Scaled-laboratory demonstrations of deep-turbulence conditions.

This paper uses five spatially distributed reflective liquid-crystal phase modulators (LcPMs) to accurately simulate deep-turbulence conditions in a scaled-laboratory environment. In practice, we match the Fresnel numbers for long-range, horizontal-path scenarios using optical trombones and relays placed between the reflective LcPMs. Similar to computational wave-optic simulations, we also command repeatable high-resolution phase screens to the reflective LcPMs with the proper path-integrated spatial and temporal Kolmogorov statistics.

"Hidden phase" in two-wavelength adaptive optics.

Two-wavelength adaptive optics (AO), where sensing and correcting (from a beacon) are performed at one wavelength λ B and compensation and observation (after transmission through the atmosphere) are performed at another λ T , has historically been analyzed and practiced assuming negligible irradiance fluctuations (i.e., weak scintillation). Under these conditions, the phase corrections measured at λ B are robust over a relatively large range of wavelengths, resulting in a negligible decrease in AO performance. In weak-to-moderate scintillation conditions, which result from distributed-volume atmospheric aberrations, the pupil-phase function becomes discontinuous, producing what Fried called the "hidden phase" because it is not sensed by traditional least-squares phase reconstructors or unwrappers. Neglecting the hidden phase has a significant negative impact on AO performance even with perfect least-squares phase compensation. To the authors' knowledge, the hidden phase has not been studied in the context of two-wavelength AO. In particular, how does the hidden phase sensed at λ B relate to the compensation (or observation) wavelength λ T ? If the hidden phase is highly correlated across λ B and λ T , like the least-squares phase, it is worth sensing and correcting; otherwise, it is not. Through a series of wave optics simulations, we find an approximate expression for the hidden-phase correlation coefficient as a function of λ B , λ T , and the scintillation strength. In contrast to the least-squares phase, we determine that the hidden phase (when present) is correlated over a small band of wavelengths centered on λ T . Over the range λ B ,λ T ∈[1,3]µm and in weak-to-moderate scintillation conditions (spherical-wave log-amplitude variance σ χ2∈[0.1,0.5]), we find the average hidden-phase correlation linewidth to be approximately 0.35 µm. Consequently, for |λ B -λ T | greater than this linewidth, including the hidden phase does not significantly improve AO performance over least-squares phase compensation.

Speckle-free coherent imaging through deep turbulence.

We develop and validate a model-based iterative reconstruction framework for digitally correcting coherent images corrupted by deep turbulence. In general, this framework is applicable to coherent-imaging approaches that gain access to the complex-optical field; however, we demonstrate our approach with multi-shot digital holography data. To test our image correction framework, we generate calibrated deep-turbulence conditions from our laboratory testbed. Using the resulting data, we demonstrate groundbreaking performance in terms of speckle-free image correction in deep-turbulence conditions.

Tracking bandwidth limitations for strong optical-turbulence conditions.

We derive a modified fundamental tracking frequency that is applicable for beam-control systems that do not employ adaptive-optics compensation. Specifically, we show that there are diminishing returns on tracking faster than the modified fundamental tracking frequency. Furthermore, when D/r0 > 4, where D is the aperture diameter and r0 is the Fried parameter, we show that increasing the track bandwidth alone will not improve system performance. These conclusions result from beam spreading being the dominant driver of decreased system performance, as opposed to beam jitter.

Genomic landscape of NDM-1 producing multidrug-resistant Providencia stuartii causing burn wound infections in Bangladesh.

