bluuebunny/crossref_metadata_2025 huggingface dataset:
The self-reflexivity in transnational literature: Re-writing the migration in female migrant writers
Authors: Di Martino Maria Luisa
Published: February 2023

The main aim of this paper is to discuss the socio-political meaning of the transnational literary production made by female migrant writers. Thus, it analyses their role in the framework of the ‘hybrid’ literary production of the 21st century in Europe, such as Spain and Italy. Moving away from the idea of national literatures, this paper investigates literature as a geographical and emotional inquiry point and friction between languages, ideas, practices, literary institutions, female authors, and female voices in today’s markets. Hybrid literature written by first and second-generation migrants and displaced people is part of a huger concept of transnational literature, which breaks down with the idea of national identity and transiting towards a new conceptualization of hybridity in the literary production, also based on the translation of writings to other languages. Based on the concept of ‘the location of culture’ and the conceptualization of the Bhabha’s ‘third space’, I will analyse the relation between the positioning of female migrant writers of 21st century and the role of hybridity and the reconceptualization of the ‘third space’ in their literary production. The preliminary findings show, firstly, the idea of reconceptualising it appears in light of the complexity of migrant people's realities and sex-gender differences. By adopting an intersectional lens, focused on the dialectic between gender and race/ethnicity and class, this paper analyses the tensions embedded in the re-positioning of four female migrant writers and their transnational experience (self)reflected in their writings. The present research contributes to the scientific knowledge in the field of cross-cultural literary studies, crossed with the migration study, through questioning the changing gender role and relations in transnational migrant literature. In addition, the findings show that today's reflection on ‘third space’ theory in the diasporic literature seems like an idea to be refined when migrant women are involved.
Discourse: Education, Theory of Politics, and Politics of Theory
Authors: Szkudlarek Tomasz
Published: February 2023

In this paper, I revisit and reflect on my own and my research partners’ attempts at investigating the relationship between education and politics through the lens of discourse theory and discourse analysis methodology. This auto-analytical reflection corresponds to the shift in discourse studies from a technically understood discourse analysis to a more generally conceived discourse-analytical approach (Howarth & Torfing, 2005). Revisiting my own analyses made me understand better not only the specificity of the ways of conducting discourse studies in which I have been involved but also some lessobvious ontological assumptions and methodological problems of discourse studies. One such issue is that as long as discourse analysis is powerful in how it shows power relations, and thus politics within non-political phenomena like education, its application to political theory may reveal how its desire for construing social totalities grounds it in the pedagogical.
Pandemic Burnout, Depression, and Anxiety Among Adolescents: A Network Analysis
Authors: Moroń Marcin , Atłas Karina
Published: February 2023

The COVID-19 pandemic could be regarded as a chronic psychological burden that may lead to prolonged, unmanageable stress, e.g. burnout. Previous studies on COVID-19 have indicated that pandemic burnout was frequent in the general population and could beregarded as a risk factor for psychopathological symptomatology (e.g. depression, anxiety).This study used a network approach to investigate the associations between pandemic burnout symptoms and symptoms of depression and anxiety among Polish adolescents. A total of 389 adolescents participated in a survey in two stages: in June 2021 (shortly after students’ return to schools after the COVID-19 lockdowns were lifted; n = 181) and in September 2021 (shortly after the beginning of the new school year; n = 208). Data were collected by means of a survey aimed at measurement of anxiety, depression, and symptoms of COVID-19 burnout. The network analysis indicated that (1) pandemic burnout is rather a separate syndrome of symptoms compared to depression and anxiety; (2) emotional and mental exhaustion symptoms such as feelings of hopelessness andworthlessness were central to pandemic burnout; (3) the stability of the pandemic burnout symptoms was relatively low, indicating that this syndrome could be dynamic or internally heterogenic.
The Well-Being of the Academic Community During the COVID-19 Pandemic
Authors: Przyborowska Beata , Błajet Piotr , Fopka-Kowalczyk Małgorzata
Published: February 2023

Since 2020, the entire world has been struggling with the SARS-CoV-2 pandemic. The constant increase in the number of sick and dying people and the need for quarantine and social distancing have significantly affected the functioning of people, regardless of their background, age and activities. This article aims to examine the level of well-being among the academic community of Nicolaus Copernicus University in Poland based on the concept of Ken Wilber. To this end, a self-administered questionnaire was developed to assess the overall well-being, as well as the respondents’ well-being related to emotions, relationships, health, and the sense of security and satisfaction experienced during the pandemic. A total of 1,164 university employees and 1,601 doctoral and other students participated in the study. Teachers represented the highest levels of overall well-being, scoring higher than doctoral students and undergraduates. The older the respondents, the higher the perceived levels of overall well-being. These findings indicate that doctoral and other students are struggling with reduced levels of well-being and a reduced sense of the quality of life, displaying signs of emotional difficulties, anxiety and fear.
Climate Change and Uncertainty: An Asset Pricing Perspective
Authors: Barnett Michael
Published: February 2023

Climate change and uncertainty about its potential consequences has become a central concern for economists, investors, and policymakers alike. I use a stochastic, dynamic general equilibrium model where final output is produced using a mix of cheap, dirty inputs and expensive, clean inputs and preferences incorporate aversion to climate model misspecification to analyze the implications of climate change and climate model uncertainty on economic and financial market outcomes. I find that climate change leads to increased clean input production and reduced emissions and that there is a negative price of climate risk that is significantly amplified and increasing in magnitude as climate change increases due to aversion to climate model uncertainty. Existing empirical estimates are consistent with the model implications, highlighting the potentially significant influence of climate model uncertainty on macroeconomic and asset pricing outcomes.

