bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure of the transmembrane protein 2 (TMEM2) ectodomain and its lack of hyaluronidase activity
Authors: Niu Muyuan , McGrath Molly , Sammon Douglas , Gardner Scott , Morgan Rhodri Marc , Bubeck Doryen , Hohenester Erhard
Published: February 2023

Background: Hyaluronic acid (HA) is a major polysaccharide component of the extracellular matrix. HA has essential functions in tissue architecture and the regulation of cell behaviour. HA turnover needs to be finely balanced. Increased HA degradation is associated with cancer, inflammation, and other pathological situations. Transmembrane protein 2 (TMEM2) is a cell surface protein that has been reported to degrade HA into ~5 kDa fragments and play an essential role in systemic HA turnover.

Methods: We produced the soluble TMEM2 ectodomain (residues 106-1383; sTMEM2) in human embryonic kidney cells (HEK293) and determined its structure using X-ray crystallography. We tested sTMEM2 hyaluronidase activity using fluorescently labelled HA and size fractionation of reaction products.

Results: Our crystal structure of sTMEM2 confirms a remarkably accurate prediction by AlphaFold. sTMEM2 contains a parallel β-helix typical of other polysaccharide-degrading enzymes, but an active site cannot be assigned with confidence. A lectin-like domain is inserted into the β-helix and predicted to be functional in carbohydrate binding. A second lectin-like domain at the C-terminus is unlikely to bind carbohydrates. Unexpectedly, we were unable to observe any HA degradation by sTMEM2. Our negative results set an upper limit for    kcat of approximately 10-5 min-1.

Conclusions: Although sTMEM2 contains domain types consistent with its suggested role in TMEM2 degradation, its hyaluronidase activity was undetectable. HA degradation by TMEM2 may require additional proteins and/or localisation at the cell surface.
Students with Dyslexia in Universities in Poland – Description of the Legal Situation and Good Practices
Authors: Ignaciuk Michalina , Łockiewicz Marta
Published: February 2023

The aim of this article was to analyse the currently functioning system of support for students with dyslexia at state universities in Poland and to identify and assess goodpractices that are already being implemented. The research method used was desk research (reviewing both formal and informal documents) and included university websites andnational and local legal regulations. The results showed that only nine (15%) state universities in Poland introduced concrete forms of support for the students with dyslexia and the faculty, such as exam concessions (six universities), consultations with a specialist (for students: six universities; for teachers: five universities), and provision of information and educational materials (nine universities). A comparison of the Polish support system for students with dyslexia with that of the UK resulted in a list of recommendations, including the extension of the examination time by 25% of the basic time, the assessment of written assignments solely on the basis of content and not on the correctness of spelling and changes in the format of an exam (from written to oral).
The preparation of a selected parents population to take care of the child with asthma
Authors: Olszańska Teresa , Witanowska Jolanta , Jarecka Beata
Published: February 2023

Aim of the Study. Asthma is considered as an increasingly frequent chronic disease affecting children and adults. Both the treatment processes and the overall progress in child treatment are hugely dependent on healthcare quality, as well as parents’ engagement.
Material and Methodology. The aim of the research was to look into the major problem concerning daily care and raising the awareness among parents of asthma in children. A questionnaire was handed out to parents of children diagnosed with asthma. The research was conducted at the Provincial Centre of Paediatrics “Kubalonka” in Istebna. The survey group consisted of 103 parents. The correlation and differences between groups were defined using the ANOVA analysis. The statistical analysis was conducted with STATISTICA 10.0.
Results. The findings of the study show that parents have sufficient knowledge about asthma and they tend to take the right measures aimed at eliminating allergens. Yet, there is a need to broaden the parents’ knowledge in the following fields: observation, early diagnosis, procedures in case of an exacerbation of the disease, as well as performing some breathing exercises.
Empathy and assertiveness of nurses providing care to patients with psychological and somatic disorders
Authors: Motyka Helena , Motyka Katarzyna
Published: February 2023

Introduction. It seems that providing care to mentally ill patients requires more developed interpersonal skills than helping patients without mental disorders. Therefore, one might expect that psychiatric nurses would be more empathic and assertive than their colleagues from other wards.

Aim. The aim of the study was to assess empathy and assertiveness levels of nurses working with patients with mental and without mental disorders.

Material and methods. The study covered 120 nurses including 60 psychiatric nurses and 60 nurses from other wars. Empathy levels were measured using Davis’ IRI test, whereas assertiveness was determined using the Assertiveness Map developed by M. Król-Fijewska.

Results. No differences were found between empathy and assertiveness levels of nurses working on psychiatric and non-psychiatric wards. A positive and statistically significant correlation (p=0.01) was discovered between the nurses’ age and their ability to adopt the other person’s point of view.

Conclusion. Nurses’ empathy and assertiveness is unrelated to the type of ward they work on. Cognitive empathy of nurses increases with age – especially their ability to look at things the way patients do. Quality of nursing care could be improved by teaching nurses about communicating with patients. Such training sessions could be especially aimed at inexperienced nurses.
The functional status of patients undergoing surgical treatment for discopathy of lumbar spine
Authors: Kołpa Małgorzata , , Zawiślak Elżbieta , Jurkiewicz Beata , Grochowska Aneta
Published: February 2023

Introduction. Spinal discopathy due to the recurrent nature of pain is one of diseases which influence the deterioration in the functional status.