The increasing antimicrobial resistance in Providencia stuartii (P. stuartii) worldwide, particularly concerning for immunocompromised and burn patients, has raised concern in Bangladesh, where the significance of this infectious opportunistic pathogen had been previously overlooked, prompting a need for investigation. The two strains of P. stuartii (P. stuartii SHNIBPS63 and P. stuartii SHNIBPS71) isolated from wound swab of two critically injured burn patients were found to be multidrug-resistant and P. stuartii SHNIBPS63 showed resistance to all the 22 antibiotics tested as well as revealed the co-existence of blaVEB-6 (Class A), blaNDM-1 (Class B), blaOXA-10 (Class D) beta lactamase genes. Complete resistance to carbapenems through the production of NDM-1, is indicative of an alarming situation as carbapenems are considered to be the last line antibiotic to combat this pathogen. Both isolates displayed strong biofilm-forming abilities and exhibited resistance to copper, zinc, and iron, in addition to carrying multiple genes associated with metal resistance and the formation of biofilms. The study also encompassed a pangenome analysis utilizing a dataset of eighty-six publicly available P. stuartii genomes (n = 86), revealing evidence of an open or expanding pangenome for P. stuartii. Also, an extensive genome-wide analysis of all the P. stuartii genomes revealed a concerning global prevalence of diverse antimicrobial resistance genes, with a particular alarm raised over the abundance of carbapenem resistance gene blaNDM-1. Additionally, this study highlighted the notable genetic diversity within P. stuartii, significant informations about phylogenomic relationships and ancestry, as well as potential for cross-species transmission, raising important implications for public health and microbial adaptation across different environments.

Unveiling a high-risk epidemic clone (ST 357) of 'Difficult to Treat Extensively Drug-Resistant' (DT-XDR) Pseudomonas aeruginosa from a burn patient in Bangladesh: A resilient beast revealing coexistence of four classes of beta lactamases.

OBJECTIVES: Pseudomonas aeruginosa (P. aeruginosa) stands out as a key culprit in the colonization of burn wounds, instigating grave infections of heightened severity. In this study, we have performed comparative whole genome analysis of a difficult to treat extensively drug resistant P. aeruginosa isolated from a burn patient in order to elucidate genomic diversity, molecular patterns, mechanisms and genes responsible for conferring antimicrobial resistance and virulence. METHOD: P. aeruginosa SHNIBPS206 was isolated from an infected burn wound of a critically injured burn patient. Whole genome sequencing was carried out and annotated with Prokka. Sequence type, serotype, antimicrobial resistance genes and mechanisms, virulence genes, metal resistance genes and CRISPR/Cas systems were investigated. Later, pangenome analysis was carried out to find out genomic diversity. RESULT: P. aeruginosa SHNIBPS206 (MLST 357, Serotype O11) was resistant to 14 antibiotics including carbapenems and harboured all four classes of beta lactamase producing genes: Class A (blaPME-1, blaVEB-9), Class B (blaNDM-1), Class C (blaPDC-11) and Class D (blaOXA-846). Mutational analysis of Porin D gave valuable insights. Several efflux pump, virulence and metal resistance genes were also detected. Pangenome analysis revealed high genomic diversity among different strains of P. aeruginosa. CONCLUSION: To our knowledge, this is the first report of an extensively drug resistant ST 357 P. aeruginosa from Bangladesh, which is an epidemic high-risk P. aeruginosa clone. Further research and in-depth comprehensive studies are required to investigate the prevalence of such high-risk clone of P. aeruginosa in Bangladesh.

Active-illumination extension to the Priest and Meier pBRDF.

This paper develops a 3D vector solution for the scattering of partially coherent laser-beam illumination from statistically rough surfaces. Such a solution enables a rigorous comparison to the well-known Priest and Meier polarimetric bidirectional reflectance distribution function (pBRDF) [Opt. Eng.41(5), 988 (2002)10.1117/1.1467360]. Overall, the comparison shows excellent agreement for the normalized spectral density and the degree of polarization. Based on this agreement, the 3D vector solution also enables an extension to the Priest and Meier pBRDF that accounts for the effects of active illumination. In particular, the 3D vector solution enables the development of a closed-form expression for the spectral degree of coherence. This expression provides a gauge for the average speckle size based on the spatial-coherence properties of the laser source. Such an extension is of broad interest to long-range applications that deal with speckle phenomena.

System-level noise performance of coherent imaging systems.