This paper was accepted by Elke Weber, Special Section of Management Science on Business and Climate Change.

Funding: This work was supported by the Energy Policy Institute at Chicago [Dissertation Support Fellowship], the Fama-Miller Center [Liew Fama-Miller Fellowship], the National Science Foundation [Graduate Research Fellowship Award D], and the University of Chicago [Harper (Provost) Dissertation Fellowship].

Supplemental Material: The data files and online appendices are available at https://doi.org/10.1287/mnsc.2022.4635 .
Nursing as a profession of public trust - young people’s opinion
Authors: Kocka Katarzyna , Bartoszek Agnieszka , Owczarska Monika , Ślusarska Barbara
Published: February 2023

Introduction. Introduction. Nursing as a profession of public trust is being continuously evaluated by the recipients of nursing services due to the nature of their activities, functions, the responsibility and the applicable moral and ethical standards. The quality and effects of nursing activities have an impact on the public opinion about the entire group of nursing professionals. The perception of this profession among young people is also crucial with regard to their educational choices.

Aim of the Study. The objective of the study has been to identify the opinions of young people on nursing as a profession of public trust.
Material and Methodology. The study was carried out among 116 students of secondary schools and non-medical higher education institutions in Lublin. The diagnostic survey research method was applied with the use of the questionnaire prepared by the author. The statistical analysis was performed based on the Pareto method, which allows arranging the collected data according to the selected criteria.
Results. All the surveyed were of the opinion that the nursing profession holds a great social significance and is needed due to the nature of the performed professional tasks. Most of the respondents claimed that nursing enjoys public trust and therefore should belong to the group of professions of public trust. The survey results and the analysis carried out using the Pareto method have demonstrated that the major characteristics conditioning public trust are a caring attitude, responsibility, professionalism, attentiveness, empathy, patience and communicativeness.
Conclusions. According to the surveyed young people, nursing enjoys trust and belongs to professions of public trust. The factors determining the social position of nurses are: education, remuneration, responsibility for the life and health of other people and appreciation among patients.
A comparative analysis of job and life satisfaction of nurses working in the traditional system and in the Primary Nursing
Authors: Pilch Dorota , Sienkiewicz Mirela , Grochans Elżbieta , Stanisławska Marzanna , Schneider-Matyka Daria
Published: February 2023

Introduction. Professional work is not only a source of income, but also satisfaction. In Polish hospitals, the traditional care system is dominant, while the primary nursing (PN) model focused on professional activity, creativity in the field of health education, and making independent decisions in accordance with professional competence is definitely less common. Were the primary nursing system to be introduced, it would result in the following benefits: responsibility for the results of nursing care and the possibility of providing continuous care adjusted to patients’ individual needs.
Aim. The aim of this study was to compare the satisfaction of nurses who work in two different systems, primary nursing and the traditional one.
Material and methods. The study group consisted of 200 nurses employed in the traditional system and the primary nursing system. Research instruments included: the Satisfaction with Life Scale (SWLS), the Satisfaction with Work Scale (SWWS), and the authors’ questions concerning self-assessment of various aspects of work. Statistical analysis was conducted using the chisquare test with the Yates correction, and Fisher’s exact test. The level of significance was set at p < 0.05.
Results. Nurses working in the primary nursing system were significantly more satisfied with their job and more satisfied with their lives (p < 0.05). Moreover, they rated occupational status of nursing as higher (p = 0.002) and felt more independent in making patient care related decisions (p = 0.004). Difficulties combining work with private life were found in both groups and no differences between the groups were observed (p > 0.05).
Conclusion. Nurses working in the primary nursing system were more satisfied with their jobs, assessed higher their possibility of work organization.
The use of dietary supplements by the elderly
Authors: Oskędra Iwona , Broszkiewicz Ewa , Zych Beata Ewa
Published: February 2023