Aim. The objective of the paper was to assess the severity of pain and functional status of patients with lumbar spine pain syndrome in the period before and after surgery.
Material and Methodology. The study included 100 subjects undergoing surgical treatment for discopathy of lumbar spine. In order to check the effects of surgery, VAS scale, RMDQ questionnaire and self-made survey questionnaire were used. Anthropometric measurements were also performed to determine BMI and WHR. The studies were carried out before operation and repeated 6 months after surgery.
Results. The sum of pain intensity according to VAS scale in the lumbar spine area, the right and left lower limb was 13.18 (± 3.25 pts) vs. 6.08 (± 2.53 pts) before and after surgery, respectively. Before surgery, the patients achieved on average 11.47 (±4.56 pts) in RMDQ scale, whereas after treatment this indicator decreased, and the subjects obtained on average 7.31 (±3.30 pts).
Conclusion. After surgical treatment, the functional status of patients improved and the intensity of pain decreased.
Os ingressantes das profissões jurídicas: um estudo de trajetórias
Authors: Visser Ricardo , Siqueira Gustavo
Published: February 2023

O presente artigo tem como principal propósito apresentar os resultados de uma pesquisa com oito entrevistados, realizada com profissionais do Direito, cuja característica principal é a ausência de antecedentes familiares em profissões com curso superior. Primeiramente buscou-se uma definição conceitual e metodológica da pesquisa qualitativa, bem como seu enquadramento amostral, e em seguida adentrou-se na caracterização dos perfis encontrados a partir de suas trajetórias. A pesquisa delineou três variáveis de interesse dentro do questionário semiestruturado utilizado: a dimensão familiar, a educacional e a profissional. Na seara familiar, investigou-se como o acesso ao curso e às profissões com nível superior comumente envolve certo distanciamento em relação à trajetória dos pais. Também pesquisamos as principais dificuldades educacionais narradas pelos entrevistados. Em seguida, perquirimos suas trajetórias no ensino superior, procurando entender de maneira articulada os obstáculos materiais e culturais narrados. Assim, tentamos desenhar os limites e possibilidades dos ingressantes dentro das profissões jurídicas. Conclui-se que o conjunto de dificuldades narradas não pode ser compreendido de maneira fragmentada, uma vez que produzem efeitos agregados para o público. Por fim, procuramos compreender as maneiras de inserção profissional. Encontramos duas maneiras gerais: o autônomo, que congrega tanto os que abrem seus próprios escritórios quanto os assistentes jurídicos paralegais, e os empregados de carteira assinada em órgãos privados e públicos. Verificou-se que não há uma única forma de inserção profissional, uma vez que os ingressantes não se encontram necessariamente em condição de precariedade laboral. Não que ela não exista, mas não se configura uma condição geral de todos os entrevistados e parece estar mais próxima dos assistentes jurídicos paralegais, que ainda buscam passar no exame da Ordem dos Advogados do Brasil. Embora os perfis não esgotem esse estrato social, o intento foi desenhar suas principais dificuldades e conquistas, demonstrado o acesso estratificado às carreiras jurídicas no Brasil.
Bloom’s Taxonomy Revision-Oriented Learning Activities to Improve Procedural Capabilities and Learning Outcomes
Authors: Adijaya Made Aryawan , Widiana I Wayan , Parwata I Gusti Lanang Agung , Antara I Gede Wahyu Suwela
Published: February 2023

The implementation of learning activities in schools has not provided opportunities or encouragement for students in developing their procedural knowledge. This research aimed to test the effectiveness of developing Bloom’s Taxonomy revision-oriented learning activities to grade IV elementary learners’ procedural knowledge capabilities and learning outcomes. This research used quasi-experiment with a quasi-experimental design which consisted of a posttest-only control design. The population of this study was sixth-grade students of 9 schools with an overall number of 229 students. The sample in the study was 50 students, there were 26 students from the experimental class and 24 students from the control class. A test method with 10 question items was used as a data collection method. The data analysis methods and techniques used were quantitative descriptive analysis and inferential statistical analysis. Then the data were analyzed using the MANOVA test assisted by the IBM SPSS Statistics 21.0 program. The hypothesis test results showed a significance value of .000 (Sig<.05). It can be concluded in procedural capabilities and learning outcomes between groups of students there is a significant difference from following learning by implementing Bloom's Taxonomy Revision oriented learning activities with the experimental and control group.
How to breathe
Authors: Power Camilla
Published: February 2023

For Marx, all forms of economics could be reduced to “an economics of time”. To restore a sustainable rhythm to our planet, our lifeways and economy, we need to decolonize time. The first part of this essay sketches a history of capitalism as robbery: ever tighter control of time yielding greater economic exploitation and inequality. The second part asks how we could reorganize and redistribute time. What can indigenous and egalitarian societies teach us today about the passage of time? What biological and cultural resources do we have for slowing down the rhythms of our economy and redistributing time? The evolution of women’s reproductive cycles and the lunar calendars shared by world religions give evidence for a deep time human lunar ecology.
Reflections on the economics of socialism
Authors: Rogers Nick
Published: February 2023