We provide an in-depth analysis of noise considerations in coherent imaging, accounting for speckle and scintillation in addition to "conventional" image noise. Specifically, we formulate closed-form expressions for total effective noise in the presence of speckle only, scintillation only, and speckle combined with scintillation. We find analytically that photon shot noise is uncorrelated with both speckle and weak-to-moderate scintillation, despite their shared dependence on the mean signal. Furthermore, unmitigated speckle and scintillation noise tends to dominate coherent-imaging performance due to a squared mean-signal dependence. Strong coupling occurs between speckle and scintillation when both are present, and we characterize this behavior by fitting a scale factor capable of generating variances in closed form. We verify each of these claims through a series of wave-optics simulations, and we see strong agreement in general between numerical results and theoretical predictions. Our findings allow us to confidently gauge signal-to-noise ratio (SNR) expectations when active illumination produces coherent noise.

Clinical outcomes of posterior tibial tendon sheath ultrasound-guided corticosteroid injections.

Objectives: The purpose of this study was to assess the safety of ultrasound-guided corticosteroid injections into the posterior tibial tendon sheath for posterior tibialis tendinopathy. Secondary outcomes include duration of pain relief, amount of pain relief, need for repeat injections and progression to surgery. Methods: We retrospectively reviewed all patients in our electronic medical record who underwent a posterior tibial tendon sheath (PTTS) steroid injection between 2015 and 2020 for the diagnosis of posterior tibial tendon dysfunction and/or posterior tibialis tendon insufficiency, and/or ankle pain. Demographic information was obtained from the patient record in addition to MRI data, clinical response to injection based on follow-up visits, number of total injections and progression to surgery. Thirty-eight posterior tibial tendon sheath ultrasound-guided injections were administered in 33 patients who met inclusion criteria during the 5-year study period. Results: Thirty-three patients were included in the study with a total of 38 injections performed. Eighteen of 38 (47%) injections yielded good or better pain relief. Seven of 33 patients (21%) progressed to surgery. There were no reported complications with the 38 performed injections. Conclusion: Ultrasound-guided corticosteroid injection into the posterior tibial tendon sheath is a safe nonoperative treatment modality for progressive collapsing foot deformity. The efficacy of the injection appears highly variable with 47% of injections yielding 'good' or better clinical results. When evaluating body mass index (BMI), obese patients (BMI ≥30.0) were found to have a more sustained response to injection (P = 0.029) and more pain relief (P = 0.049) than non-obese patients.

Measuring laser-speckle statistics in scaled-laboratory experiments.

Generating fully developed speckle in a repeatable way is of interest to ongoing scaled-laboratory experiments. Such experiments often look to validate theoretical and numerical predictions for numerous laser-based applications. Unfortunately, experimental constraints such as camera-pixel sampling, residual-sensor noise, and cover-glass etaloning limit one's ability to match the statistics of fully formed speckle in a straightforward way. In this paper, we develop expressions for the speckle probability density function (PDF) and speckle contrast, which account for the effects of camera-pixel sampling (relative to the size of the speckles), as well as Gaussian-distributed additive noise. We validate these expressions using wave-optics simulations, which also account for the separate effects of cover-glass etaloning. Next, we set up an experiment that limits the effects of the cover-glass etaloning (as much as possible). The results show excellent agreement with the expressions we develop for the speckle PDF and speckle contrast. This agreement will enable future scaled-laboratory experiments to match the statistics of fully developed speckle in a straightforward way.

Applications of Lasers for Sensing and Free Space Communications: introduction to the feature issue.

This feature issue highlights the latest developments in laser-based sensing and free space communications. In total, 15 papers were published in Applied Optics, including an invited review paper that celebrates the legacy of David L. Fried.

Genome-wide study of globally distributed respiratory syncytial virus (RSV) strains implicates diversification utilizing phylodynamics and mutational analysis.