Introduction. Life expectancy has expanded – both due to lifestyle changes and medical achievements. Constant health care is required in every aspect in order to maintain its high quality.
Aim. Assessing of elderly persons’ interest in the use of food supplements.
Material and methods. The study covered a group of 100 men and women, 60-80 years of age. The method of diagnostic survey was used; the tool was a 28-point questionnaire prepared by the authors.
Results. Ninety one per cent of the respondents confirmed taking dietary supplements. A substantial group (58%) of the respondents was convinced about their beneficial influence on human health, and 21% did not think it was necessary to use the sesupplements. More than 50% of the respondents used the preparations because they cared for their health. Most of the respondents noticed positive effects of the supplements, such as: an increase of vitality and resistance to diseases, better functioning of the organs of movement. Most respondents purchased the supplements in pharmacies. The use of supplements is perfectly safe in the opinion of 45% of the study group while 28% think it may carry some risks.
Conclusion. The most frequent motivations of diet supplementation was boosting resistance and vitality, supplement irondeficiency, stress management. Diet supplements were used by more women (94.8%) than men (85.7%) and more healthy people(96.9%) than the sick (88.2%) but the difference was not statistically significant.
Assessment of Satisfaction with the Quality of Conventional Treatment in Patients with Diagnosed Civilisation Diseases in the Contex of Professional Nurse Competences
Authors: Ogórek-Tęcza Beata , Zachara Natalia
Published: February 2023

Introduction. Satisfaction with the quality of conventional treatment, including nursing care, in the opinion of patients directly translates into levels of satisfaction, whose quantifiable indicators provide information on quality within the healthcare system. Medical team is required to perform their professional duties with best possible results, which becomes particularly meaningful with respect to patients who suffer from cardiovascular diseases, as they have become an increasingly pressing health issue among the senior population.
Aim. Assessment of competences and evaluation of quality of conventional care among the patients treated for cardiovascular diseases.
Material and methods. Research covered a group of 100 patients hospitalized due to ischemic heart disease and arterial hypertension. Author`s questionnaire was used as research tool with the support of anonymous Questionnaire of Patient Satisfaction (QPS).
Results. The patients taking part in the evaluation and assessing the level of medical care as high accounted for 74%. A significant group (77%) expressed satisfaction with treatment or care procedures they underwent. Similarly, a large group of participants (76%) underlined the fact of receiving the information related to their functioning with the disease. Just as highly patients evaluated the level of cooperation (66%) with the medical team and their promptness in bringing help (60%). A statistically significant correlation between the age of the patients and the level of satisfaction with medical care was noted.
Conclusion. In the opinion of evaluated patients, the general assessment of the quality of care was highly positive. Men and persons from the age group of 66-85 gave a higher assessment of quality of performed medical services. General nursing competences in the educational scope were assessed as being average. Patients with higher education and persons from the age group of 26-45 years of age were harsher critics, more demanding with respect to nurses’ competences.
Factors favoring pregnancy continuation among women hospitalized due to miscarriage threat
Authors: Płoch Kazimiera , Dziedzic Małgorzata , Matuszyk Dorota , Frączek Ewelina
Published: February 2023

Introduction. Miscarriage is a serious medical, social and family problem. It is defined as a premature pregnancy termination before 22nd week and it relates to about 10-15% of recognized pregnancies. Its symptoms usually include painless bleeding from uterus and medium force contraction. With preservative treatment the symptoms disappear and the pregnancy continues to the correct termination. Possible termination methods are limited by potential threats to pregnancy. Chances for success are very high, as long as professional medical assistance is provided.
Aim. Determination of the relationship between socio-demographic factors and the factors accompanying treatment for pregnancy subsistence among women hospitalized due to miscarriage threat.
Material and Methodology. Medical documentation of 145 pregnant women hospitalized due to miscarriage threat in Radom Specialist Hospital between January and March 2014. Statistical analysis was performed with Statistica 10 PL software. Confidence level was assumed at p≤0.05.
Results. T Hospitalization and medical treatment effectiveness for pregnancy subsistence was at 87.6 %. It was statistically proven that the highest impact was exercised by medications applied (p=0.000), bed regime (p=0.040) and a week of pregnancy continuation. Its continuation between 8-16 weeks proved to be the most favorable from among examined pregnant women with threatened pregnancies, for its subsistence (p=0.014).
Conclusion. Pharmacotherapy and rest therapy used during hospitalization had favorable influence upon pregnancy subsistence. There was a positive correlation between pregnancy subsistence, folic acid supplementation, correct BMI and the week when miscarriage occurred. No other examined parameters had any impact on pregnancy subsistence in the researched population whatsoever.
Origem social e desempenho escolar nos anos finais do Ensino Fundamental (2013-2019)
Authors: Ramos da Cruz Scalon Maria Celi , Tavares Júnior Fernando , Alcantara Victor Gabriel
Published: February 2023

Este trabalho propõe uma análise do efeito de fatores sociais no desempenho escolar aferido pelo Sistema Nacional de Avaliação da Educação Básica (Saeb) entre 2013 e 2019. O objetivo é discutir o impacto da origem social nas trajetórias individuais, aqui abordadas através dos dados secundários fornecidos pelo Instituto de Estudos e Pesquisas Educacionais Anísio Teixeira (Inep). Serão discutidas, principalmente, duas perspectivas consolidadas na literatura sobre desigualdades educacionais: uma em relação à conservação e reprodução de posições de origem, o tipo “Escola Reprodutora” e outra em relação aos casos de Escolas que conseguem controlar desigualdades de origem e oferecer condições adequadas ao desenvolvimento dos estudantes, o tipo “Escola Eficaz”. Entre esses dois extremos, que se configuram em categorias analíticas/tipos ideais, contribuímos com um panorama do efeito de fatores sociais ao longo do tempo. Com isso sistematizamos evidências empíricas em relação às desigualdades de resultados escolares e padrões de estratificação educacional.
Adversarial machine learning: the rise in AI-enabled crime
Authors: Sivaram Jahnavi , Narrain Jigisha M , Honnavalli Prasad , Eswaran Sivaraman
Published: February 2023