Socialist economic management should be reconceptualized. Economic planning conceived as the ex ante allocation of everything that is to be produced in any given production cycle does not capture how any organization, let alone a whole economy, works. Planning should involve preparing in advance to respond flexibly to a range of possible eventualities. The way corporations, such as Walmart and Amazon, manage their supply chains points towards how non-commodity production and non-market allocation could work efficiently, while responding flexibly to the consumers of a socialist economy. Openness, sharing of information, and transparency about the use of labor-time in the economy (we should take Marx’s discussion of “labour certificates” seriously) are critical to overcoming the fragmentation of decision-making that is a key feature and a key weakness of a capitalist economy. A system of socialist goal-directed economic coordination could outperform capitalism in the provision of goods and services, while enabling economic decision-making to be decentralized and political power dispersed throughout society, so as to make a reality of the “withering away of the state”.
Universal basic income: An idea whose time has come or just another mechanism to grease the wheels of capitalism?
Authors: Fitzpatrick Pamela
Published: February 2023

Universal basic income (UBI) is a system where everyone in a community is given a regular fixed amount of money from government intended to meet basic needs and free from any conditionality. Such a system is cheap and easy to administer as there is no means testing or checks on conditionality. There are a growing number of trials across the world and increasing support for such a scheme in the UK. A decade of austerity policies in the UK followed by the onset of the COVID-19 pandemic has heightened the views of some that UBI would not only address the issue of poverty and low-paid work but would serve as a response to growing automation in the workplace. It might also increase the bargaining power of workers who would be less worried about losing their job if they had the cushion of UBI.
Photon Density Wave Diffraction Tomography
Authors: Hielscher Andreas H. , Tittel Frank K. , Jacques Steven L.
Published: February 2023

It is demonstrated that diffraction tomography, an imaging technique which is usually applied with ultrasound waves, can also be used with photon density waves. Resolution in the sub-centimeter range, depending on the optical properties, can be expected.
Frequency-Domain Photon Migration in Turbid Media
Authors: Tromberg Bruce J. , Madsen Steen , Chapman Curtis , Svaasand Lars O. , Haskell Richard C.
Published: February 2023

An analytical model is presented for the propagation of diffuse photon density waves in turbid media. The frequency- and wavelength- dependence of photon density waves are measured using Frequency-domain Photon Migration (FDPM). Media optical properties, including absorption, transport, and fluorescence relaxation times are calculated from experimental results.
Micron-resolution Optical Coherence Tomography of the Human Eye
Authors: Hee Michael R. , Izatt Joseph A. , Huang David , Swanson Eric A. , Lin Charles P. , Schuman Joel S. , Puliafito Carmen , Fujimoto James G.
Published: February 2023

We have developed a new technique for micron scale resolution cross-sectional imaging in biological systems called Optical Coherence Tomography (OCT)1,2 In OCT, low-coherence optical interferometry3,4 is used to resolve the position of reflective or optical backscattering sites within a sample. Two-dimensional tomographic images of a thin, optical slice of tissue may be obtained with 10 μm longitudinal and lateral resolution. Narrowband optical heterodyne detection achieves a sensitivity to reflected light as small as 10-10 of the incident optical power. OCT is non-contact, non-invasive, and has superior resolution to conventional clinical ultrasound. Unlike scanning laser ophthalmoscopy and scanning laser tomography, the optical sectioning capability of OCT is not restricted by the pupil-limited numerical aperture of the eye or ocular aberrations. OCT may be implemented in a compact, low-cost, fiber-optic based interferometer that is easily coupled to existing ophthalmic instrumentation. We demonstrate high-speed, in vivo OCT imaging in both the anterior and posterior eye.
Imaging through Scattering Media Using Pulsed Homodyne Detection
Authors: Beck M. , Anderson M. E. , Raymer M. G.
Published: February 2023

In this paper we demonstrate high resolution imaging of a target embedded in a scattering medium using a pulsed laser source. The imaging is performed by interfering the light emerging from the scattering medium with a 200 fs duration pulsed local oscillator beam, and detecting the interfered light with a balanced homodyne detector. We show that the data collected by our detector can be analyzed in two ways. One method strongly suppresses the detection of scattered light emerging from the medium, leaving almost exclusively the ballistic (unscattered) component of the signal. Using the other data analysis technique, both the scattered and ballistic components of the signal are readily detected. This shows that despite the fact that coherent (homodyne) detection is used, the system can be optimized for the detection of either coherent (unscattered) or incoherent (scattered) light.
Imaging of Turbid Media with a Spatial Filter
Authors: Wang Lihong , Hielscher Andreas H. , Jacques Steven L. , Stephens Dawn V. , Tittel Frank K.
Published: February 2023

A buried object inside a turbid medium was imaged using a continuous-wave laser of 5-mW output power and a spatial filter. The spatial filter consists of a lens of 4-cm focal length and a pinhole of 10-μm diameter. A lock-in amplifier was used to reduce the noise. An absorbing rod of 2-mm diameter was buried in the center of a 5-cm thick cuvette filled with polystyrene spheres solution. The object was detected with a contrast of 99% when the turbid medium was 20 mean free path thick, and 10% when 30 mean free path thick.
Surface Intensity Profiles for Optical Propagation in Random Media
Authors: Lisyanky A. A. , Livdan D. , Li J. H. , Cheung T. D. , Genack A. Z.
Published: February 2023