Respiratory syncytial virus (RSV) is a common respiratory pathogen that causes mild cold-like symptoms and severe lower respiratory tract infections, causing hospitalizations in children, the elderly and immunocompromised individuals. Due to genetic variability, this virus causes life-threatening pneumonia and bronchiolitis in young infants. Thus, we examined 3600 whole genome sequences submitted to GISAID by 31 December 2022 to examine the genetic variability of RSV. While RSVA and RSVB coexist throughout RSV seasons, RSVA is more prevalent, fatal, and epidemic-prone in several countries, including the United States, the United Kingdom, Australia, and China. Additionally, the virus's attachment glycoprotein and fusion protein were highly mutated, with RSVA having higher Shannon entropy than RSVB. The genetic makeup of these viruses contributes significantly to their prevalence and epidemic potential. Several strain-specific SNPs co-occurred with specific haplotypes of RSVA and RSVB, followed by different haplotypes of the viruses. RSVA and RSVB have the highest linkage probability at loci T12844A/T3483C and G13959T/C2198T, respectively. The results indicate that specific haplotypes and SNPs may significantly affect their spread. Overall, this analysis presents a promising strategy for tracking the evolving epidemic situation and genetic variants of RSV, which could aid in developing effective control, prophylactic, and treatment strategies.

Insights into Omicron's Low Fusogenicity through In Silico Molecular Studies on Spike-Furin Interactions.

The Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant and its subvariants have a unique set of mutations. Two of those mutations (N679 K and P681 H) reside close to the S1 /S2 furin cleavage site (FCS; 685-686). When these mutations reside together, they exert less-efficient membrane fusion than wild type and most other variants of concern such as the Delta variant. Here, we in silico targeted these mutations to find out which of the amino acids and interactions change plays the key role in fusion. To comprehend the epistatic effect of N679 K and P681 H mutations on the spike protein, we in silico constructed three types of spike protein sequences by changing the respective amino acids on 679 and 681 positions (P681 H, N679 K, K679 N-H681 P variants). We then analyzed the binding affinity of furin and spike (Furin-Wild, Furin-Omicron, Furin-P681 H, Furin-N679 K, and Furin-K679 N/H681 P) complexes. Omicron and P681 H variants showed a similar higher binding energy trend compared to the wild type and N679 K. The variation in hydrogen, hydrophobic, and salt bridge bonds between spike protein and furin provided an explanation for the observed low fusogenicity of Omicron. The fate of the epistasis in furin binding and possible cleavage depends on the efficient interaction between FCS in spike and furin catalytic triad, and in addition, the loss of the hydrogen bond between Arg 681 (spike) and Asn 295 (furin) along with inhibitor-like ineffective higher affinity plays an important role in the enzymatic activity.

Autism trends in a medium size coastal town of England.

Autism spectrum disorder (ASD) is a complex set of neurodevelopmental conditions which affects just under 1% of the global population. This study aims to investigate the trends in ASD diagnoses in a typical English deprived coastal community over the last two decades. ASD information for patients registered at Fleetwood GP practices were provided for the period between July 1952 to March 2022. The incidence and prevalence were calculated and Poisson regression modelling was employed to estimate the effects of age and sex on the number of ASD diagnoses over time. The study shows that there has been an upward trend in the number of ASD diagnoses over the past two decades. Model's results showed that sex differences in ASD diagnoses are less pronounced when accounting for time trends. The study findings show that Fleetwood has experienced a similar rise in ASD cases as the rest of the UK, most likely due to increased awareness that may explain the time effects over gender differences. However, due to the small sample size of the study, confirmation of the gender results and identification of the factors determining the temporal trends are needed in order to determine the gender effects in ASD diagnosis.

Active-tracking scaling laws using the noise-equivalent angle due to speckle.

It is well known to system engineers that speckle imposes a limitation on active-tracking performance, but scaling laws that quantify this limitation do not currently exist in the peer-reviewed literature. Additionally, existing models lack validation through either simulation or experimentation. With these points in mind, this paper formulates closed-form expressions that accurately predict the noise-equivalent angle due to speckle. The analysis separately treats both well-resolved and unresolved cases for circular and square apertures. When compared with the numerical results from wave-optics simulations, the analytical results show excellent agreement to a track-error limitation of (1/3)λ/D, where λ/D is the aperture diffraction angle. As a result, this paper creates validated scaling laws for system engineers that need to account for active-tracking performance.

Health Justice Standards in Graduate Medical Education: Moving from Performative to Concrete Change.