The rise in frequency and consequence of cybercrimes enabled by artificial intelligence (AI) has been a cause of concern for decades. At the same time, we've seen the development of defensive capabilities. This article examines the mechanics of AI-enabled attacks. These include voice mimicking used for crime, and natural processing algorithms absorbing harmful and offensive human text patterns to create problematic virtual situations. It also looks at shadow models – evasion, infiltration and manipulation of machine-learning models through shadow modelling techniques are on the rise due to their straightforward development methods, allowing the identification of shortcomings in input features, which can cause misclassification by the model. With a special focus on spam filters, their structure and evasion techniques, we look at the ways in which artificial intelligence is being utilised to cause harm, concluding with a final analysis of the Proofpoint evasion case.
Examination of early treatment effects and related biases during the conduct of two UK-wide pragmatic orthopaedic surgical trials: ProFHER and UK FROST
Authors: Knowlson Catherine N. , Brealey Stephen , Keding Ada , Torgerson David , Rangan Amar
Published: February 2023

Aims

Early large treatment effects can arise in small studies, which lessen as more data accumulate. This study aimed to retrospectively examine whether early treatment effects occurred for two multicentre orthopaedic randomized controlled trials (RCTs) and explore biases related to this.

Methods

Included RCTs were ProFHER (PROximal Fracture of the Humerus: Evaluation by Randomisation), a two-arm study of surgery versus non-surgical treatment for proximal humerus fractures, and UK FROST (United Kingdom Frozen Shoulder Trial), a three-arm study of two surgical and one non-surgical treatment for frozen shoulder. To determine whether early treatment effects were present, the primary outcome of Oxford Shoulder Score (OSS) was compared on forest plots for: the chief investigator’s (CI) site to the remaining sites, the first five sites opened to the other sites, and patients grouped in quintiles by randomization date. Potential for bias was assessed by comparing mean age and proportion of patients with indicators of poor outcome between included and excluded/non-consenting participants.

Results

No bias in treatment effect was observed overall for the CI site, or the first five sites, compared with the remaining sites in either trial. An early treatment effect on the OSS was observed for the first quintile of participants recruited to ProFHER only (clinically relevant difference of seven points). Selection bias for age was observed in the ProFHER trial only, with slightly younger patients being recruited into the study. Both trials showed some selection bias for markers of poor prognosis, although these did not appear to change over time.

Conclusion

No bias in treatment effects overall were found at the CI or early sites set-up. An early treatment effect was found in one of the two trials, which was likely a chance effect as this did not continue during the study. Selection bias was observed in both RCTs, however this was minimal and did not impact on outcome.

Cite this article: Bone Jt Open 2023;4(2):96–103.
Images of Inhomogeneous Turbid Media Using Diffuse Photon Density Waves
Authors: O'Leary M. A. , Boas D. A. , Chance B. , Yodh A. G.
Published: February 2023

In this paper we present images derived from measurements of diffuse photon density waves in turbid media. After a brief introduction and description of the experimental set-up, this document is divided into two sections.

In the first, we present an analytic solution for the scattering of diffuse photon density waves by spherical and cylindrical inhomogeneities within turbid media and discuss the application of this solution to systems containing multiple objects and multiple sources. This exact solution is a useful tool for simulating the distortion of a diffuse photon density wave due to simple inhomogeneities. Until recently, simulations of heterogeneous media were achieved by Monte-Carlo methods, finite element analysis, or other time consuming techniques. More recently, Feng et al. [1] presented a perturbative solution for a single, point-like heterogeneity. The exact calculation we present is not limited to small objects, and numerical calculations using this solution are fast compared to Monte Carlo simulations[2]. Finally, we experimentally demonstrate that this analytic solution enables us to fit for the optical and geometric properties of arbitrary spherical and cylindrical objects, and we discuss the detector sensitivity required to characterize such objects.

In the second section we derive images of more general inhomogeneous scattering media. Our method is based on the diffusion approximation, but is not an iterative approach; it is a direct inversion that is exact to first order in variations of the sample absorption. An increase in sensitivity is achieved through the use of multiple-source/single-detector units placed around the turbid medium. In our particular case, each unit consisted of a set of two modulated diffuse light sources phased 180° out of phase with respect to one another, and a single detector located at positions equidistant from each source. In this report we will describe the general theoretical approach, provide experimental evidence of its utility, and discuss potential applications.
Perturbation Calculations of Photon Density Waves Interfering in an Inhomogeneous Tissue-Simulating Medium
Authors: Pogue Brian W. , Patterson Michael S.
Published: February 2023