The time-dependent intensity profile of photons propagating in a random media with reflective boundaries is calculated. Excellent agreement is found between theoretical calculations and measurements of transmission and surface intensity profiles in samples with different surface reflectivities. These results allow us to determine the coherent penetration depth and the optical transport mean-free path are obtained.
Application of Probability of n Scatterings of Light Passing through and Idealized Tissue Slab in Breast Imaging
Authors: Wang Lihong , Jacques Steven L.
Published: February 2023

Based on the probability of a given number of scatterings for photons transmitted through a tissue slab with a unity anisotropy factor, the minimum number of scatterings required for optical imaging of tissues in the transmission mode was estimated. For breast tissue imaging with visible or near infrared light, ballistic imaging is possible only for thicknesses less than 42 mean free paths, which is 0.14 cm for breast adipose tissue at 700 nm wavelength (scattering coefficient is 300 cm–1). For a 5-cm thickness, at least 1100 scattering events must be allowed to receive on average a single transmitted photon from 10-18 input photons (about 1-J visible light). Monte Carlo simulations have shown that the anisotropy of traveling direction of photons after i scatterings decays exponentially with i. The photons that are launched in the same direction will travel practically isotropically after 3/(1–g) scatterings, where g is the anisotropy factor of the tissue. For the breast adipose tissue with g equal to 0.97, 3/(1–g) is 100.
Regularized Progressive Expansion Algorithm for Recovery of Scattering Media from Time-Resolved Data
Authors: Zhu Wenwu , Wang Yao , Graber Harry L. , Barbour Randall L. , Chang Jenghwa
Published: February 2023

A principal difficulty encountered in dealing with highly diffused signals is that the inverse problem is ill-posed and often underdetermined. A progressive expansion (PE) algorithm has previously been reported, which has proven to be quite effective in circumventing the underdetermined nature of the inverse problem. However, the PE approach is sensitive to noise. Propagation of errors can become especially severe when evaluating regions deep beneath the surface. Here we describe results of using a Regularized PE (RPE) algorithm, which is shown to exhibit improved stability. The RPE algorithm has been applied to time–resolved data calculated from a perturbation The media tested include isotropically scattering slabs containing one or two compact absorbers at different depths below the surface. The data were corrupted by additive noise with varying strength. Compared to the original PE algorithm, the RPE algorithm has yielded more accurate and stable reconstructions under the same noise level.
Theoretical and Experimental Investigations of Elastic Scattering Spectroscopy as a Potential Diagnostic for Tissue Pathologies
Authors: Boyer James , Mourant Judith R. , Bigio Irving J.
Published: February 2023

The spectral distribution of the diffuse reflectance of five sizes of polystyrene microspheres has been measured with an elastic scatter spectrometer designed for optical biopsy of living tissue. The microsphere sizes are representative of the suspected scattering centers in living tissue. The experiment data are discussed and interpreted in the framework of Mie scattering theory and Monte-Carlo transport analysis. Present results support the assertion that Mie theory is necessary to describe the spectral features of elastic scatter spectroscopy in tissue.
Resolution of Time Resolved Breast Transillumination
Authors: de Haller E. B. , Depeursinge C.
Published: February 2023

The resolution of the time resolved breast transillumination has been investigated both theoretically and experimentally. The resolution limit is associated to the size of the smallest object visible on an image or image quality index which depends on the image parameters as the transfer function, the contrast and the noise, and it has been determined on Monte-Carlo simulation results as well as in vitro measurements on breast samples. The noise, both photonic and anatomical has been found as a limitating factor of the resolution.
Imaging through Highly Scattering Media with a Novel Upconverting Time Gate
Authors: Faris Gregory W. , Banks Michael
Published: February 2023

We demonstrate a new upconverting time-gate suitable for two-dimensional imaging at wavelengths longer than 1 μm where scatter is typically reduced. Image amplification is obtained when using a difference frequency upconverting time gate.
Achievable Image Resolution Using Non-Diffuse, Multiply Scattered Light
Authors: Moon J. A. , Reintjes J.
Published: February 2023

Starting from the integral formulation of radiative transfer theory, we present a calculation of the intensity and direction of light traversing a multiply scattering medium in the isotropic scattering case for pulsed point source illumination. From these calculations we examine the point-spread-function as a function of detector integration time and sample thickness when the diffusion approximation is not valid. We show that image resolution better than the diffusion limit is theoretically possible using multiply scattered light for samples thinner than about 35 scattering lengths. Monte Carlo simulations are used to extend these results to the anisotropic scattering case.
Statistics of the Intensity of Optical Waves in Random Systems
Authors: Kogan Eugene , Baumgartner Rene , Berkovits Richard , Kaveh Moshe
Published: February 2023