BACKGROUND: Inadequate support for underrepresented-in-medicine physicians, lack of physician knowledge about structural drivers of health, and biased patient care and research widen US health disparities. Despite stating the importance of health equity and diversity, national physician education organizations have not yet prioritized these goals. AIM: To develop a comprehensive set of Health Justice Standards within our residency program to address structural drivers of inequity. SETTING: The J. Willis Hurst Internal Medicine Residency Program of Emory University is an academic internal medicine residency program located in Atlanta, Georgia. PARTICIPANTS: This initiative was led by the resident-founded Churchwell Diversity and Inclusion Collective, modified by Emory IM leadership, and presented to Emory IM residents. PROGRAM DESCRIPTION: We used an iterative process to develop and implement these Standards and shared our progress with our coresidents to evaluate impact. PROGRAM EVALUATION: In the year since their development, we have made demonstrable progress in each domain. Presentation of our work significantly correlated with increased resident interest in advocacy (p<0.001). DISCUSSION: A visionary, actionable health justice framework can be used to generate changes in residency programs' policies and should be developed on a national level.

Pulse-quality metric for nonstationary partially coherent fields.

This paper generalizes a pulse-quality metric referred to as P2, i.e., the time analogue of Siegman's beam quality factor M2, to include pulsed (nonstationary) random fields of any state of coherence. The analysis begins with the derivation of a general P2 relation, which we then specialize to the important cases of coherent and Schell-model pulsed beams. As examples, we derive the P2 for two stochastic sources: (1) a cosine Gaussian-correlated Schell-model pulsed beam and (2) a nonuniformly correlated pulsed beam. For both of these sources, we generate (in simulation) random instances of each and compare the simulated (Monte Carlo) P2, i.e., computed directly from its definition, to the theoretical quantity. The agreement is excellent, thereby validating our P2 analysis.

Deep-turbulence phase compensation using tiled arrays.

Tiled arrays use modulo-2π phase compensation and coherent beam combination to correct for the effects of deep turbulence. As such, this paper uses wave-optics simulations to compare the closed-loop performance of tiled arrays to a branch-point-tolerant phase reconstructor known as LSPV+7 [Appl. Opt.53, 3821 (2014)10.1364/AO.53.003821]. The wave-optics simulations make use of a point-source beacon and are setup with weak-to-strong scintillation conditions. This setup enables a trade-space exploration in support of a power-in-the-bucket comparison with LSPV+7. In turn, the results show that tiled arrays outperform LSPV+7 when transitioning from weak-to-strong scintillation conditions. These results are both encouraging and informative for those looking to tackle the branch-point problem in adaptive optics.

Pulsed laser source digital holography efficiency measurements.

In this paper, a 1064 nm pulsed laser source and a short-wave IR (SWIR) camera are used to measure the total system efficiency associated with a digital holography system in the off-axis image plane recording geometry. At a zero path-length difference between the signal and reference pulses, the measured total system efficiency (15.9%) is consistent with that previously obtained with a 532 nm continuous-wave laser source and a visible camera [Appl. Opt.58, G19 (2019)APOPAI0003-693510.1364/AO.58.000G19]. In addition, as a function of the temporal delay between the signal and reference pulses, the total system efficiency is accurately characterized by a component efficiency, which is formulated from the ambiguity function. Even with multimode behavior from the pulsed laser source and substantial dark current noise from the SWIR camera, the system performance is accurately characterized by the resulting ambiguity efficiency.

Estimation of atmospheric optical turbulence strength in realistic airborne environments.

In this paper, atmospheric optical turbulence strength is estimated for realistic airborne environments using a modified phase-variance approach, as well as a modified slope-discrepancy approach. Realistic airborne environments are generated using wave-optics simulations of a plane wave propagating through increasing strengths of homogeneous atmospheric optical turbulence, both with and without aero-optical contamination (from in-flight wavefront sensor data) and additive-measurement noise. In comparison to the modified phase-variance approach, the results show that the modified slope-discrepancy approach more accurately estimates atmospheric optical turbulence strength over a wide range of conditions. Such results are encouraging for realistic airborne environments because they can be scaled to different freestream conditions as long as the boundary layer is considered canonical.