Analytic calculations have been used to simulate photon density wave interference images of objects within a tissue medium. Various source-detector geometries are examined.
Evaluation of Spatial Variations in the Time and Frequency Dependence of Imaging Operators for Diffusion Tomography
Authors: Graber H. L. , Chang J. , Barbour R. L. , Aronson R.
Published: February 2023

Employing the framework of a perturbation model for optical diffusion tomography, the sensitivity and selectivity attainable from optical time- and frequency-domain, including phased array, measurements, are compared and contrasted. Monte Carlo simulations were used to calculate impulse-response functions in the interior of several homogeneous media. From the results, the impact on detected light due to small localized changes in absorption cross-section were computed. A feature unique to the frequency domain is the ability to qualitatively modify the depth profile of the weight amplitude by employing several sources in a phased array. In the case of single-source transmission measurements, a time-resolved measurement with a short integration time leads to enhanced ability to resolve deep-lying structures, by increasing the weight in deep regions relative to those near the surface. In contrast, as the source modulation frequency is increased in a frequency-domain measurement, the weight amplitude drops off most rapidly in regions farthest from the boundaries, and more slowly in more superficial regions. The significance of these findings for perturbation-based image recovery schemes is discussed.
Optical Coherence Microscopy
Authors: Izatt Joseph A. , Hee Michael R. , Tearney Gary , Owen Gabrielle M. , Swanson Eric , Fujimoto James G.
Published: February 2023

Confocal microscopy has become a standard technique for high resolution optical imaging in many fields1,2. Confocal imaging is conventionally limited to relatively transparent specimens, since image contrast is degraded by light scattering in turbid samples. We have developed a new method for coherent confocal microsopy which uses low-coherence interferometry to enhance optical sectioning in highly scattering media. In optical coherence microscopy (OCM), improved confocal imaging is achieved through high detection sensitivity and high contrast rejection of out-of-focus light. OCM is an adaptation of optical coherence tomography (OCT), which has recently been demonstrated for noninvasive, ten-micron-scale resolution imaging in the eye and other biological tissues3-5. The extension of this technique to confocal microscopy offers the potential for micron-resolution imaging deep into highly scattering media such as skin and endoscopically accessible tissues, and may make possible the development of a new form of noninvasive "optical biopsy."
Low Coherence Interferometry for Imaging Microstructures within Optically Turbid Tissues
Authors: Schmitt J. M. , Knüttel A. , Bonner R. F.
Published: February 2023

The interpretation of optical-coherence tomograms of biological tissues is discussed in the context of our current knowledge of optical propagation in turbid media.
Optical Penetration Depth in Layered Tissues
Authors: Taitelbaum Haim
Published: February 2023

Analytical expressions are derived for statistical measures of the penetration of radiation into two-layered tissues, based on a random-walk model of photon migration. In particular, we study the pigmented upper layer case, which is typical for most biological tissues, where the upper layer is the more absorptive one. Results are presented for the reemitted intensity profile, the averaged path length and for measures of the penetration depth of both re-emitted and internally absorbed radiation. These results are extremely important in medical applications for diagnostic and therapeutic purposes.
Perturgation Theory of Photon Migration in the Presence of a Single Defect
Authors: Feng Shechao , Zeng Fan-An , Chance Britton
Published: February 2023

We present an analytical perturbation analysis to study the sensitivity of diffusive photon flux to the addition of a small shperical defect object in multiple scattering media such as human tissues. As a first simple application of our perturbation method, we derive analytically the photon migration path distributions, and the shapes of the so called “banana” regions in which the photon migration paths are concentrated. We then derive analytically the sensitivity of detected photon flux densities to the inclusion of small spherical defects in the multiple scattering medium, for both single source and two-source configurations, at both steady state (DC) and frequency modulation conditions, and compare the results with Monte Carlo simulations.
Imaging Laser-Heated Cutaneous Chromophores
Authors: Milner T. E. , Anvari B. , Nelson J. S. , Tanenbaum B. S. , Svaasand L. O.
Published: February 2023

Time-resolved infrared images are used to form tomographic reconstructions of laser-heated cutaneous chromophores. In-vitro and in-vivo experiments are reported and discussed.
Absorption and Scattering Properties in a Highly Absorbing Turbid Medium
Authors: Liu H. , Boas D. A. , Beauvoit B. , Rachofsky E. , O’Leary M. A. , Kitai T. , Chance B.
Published: February 2023

The use of NIR spectroscopy to determine, within the diffusion approximation, the absorption and scattering coefficients (μa and μs') of a highly-absorbing turbid medium is very difficult. In this paper, we investigate whether this difficulty results theoretically from the invalidation of the diffusion approximation or technically from the weak light intensity and small signal to noise ratio caused by the high absorption. First, we employ the transport theory in a simplified form to predict the ratio μa/μs' when the diffusion approximation becomes invalid. We show that the diffusion theory breaks down when the ratio of μa/μs' is equal to ~1/10. This implies that the diffusion approximation is still valid theoretically for a very high absorbing organ, such as liver. Then, as an example of NIR spectroscopy with highly absorbing tissue, we present in vivo hemoglobin saturation studies on cuffed human forearms using continuous, amplitude modulated, and pulsed light.
Near-Infrared Optical Spectroscopy of Tissues Using an LED Frequency Domain Spectrometer
Authors: Gratton Enrico , Fantini Sergio , Franceschini Maria Angela , Fishkin Joshua B. , Maier John S.
Published: February 2023