Statistics of coherent radiation propagating in a random medium is analyzed in the framework of diagram technique. The distribution function for radiation intensity is calculated and it is shown, that only for small values of argument the distribution function is simple exponential, as predicted by Rayleigh statistics. For larger values of intensity the distribution function differ drastically from the simple exponential, and the asymptotical behavior is a stretched exponential. The results obtained are confirmed by numerical simulations.
Size Effect in Scattering from a Disordered Media
Authors: Freilikher V. , Kaveh M. , Pustilnik M. , Yurkevich I.
Published: February 2023

Scattering from the bounded random media with volume and surface disorder is studied theoretically. We predict the existence of enhanced scattered peaks caused by degenerated time-reversal symmetry in systems with discrete spectrum.
Multiple Scattering and Enhanced Backscattering Effects for Flat Substrates with Small Protuberances
Authors: Moreno F. , Saiz J. M. , González F.
Published: February 2023

Multiple scattering and enhanced backscattering effects are analyzed for a simple scattering system consisting on a flat substrate with two small spherical scatterers.
Accurate Analysis of Coherent Backscattering Revealing Recurrent Scattering of Light in Disordered Media
Authors: Wiersma Diederik S. , van Albada Meint P. , Lagendijk Ad
Published: February 2023

Weak localization or coherent backscattering is a general effect for waves scattered by a disordered medium. It is an interference effect that survives over length scales much larger than the mean free path, and arises from the time reversal symmetry of the wavelets scattered in the backscattering direction. In the exact backscattering direction, counter propagating wavelets will interfere constructively, while sufficiently far away from this direction phase differences wash out the interference effect. The result is a cone of enhanced backscattering which has a width of the order of λ/ℓ, where λ is the wavelength and ℓ is the (transport) mean free path.
Time-Reversal and Reciprocity Principle Breaking in Weak Localization of Light
Authors: Maynard R. , Martinez A. S.
Published: February 2023

The enhancement factor of the backscattering cone in disordered media, can be assigned to the reciprocity principle. In the context of weak localization of light, the destruction of the backscattering cone can be accomplished by applying a magnetic field in an magnetic-optically active random medium. The time-reversal symmetry breaking and the reciprocity principle breaking is discussed and exemplified using Rayleigh multiple scattering.
Biomedical Diagnostics Using Optical Coherence Tomography
Authors: Sergeev Alexander M. , Gelikonov Valentin M. , Gelikonov Grigory V. , Feldchtein Felix I. , Gladkova Nathaly D. , Kamensky Vladislav A.
Published: February 2023

The progress in creating compact, fast-scanning OCT devices and their use in biomedical research and clinical diagnostics is reported. The results of OCT applications in dermatology, ophthalmology, neurobiology and internal organ studies are presented to demonstrate capabilities and requirements for further development of the method.
Optical Coherence Tomography as a Biomedical Monitor in Human Skin
Authors: Milner Thomas E. , Davé Digant , Chen Zhongping , Goodman Dennis M. , Nelson J. Stuart
Published: February 2023

Skin is not only the largest organ in the human body but also serves to protect and mediate interactions with diverse mechanical, thermal, optical, and hygroscopic environments. Use of optical coherence tomography (OCT) as a potential diagnostic imaging modality in human skin was recognized in seminal studies by Schmitt et. al.1Recent results2demonstrate that the major structural components of human skin (i.e., epidermis and dermis) may be resolved using OCT. In the following, we discuss two potential dermatological applications of OCT, present images of ex-vivo human skin, and speculate on directions for future research.
An Imaging System for Low Coherence Tomography
Authors: Lankenau Eva , Koch Peter , Engelhardt Ralf
Published: February 2023

We investigate methods to realise optical low coherence tomography with field illumination and an imaging system. The coherence gated measurements are performed with a Michelson interferometer, imaging optics and a slow-scan CCD camera. The probe is illuminated by a parallel beam with a diameter of up to 1mm. A limitation of this method is set by multiple scattering within the tissue. To describe the influence of multiple scattered photons, light is focused on the sample and the backscattered light is superimposed by a parallel reference beam. We describe the limits for measuring 3-dimensional structures within scattering samples.
Intensity Modulated Breast Imaging: Technology and Clinical Pilot Study Results
Authors: Jess Helge , Erdl Helmut , Moesta K. Thomas , Fantini Sergio , Franceschini Maria Angela , Gratton Enrico , Kaschke Michael
Published: February 2023

We present an instrument for frequency-domain light mammography (LIMA) which is currently undergoing a clinical test. This instrument uses two laser diodes (690 and 825 nm) which are intensity modulated at a frequency of 110 MHz. The optical signal is detected in a transmission geometry with the breast slightly compressed between two glass plates. Edge effects are corrected by an algorithm of data analysis which enhances the contrast of the optical mammograms. We report the initial results obtained with the LIMA system in the detection of malignant tumors in 69 patients. Out of 37 malignant tumors, 27 tumors (73%) were successfully detected, which shows the feasibility' and the significant potential of the method. The analysis of the 10 cases (27%) in which the tumors were not detected by LIMA provides us with a valuable input for further improvement of the current system.
Electro-Optical Scanner Using Phased Array Optical Systems
Authors: Zhou Shuoming , Xie Chunhua , Zhao Shiyin , Liu Hanli , He Libo , Nioka Shoko , Chance Britton
Published: February 2023

