated in this study. A mathematical mechanism is presented to implement the t-intuitionistic fuzzy RSA algorithm. Finally, a comparative analysis of the developed technique is presented with some existing methods to showcase the applicability and superiority of the recently developed method.
A SONAR report on Nirmatrelvir/ritonavir-associated rebound COVID-19: Using new databases for evaluating new diseases
Authors: Bennett Charles L. , Magagnoli Joseph , Gundabolu Krishna , Georgantopoulos Peter , Lebby Akida , Watson Gretchen , Knopf Kevin , Martin Linda , Carson Kenneth R. , Hrushesky William J. , Nabhan Chadi , Zyszkowski Edward , Smith Edward B. , Gale Robert Peter , Rosen Steven T.
Published: September 2024

Introduction

In May 2022, the Centers for Disease Control and Prevention disseminated an alert advising that “a few” persons with Nirmatrelvir/ritonavir (NM/R)-associated rebound of COVID-19 infection had been identified. Three case reports appearing as pre-print postings described the first cases. Analyses in March 2023 by NM/R’s manufacturer and the Food and Drug Administration (FDA) reported no association between NM/R and COVID-19 rebound in a large phase 3 randomized clinical trial. Our study evaluated if social media databases or electronically disseminated new articles might provide insights related to the putative new toxicity, NM/R-associated COVID-19 rebound.

Methods

Information on NM/R-associated COVID-19 rebound cases was abstracted from preprint postings of non-peer-reviewed manuscripts, social media websites, electronically disseminated print and television media reports, a new FDA adverse event database for drugs that received Emergency Use Approval, and news articles in scientific journals.

Results

Thirty-five persons experienced presumed or documented NM/R-associated COVID-19 rebound, based on information described in preprint services (n = 27), Twitter postings and related news articles (n = 7), and news articles without related Twitter reports (n = 1). These reports included information on dates of initial COVID-19 illness and rebound onset, COVID-19 testing, vaccine status, presentation, and outcome. A new FDA safety database identified 12,500 possible cases of this toxicity, but the quality of these data was poor. Preprint postings preceded peer-reviewed publications describing the same cases by four months. Social media websites including Instagram, Reddit, YouTube, the Center for Disease Control and Prevention’s (CDC) Health Alert Network, CDC Twitter, and Facebook did not provide clinically meaningful information on individual cases.

Conclusion

Preprint services and Twitter facilitated identification of the largest case series of NM/R-associated COVID-19 rebound. The cases were reported in non-peer-reviewed media several weeks prior to the first peer-reviewed electronically disseminated publication of one person with this diagnosis.
Farmers’ perceptions on stock theft in some districts of the Eastern Cape Province, South Africa
Authors: Ndzungu Kanya , Jaja Ishmael Festus
Published: September 2024

Stock theft is a persistent and widespread problem affecting farmers in the Eastern Cape Province of South Africa. This study aimed to explore farmers’ perceptions of stock theft in the region. A mixed methods approach was used to collect data. 192 pre-tested questionnaires were collected from a sample of farmers in three districts in the province. The descriptive and chi-square test was used to test the associations between demographic profile statistically, knowledge of stock theft, reported stock theft cases, the economic impact of stock theft, and stock theft control. According to the findings, stock theft is significantly more likely to occur during the winter season (P < 0.05). About 94.8% of farmers are in the communal farming sector in the three districts visited. Furthermore, 81.2% of the respondents believe that the government needs to do more to combat the spread of stock theft. This study also revealed that most respondents (88.6%) agree that branding and tattooing should be made available to all registered farmers, while 53.1% believe that forensic deoxyribonucleic acid should not be used to control stock theft at crime scenes. This study highlights farmers’ perceptions and knowledge of stock theft to enable policymakers to develop targeted interventions and strategies. Policing strategy must be adaptive and technology-driven to fast-track detection, prevention, and reduction of stuck theft crime.
Modelling the effects of 4-factor prothrombin complex concentrate for the management of factor Xa-associated bleeding
Authors: Muir Ineke , Herzog Eva , Brechmann Markus , Ghobrial Oliver , Rezvani Sharif Alireza , Hoffman Maureane
Published: September 2024

The management of factor Xa (FXa) inhibitor-associated bleeding remains a clinical challenge. Massive bleeding is often associated with complex coagulopathy and, thus, the sole reversal of FXa inhibitors might not be sufficient to restore hemostasis, requiring instead a multimodal approach. Four-factor prothrombin complex concentrate (4F-PCC) is widely recognized as a viable treatment option for FXa inhibitor-associated bleeding. Here, we applied computational models to explore the effect 4F-PCC has on the coagulation cascade and restoration of thrombin generation in a system that simulates a patient that has received a FXa inhibitor. The coagulation model is largely based on a previously developed model with modifications incorporated from various other published sources. The model was calibrated and validated using data from a phase 3 clinical trial of vitamin K antagonist reversal with 4F-PCC. Using the parameters and initial conditions determined during the calibration and validation process, the prothrombin time (PT) test simulations predicted a PT of 11.4 seconds. The model successfully simulated the effects of rivaroxaban and apixaban on total thrombin concentration and showed that 4F-PCC increased thrombin generation in the presence of rivaroxaban or apixaban.