We present a light emitting diode (LED) based spectroscopic method for application in highly scattering materials. Using an LED as a light source, frequency domain measurement and the diffusion model of photon migration, we measured the absorption spectrum of a chromophore (methylene blue) suspended in a highly scattering medium (1.54% solids content Liposyn fat emulsion). The resulting spectrum agrees both qualitatively and quantitatively with standard spectropho-tometric measurements obtained without the scattering. Finally, we enumerate reasons why LED-based frequency-domain techniques are very appropriate for medical applications.
Optical Imaging for Medical Diagnostics Using Femtosecond White Light
Authors: Berg Roger , Andersson-Engels Stefan , Klinteberg Claes af , Svanberg Sune , Jarlman Olof
Published: February 2023

Femtosecond white light has been used for simultaneous multi-spectral time-resolved tissue-phantom transillumination. Contrast enhancement has been studied using differential absorbers located inside the tissue phantoms. Measurements on female breast in vitro are also presented.
Resonant Recurrent Scattering Between Dielectric Spheres
Authors: van Tiggelen Bart A. , Lagendijk Ad
Published: February 2023

We give an overview of our investigations concerning the role of recurrent scattering from pairs of dielectric spheres in a transport This phenomenon is intimately related to Induced Dipole-Dipole coupling familiar from atomic physics. We show numerically how dynamic and stationary transport characteristics are modified by recurrent scattering events.
Wave Automaton for Wave Propagation in Random Media
Authors: Sebbah Patrick , Sornette Didier , Vanneste Christian
Published: February 2023

We present an original numerical approach for investigation of time-dependent wave propagation in random media. We review different results in 2D, including subdiffusive regime characterization, NDE in the multiple scattering regime and Anderson localization in presence of a nonlinear local gain.
Statistical Properties of Waves Propagating in a Random Environment
Authors: Cwilich Gabriel
Published: February 2023

A diagrammatic approach to evaluate the statistics of the wave intensity in the coherent propagation of light in a random medium is considered; I describe a technique to investigate the underlying random walks by mapping them into spin systems.
High Resolution IntraArterial Imaging with Optical Coherence Tomography
Authors: Brezinski Mark E. , Weissman Neil , Tearney Gary J. , Boppart Stephen A. , Bouma Brett , Swanson Eric , Fujimoto James G. , Southern James F.
Published: February 2023

Current cardiovascular imaging technologies lack the resolution to accurately identify patients at high risk for acute myocardial infarction and sudden death. This study assesses the feasibility of a recently developed imaging technology, optical coherence tomography(OCT), to provide high resolution imaging of coronary microstructure. Imaging of in vitro human tissue was performed, demonstrating its ability to identify high risk coronary plaques. Its performance was also directly compared with high frequency ultrasound (IVUS), the current clinical technology with the highest resolution. The 16 micron axial resolution of OCT allowed a far superior analysis of plaque microstructure compared with the 110 micron resolution of IVUS. OCT represents an attractive technology for high resolution intravascular imaging due to its high resolution, high contrast, and ability to be integrated with intravascular catheters.
Optical Coherence Tomography of Embryonic Morphology During Cellular Differentiation
Authors: Boppart Stephen A. , Tearney Gary J. , Bouma Brett E. , Fujimoto James G. , Brezinski Mark E.
Published: February 2023

Improved imaging of morphological changes has the potential of offering new insight into the complex process of embryonic development. Optical coherence tomography (OCT), is a new imaging technique for performing in vivo cross-sectional imaging of architectural morphology by measuring backscattered infrared light. This study investigates the application of OCT for imaging developing structure in Xenopus laevis (African frog) and Brachydanio rerio (zebra fish), two developmental biology animal models. Images are compared to corresponding histological preparations. Cross sectional imaging can be performed and structural morphology identified at greater imaging depths than possible with confocal and light microscopy. Repeated OCT imaging may be performed in vivo in order to track structural changes throughout development. Imaging in vivo microscopic embryonic morphology with OCT is a fundamental biological research application for the study of genetic disease.
A Multichannel Approach To Coherent Optical Imaging Through Turbid Media
Authors: Gleyzes P. , Saint-Jalmes H. , Boccara A.C.
Published: February 2023

We present two experimental set-ups used for imaging through scattering media : a Mach-Zehnder interferometer, working in transmission, and a Nomarski microscope, working in reflection. Both systems, equipped with an array of detectors, take advantage of multichannel lock-in detection schemes.
Heterodyne Measurement of Wigner Phase Space Distributions in Turbid Media
Authors: Wax A. , Thomas J. E.
Published: February 2023

We demonstrate a method for heterodyne detection of Wigner phase space distributions in turbid media, with a dynamic range of 13 orders of magnitude for 1 mW input and local oscillator beams.
The effect of overlying tissue on NIR light propagation in neonatal brain
Authors: Okada Eiji , Delpy David T.
Published: February 2023