The problem of obtaining the precise localization of a hidden absorber in a highly scattering medium of large dimension has confronted the scientific community for a number of years. Optical methods can also use contrast agents and can identify a line from the tissue surface, including the localized contrast agent and hence the tumor. Localization of absorbers/fluorochromes deep within a highly scattering large body of tissue such as the human breast can be effected most precisely by photon diffusive waves (Yodh, physical Review) that are not only amplitude modulated in the MHz region. If they consist of paired sources or detector, in-phase and anti-phase signal can be obtained to establish a null plane (Ref 1,2,3). Such a null plane is highly sensitive to perturbations by extremely small objects, of the order of the size of 70 microliters volume and containing as little as 20 picamole of an absorber. The null plane afforded by the in phase and out of phase cancellation diffusive wave is extremely narrow, and displacements of the array with respect to the hidden absorber of a fraction of a millimeter can be detected. Previous work has shown that the multiple source array consisting of portion of laser diode modulated at 200Mhz (50Mhz) RF signal 180 degree out of phase with the rest of the array gives a sharp phase transition and amplitude null plane. This plane provides a sensitive way for the detection of heterogeneity, and thereby may be used for the localization of small tumors within the human tissue. In order to enlarge the search field for phased array, the amplitude of the RF(200Mhz or 50 MHz) is modulated' by a second lower frequency signal(60 Hz),the phase transition plane moves back and forth in the certain region at the lower frequency. That is the principle of electronic scanning of the phased array. With this technology, we can make a real-time display of the line sight, which can goide the needle to the tumor in the surgeon's biopsy operation. In this paper, we will present the work for the localization of object in media using the phased array scanning.
Back-Projection Reconstructions of Cylindrical Inhomogeneities from Frequency Domain Optical Measurements in Turbid Media
Authors: Walker Scott A. , Fantini Sergio , Gratton Enrico
Published: February 2023

We propose a fast, simple method of reconstruction, similar to x-ray ct, where the physical parameters are calculated from frequency domain data and back-projected to form an image of the region of interest. Images are shown for centimeter size inhomogeneities with optical properties similar the those of human tissue. Data is collected single and multiple inhomogeneities from linear scans with a source-detector separation of 5 cm (source λ=793 nm, frequency=120 MHz). While, objects are located correctly with this technique, optical properties are recovered only qualitatively.
Diffusive Emission Tomography
Authors: Schotland John C. , Ishii Masaru
Published: February 2023

We consider the problem of emission tomography in a highly-scattering medium probed by diffusing waves. An analytic solution to the image reconstruction problem is presented.
Reconstruction of diffuse photon density wave interference for detection of small inhomogeneities in turbid media
Authors: Lindquist Charlotta , Pifferi Antonio , Andersson-Engels Stefan , Svanberg Sune
Published: February 2023

Photon-density wave interference was reconstructed from sequential time-resolved transmittance experiments. The two "interfering” sources were applied one at the time and the results were Fourier transformed, one of them phase shifted by n radians at the desired modulation frequency, and then added to each other. This gives us the possibility to study any modulation frequency we want without repeating the measurement. Apart from providing high spatial resolution, the technique of photon density wave interference gives a high detectability of regions with minor deviations in optical properties.
A Comparison of the Sensitivity of Continuous Wave and Frequency Domain Systems to Changes in the Absorption and Scattering Coefficients of Tissue
Authors: Farrell T.J. , Patterson M.S. , Essenpreis M. , Böcker D.
Published: February 2023

Analysis of the uncertainties in the optical properties obtained from reflectance data was used to compare the performance of the continuous wave and frequency domain approaches. The surface corresponding to the uncertainty as a function of the noise levels in steady state reflectance and phase difference reveals three distinct domains: a domain in which frequency domain data does not improve sensitivity, a domain in which continuous wave data does not improve sensitivity and a domain in which combining continuous wave and steady state data is an advantageous strategy. The noise levels which define these domains depend upon the optical properties of the tissue and the distances at which measurements are made. Presently, for typical optical properties and homogeneous tissues, optical systems which measure reflectance at short distances operate in the domain for which frequency domain information does not improve sensitivity and continuous wave systems will provide the best sensitivity to changes in optical properties.
Flow Properties of Heterogeneous Turbid Media Probed by Diffusing Temporal Correlation
Authors: Boas D. A. , Meglinsky I. V. , Zemany L. , Campbell L. E. , Chance B. , Yodh A. G.
Published: February 2023

Variations in the amplitude and phase of diffuse photon density waves
is known to yield important information about the structural
properties of turbid media, such as the scattering and absorption
coefficients. Information on the dynamical properties of turbid media
may be obtained from the temporal fluctuations of light fields
emanating from the media. In this contribution, we demonstrate that
variations in temporal correlation functions of the temporal intensity
fluctuations of different speckles of light can be used to derive
information about the spatially varying dynamical
properties of turbid media. We first present a diffusion for the
temporal correlation function for systems where the dynamics are
governed by Brownian motion and shear and random flow. We demonstrate
the validity of the correlation diffusion for heterogeneous systems by
comparing the theoretical results with experimental results for
systems governed by different dynamical processes, e.g. flow. As an
illustration of the usefulness of this correlation technique to
biomedical optics, we discuss the application of this technique to
diagnosing the thickness of burned tissue. The correlation diffusion
is an important, unique tool for analyzing the complex dynamical
signals that arise from heterogeneous biological systems.
Three-Dimensional Tumor Localization in Thick Tissue Using Measurements in a Plane
Authors: Matson Charles L. , Clark Natalie , McMackin Lenore , Fender Janet S.
Published: February 2023