The effect of the layered surface tissue of the neonatal head on near infrared spectroscopy (NIRS) measurement of brain oxygenation has been investigated by Monte Carlo simulation. Four different cylindrical models have been adopted in order to investigate the effect of the clear cerebrospinal fluid (CSF) layer surrounding the brain on the light propagation. The simplest is a four layered model without a clear CSF layer whilst the most sophisticated model consists of five layers including the clear layer containing slots imitating the sulci in the brain. The fractional optical pathlength in each layer and spatial sensitivity profiles are predicted to examine the contribution of each layer to the NIRS signal. The clear CSF layer was found to affect the light propagation in the neonatal head, causing the light to follow the CSF boundary. This phenomena reduces the contribution of absorption changes in the white matter to the NIRS signal. However the contribution of the brain exceeds 75 % at an optode spacing of 50 mm in the neonatal head, a much greater contribution than observed for the adult brain. The spatial sensitivity around the sulci increases slightly, but the sulcus structure does not significantly affect the optical pathlength and general trend of the spatial sensitivity profile.
An optoelectronic cross-correlator using a gain modulated avalanche photodiode for measurement of the tissue temporal point spread function.
Authors: Kirkby David R. , Delpy. David T.
Published: February 2023

A small and relatively inexpensive optoelectronic cross-correlator, using an avalanche photodiode (APD) detector and without any moving parts has been developed to measure the temporal point spread function (TPSF) of light in tissue. From the TPSF, it is in principle possible to determine the optical properties of the tissue. Currently a temporal response of 275 ps full width half maximum (FWHM) has been achieved. Measurements of the TPSF of a tissue phantom using a synchroscan streak camera and the cross-correlator show excellent agreement, although the achievable signal to noise ratio currently limits the ability of the cross-correlator to detect the low intensity sections of a TPSF.
Time-Resolved Imaging of Solid Tissue Phantoms Using a Perturbation Model
Authors: Hebden Jeremy C. , Arridge Simon R.
Published: February 2023

Measurements of the time-dependent intensity of transmitted light through a highly scattering tissue phantom have been compared with an analytical model which describes the sensitivity of that intensity to localized changes in optical properties. A least-squares fitting procedure is employed to investigate the accuracy with which the model can predict the true displacement between a single embedded inhomogeneity and the line-of-sight across the phantom. The embedded object has twice the scatter and absorption coefficient of the surrounding medium. A further fitting procedure was used to derive the amplitudes of the measurement perturbations as the line-of-sight is translated towards the inhomogeneity. Results show that the diffusion perturbation amplitude provides inherently greater spatial resolution than the absorption perturbation amplitude.
Review of Adaptive Optics Projects for the Large Telescopes
Authors: Ridgway Stephen T.
Published: February 2023

It is now widely believed that adaptive optics will markedly impact the performance of optical telescopes. However, with few exceptions, astronomers have not invested great effort in adaptive optics. Of the many 2-4 meter class telescopes in the world, none has been systematically retrofitted with adaptive optics for astronomical research. At present, 8 telescopes in the 8-10 meter class are funded and under construction. None yet has a detailed implementation plan for adaptive optics, and only one observatory is close to such a plan.
The role of adaptive optics in long-baseline interferometry
Authors: Greenaway A H
Published: February 2023

To obtain, at optical frequencies, even crude images of some stars of most spectral types an instrument of several hundred metres in diameter is required [1]. A single optical telescope of this diameter is unlikely to be constructed in the foreseeable future, either on the ground or in space. Thus to obtain images of the surfaces of a significant number of stars other than the sun an interferometric instrument, consisting of several separate telescopes, will need to be used. The processes by means of which an image may be synthesized from such an instrument have been reviewed recently [2]. Here the use of adaptive optics to improve the sensitivity of such an array will be considered.
Corrected field of view and resolution in multiple adaptive mirror systems
Authors: Shamir Joseph , Crowe Devon G.
Published: February 2023

Using a layered atmospheric turbulence model, it is shown that substantial extension of the compensated field of view is possible by employing a number of adaptive mirrors and guide stars. In large astronomical telescopes additional extension of the compensated field of view can be achieved at the expense of effective aperture size available for diffraction limited resolution.
Application of Spatial Filtering to Ground-Based Interferometry
Authors: Prasad Sudhakar , Loos Gary
Published: February 2023

Interferometric, or aperture-synthesis, imaging of ever fainter objects requires ever larger aperture sizes. However, for ground-based interferometry, large aperture sizes entail a large decorrelation – and an accompanying loss of sensitivity – as a result of the atmospheric turbulence.
Large Telescope Adaptive Optics Requirements for Astrophysics and Space Missions
Authors: Chen Chien-Chu , Levine B. Martin , Meinel Aden B. , Meinel Marjorie P. , Sevaston George , Redding David C.
Published: February 2023