Diffuse photon density waves are used to provide three-dimensional tumor localization in thick tissue using a single set of measurements in a plane. Lateral localization occurs in the detection plane, while a Fourier optics approach is used to backpropagate the wave throughout the tissue volume for depth localization. Computer simulation results are presented which validate the technique.
Measurements of effective group index of refraction and scattering mean free path of normal and malignant human breast tissues using ultrafast optical techniques
Authors: Liu Feng , Shan Y. X. , Savage H. , Heerdt A. S. , Schantz S. , Celmer E. , Alfano R. R.
Published: February 2023

Effective group index of refraction and scattering mean free path of human breast tissues at 625 nm were measured using femtosecond time-resolved cross correlation technique.
Determination of the Asymmetry Parameter and Scattering Coefficient of Turbid Media from Spatially Resolved Reflectance Measurements
Authors: Jones Matthew R. , Yamada Yukio
Published: February 2023

We present a technique for determining the asymmetry parameter and scattering coefficient of turbid media from spatially resolved reflectance measurements. This technique will contribute to the development of medical applications in which it is necessary to predict the distribution and propagation of light in tissue. Based on Monte Carlo simulations, we derived correlations which relate the reduced scattering coefficient and the asymmetry parameter to the relative reflectance curve. Initial estimates of the optical properties are obtained from these correlations. Final values are obtained by adjusting the optical parameters and repeating the Monte Carlo simulations until the simulated reflectance pattern matches the measured reflectance pattern. In preliminary experiments using dilute suspensions of polystyrene spheres, we determined the asymmetry parameter to within 10% and the reduced scattering coefficient to within 5%.
Electromagnetic Resonances in Low Density Collections of Dielectric Spheres
Authors: Stoytchev M. , Garcia N. , Genack A. Z.
Published: February 2023

The diffusion coefficient D and the transport mean free path ℓ of microwave radiation have been measured in random collections of 0.95 cm diameter alumina spheres at a volume filling fraction of 0.06. Both parameters show sharp resonances as the frequency is tuned. From the measured values of D and ℓ the transport velocity v
E
has been calculated. Values of v
E
as small as 1/5 of the speed of light in vacuum are observed.
Ultrasound-Modulated Optical Tomography
Authors: Wang Lihong , Zhao Xuemei , Jacques Steven L.
Published: February 2023

Continuous-wave ultrasonic modulation of scattered laser light has been used to image objects in tissue-simulating turbid media for the first time.1 We hypothesized that the ultrasound wave focused into the turbid media modulates the laser light passing through the ultrasonic focal zone. The modulated laser light collected by a photomultiplier tube reflects the local mechanical and optical properties in the focal zone. Buried objects in 5-cm thick tissue phantoms (absorption coefficient μa = 0.1 cm−1, reduced scattering coefficient μs′ = 10 cm−1) were located with millimeter resolution by scanning and detecting alterations of the ultrasound-modulated optical signal.
Acousto-optic imaging of absorbing structures with multiply-scattered light
Authors: Kempe M. , Larionov M. , Zaslavsky D. , Genack A.Z.
Published: February 2023

We have measured the dependence of the modulation of the light field transmitted through a scattering medium by a quasi-cw ultrasound beam upon sample thickness and parameters of the optical and acoustic excitation. A modulation signal is obtained using heterodyne detection for samples with anisotropy parameter g = 0.85 which are thicker than 100 scattering mean free paths. Tomographic imaging with diffuse light is demonstrated in a sample which is about 40 scattering mean free paths thick and contains an absorbing sphere. The results are in accord with a prediction that the modulation signal is proportional to the volume integral of the product of the optical intensity, the probability that a photon will arrive at the detector from this point and the acoustic intensity. Some factors that determine the signal-to-noise ratio for this imaging modality are discussed.
2-D Fluorescence Lifetime Imaging using a Time-Gated Image Intensifier
Authors: Dowling K. , Hyde S.C.W. , Dainty J.C. , French P.M.W. , Hares J.D.
Published: February 2023

We report a 2-D fluorescence lifetime imaging system with 185 ps (potentially sub-100 ps) temporal resolution. The impact of optical scattering is experimentally investigated.
Failure of radiative transport theory in homogeneous scattering media to predict the Point Spread Function (PSF) of transillumination images through some biologic tissues
Authors: Depeursinge Christian , Bevilacqua Frédéric , Marquet Pierre
Published: February 2023