Future adaptive optics systems will be needed to accomplish missions in diverse applications ranging from astrophysics to optical communications, and from ground-to-space power transmission. These missions support corresponding programs at the Jet Propulsion Laboratory (JPL) each with unique requirements to be discussed in this paper.
Compensation Of Static Atmospheric Turbulence With Far-Field Optimization
Authors: Mehta Naresh C. , Allen Clinton W.
Published: February 2023

The angular resolution of large ground-based telescopes is limited by local atmospheric seeing. If effects of atmospheric turbulence can somehow be compensated, one can achieve diffraction-limited imaging on ground. Steady progress has been made over the past two decades in adaptive optics technology which promises to provide real-time turbulence compensation.
Results of Adaptive Correction of Amospheric Piston and Tilt Errors at the Multiple Mirror Telescope
Authors: Lloyd-Hart M. , Dekany R. , Wittman D. , Sandler D. , McLeod B. , Angel R. , McCarthy D.
Published: February 2023

An objective of our adaptive optics research at the 7-m Multiple Mirror Telescope (MMT) is to investigate ways of reconstructing wavefront errors accurately over large spatial scales. Correction of tilt error across and piston errors between each of the six 1.8-m diameter segments of the MMT is sufficient to recover the full diffraction-limited resolution at 2.2 μm of 0.06 arcseconds full width at half maximum1.
A Neural Network to Control Low-Order Wavefront Distortion at the SOR 1.5-Meter Telescope
Authors: Barrett T. K. , Sandler D. G. , Fugate R. Q. , Ellerbroek B. A. , Donovan M. T. , Higgins C. H. , Spinhirne J. M.
Published: February 2023

Simulations and earlier off-line experimental data suggest1,2 that a wavefront sensor based on an artificial neural network processor may provide a simple way to measure low-order wavefront distortion in an astronomical telescope. The neural network is trained to estimate the low-order modes from focused images of natural or artificial guide stars. In this paper we report the status of further simulations and experiments to implement and test a network for wavefront control on the SOR 1.5-meter telescope.
Real-time Fourier transform image analysis for measuring atmospheric phase errors over large apertures
Authors: Dekany R. , Lloyd-Hart M. , Sandler D. , Angel J. R. P.
Published: February 2023

Most existing techniques to measure wavefront aberrations rely on single or double integrations of local tilt or curvature. These techniques forfeit accuracy when applied to large apertures, when the number of subapertures needed to span the pupil becomes great. Since a natural star must be used to sense overall tilt, it is useful to consider direct interference methods which exploit the spatial coherence of starlight to make large scale phase measurements as well. Phase information is contained directly in the interference speckles of the far field image. Recently Angel et. al.1 and Lloyd-Hart et. al.2 have demonstrated the use of artificial neural nets to analyze speckle images for phase. Here we present the theory behind an approach to reconstruct pistons in real time using data obtained by Fourier transforming the image-plane interference pattern. The underlying idea behind the approach draws on methods developed for long-baseline interferometry3,4,5.
A Phase Diversity Wavefront Sensor For Adaptive Optics Applications
Authors: Duncan A.L.
Published: February 2023

Segmented aperture optical systems require phasing sensors to maintain diffraction limited performance. Many types of sensors have been proposed and investigated. Of particular interest for passive imaging applications are phasing sensors capable of extracting the segment phasing information from complex extended scenes during imaging and performing real-time corrections in closed loop form of the optical system. The optical system may be a phased array or segmented primary type.
Atmospheric Turbulence Compensation Using Self-Referenced Binary Holographic Interferometry
Authors: Ma S. , Guthals D. , Hu P. , Campbell B.
Published: February 2023

A technique to perform atmospheric compensation of ground-based telescopes using self-referenced interferometry with a binary holographic recording medium is analyzed for a 1.5m aperture. Substantial image correction is predicted with an artificial guidestar reference.
Ultrafast Er fiber laser amplified to an average power of 5.5 W in an Yb fiber amplifier
Authors: Galvanauskas A. , Cho G. C. , Fermann M. E. , Stock M. L. , Harter D.
Published: February 2023

We demonstrate the amplification of femtosecond Raman-shifted pulses from an Er fiber laser to a pulse energy of 100 μJ and an average power of 5.5 W in an Yb fiber chirped pulse amplification system.
RTP as a Q-switch for high repetition rate applications
Authors: Lebiush E. , Lavi R. , Tsuk Y. , Angert N. , Gachechiladze A. , Tseitlin M. , Zharov A. , Roth M.
Published: February 2023

We report on a novel large aperture RTP-based electro-optic Q-switch exhibiting high damage threshold, low insertion losses, excellent thermal stability and negligible piezoelectric ringing at repetition rates up to 75 kHz. 4.6 W average output power has been achieved at 75 kHz for a diode end-pumped Nd:YVO4 laser with 31% light to light and 40% slope efficiencies.
Quantifying Color Appearance Visually and Instrumentally
Authors: Billmeyer Fred W.
Published: February 2023

How to obtain accurate visual or instrumental measurements of color appearance is a largely unsolved problem of color science. Ideally, one would like to quantify our everyday perception of the appearance of object colors in complex scenes. As this review will show, we are far from achieving this goal.