Monte Carlo simulations or, to a lesser degree of accuracy, the resolution of the diffusion are generally considered as giving reasonable evaluations of the photon irradiance in tissues, globally described by the radiative transport theory. They are frequently used to calculate the Point Spread Function (PSF) describing the sharpness of transillumination images, resolved either in time or in frequency domain. The PSF is itself completely determined, for an homogenous slab of tissue and in the approximation of the diffusion equation, by the reduced scattering and absorption coefficients: µs' and µa respectively. For some tissue preparations, precise measurements of the PSF show, however, significant discrepancies between the predictions from µs′ and µa and the measured PSF. The propagation of light in biological tissues has been studied both theoretically by Monte Carlo simulations and experimentally in vitro on bovine and porcine liver, fat emulsions, human breast and brain tissues. Absorption and reduced scattering coefficients have been obtained and assessed by matching both the spatial and temporal profiles of a pulsed, collimated light beam to the experimental data. Measurements on fat emulsions and liver exhibit an excellent agreement between the predictions of the radiative transport theory for both spatial and temporal profiles. On the contrary, the spatial profile measured on adipose, breast and brain tissues are systematically too large to be predicted by the radiative transport theory in homogenous tissues. The tissue structure, in particular, the tissue micro and macroheterogeneities and possible site percolation in the model of light transport, not yet evidenced experimentally, could explain the unexpected broadening of the PSF in transillumination images through some tissues like adipose and brain .
Theoretical Analysis of Pencil Beams With Highly Forward Scattering
Authors: Larsen Edward W.
Published: February 2023

A normally-incident and infinitely narrow beam of radiation impinges on a homogeneous material. As this beam penetrates the system, the particles in the beam undergo scattering and the beam broadens. Explicit expressions for the amplitude and the root-mean-squared radius of the beam, as a function of depth, are derived from the linear transport The analogous expressions are derived for the approximate diffusion solution, and the two results are compared.
Wavelet Based Multigrid Reconstruction Algorithm for Optical Tomography
Authors: Zhu Wenwu , Wang Yao , Yao Yuqi , Barbour Randall L.
Published: February 2023

In this paper, we present a wavelet based multigrid approach to solve the perturbation encountered in optical tomography. The wavelet based multigrid representation has been applied to obtain regularized least squares (RLS) and total least squares (TLS) solutions. The unknown image, the data, as well as the weight matrix are all represented by wavelet expansions, thus yielding a multi-resolution representation of the perturbation Then, the transformed perturbation is solved by either the RLS or TLS method, using a multigrid scheme, by which an increasing portion of wavelet coefficients of the unknown image are solved in successive approximations. The experimental results show that the multigrid method can achieve similar reconstruction quality with a significantly reduced amount of time than the one-grid algorithm.
Image Reconstruction of Phantom with plural Absorbing Rods in Optical CT
Authors: Eda Hideo , Oda Ichiro , Ito Yasunobu , Wada Yukihisa
Published: February 2023

Reconstructed images of Cylindrical phantom with plural absorbing rods are presented. TEAM/FBP gives best spatial resolution. CW/Weight gives better in accuracy of absorption coefficient.
3D BackProjection Tomography for Medical Optical Imaging
Authors: Colak S.B. , Hooft G.W.’t , Papaioannou D.G. , van der Mark M.B.
Published: February 2023

A modified backprojection image reconstruction method has been applied to obtain three dimensional (3D) experimental tomographic images of objects in biological-tissue-like diffusive media.
Imaging Through Turbid Media with a Nonlinear-Optical Correlation Time Gate
Authors: Lantz E. , Devaux F. , Tolguenec G. Le , Maillotte H.
Published: February 2023

We demonstrate the use of a degenerate-four-wave-mixing time gate to allow imaging through turbid media, with potential application to tissue imaging. A near infra-red (NIR), long-pulse Cr+3:Li2SrA1F6 laser is used as the light source, for imaging through clear and turbid media.
Polarization Imaging and Characterization of Human Breast Tissue.
Authors: Demos S. G. , Savage H. , Heerdt Alexandra S. , Schantz S. , Alfano R. R.
Published: February 2023

Laser pulses propagating in human breast tissue depolarize to different degree depending on the type of tissue and wavelength over a time domain of ≈100 ps. This feature allows for optical imaging and characterization of the different components composing the tissue.
Modeling the Wavelength Dependence of the Early Arriving Fraction of a Short Optical Pulse Transmitted Through a Highly Scattering Medium
Authors: Penney C.M. , Pattanayak D.N. , Lotshaw W.T.
Published: February 2023

The wavelength dependence of light transport parameters of human tissue are estimated using Mie calculations of scattering from a simple model of a distribution of single sized spherical scatterers in an otherwise homogeneous background medium. The results are consistent with a dominant contribution to tissue scattering from small cellular or intercellular constituents such as mitochondria. The early arriving transmitted fraction of short optical pulses is calculated using both a diffusion approximation, and a Monte Carlo solution of the transport problem. Both predict enhancement of this transmission as the incident wavelength is changed from 700 nm to 1300 nm. However, the Monte Carlo solution predicts a much larger enhancement, showing strong disagreement with the diffusion result for early arriving photons at all tissue depths greater than a few millimeters.
Imaging through scattering media by parametric image amplification
Authors: Lantz E. , Devaux F. , Le Tolguenec G. , Maillotte H.
Published: February 2023

Parametric image amplification has been used to detect a chart through a milk cell 18 scattering mean free paths thick. The resolution on the object is about 20 μm.