Focal Shape Research Articles

How much is enough? The role of effort in market shaping

PurposeMarket shaping research predominantly focusses on the activities of the market shaper, rather than the equally important roles of other market actors. Market shapers may enhance resource density and value creation within markets, yet such influences cannot exhaustively explain how markets get shaped. Other market actors also must and do exert effort in the value co-creation processes; this study aims to explore the effects of reducing their efforts, as a mechanism to facilitate market shaping.Design/methodology/approachThis conceptual paper uses a theory adaptation approach to link value co-creation with market shaping and effort. It offers a conceptual framework and five propositions that outline the role of effort reduction in the value co-creation process to achieve market shaping.FindingsThe proposed conceptual framework indicates how enhanced resource density, resulting from the firm’s market shaping activities and reduced effort lead to enhanced value creation for market actors. Effort reduction can be achieved by reducing either the level of resource input required or the activities required to access, transform and combine resources to co-create value. Potential resource flows then may benefit the market shaper.Originality/valueThis research contributes to emergent market shaping literature by offering effort reduction as a viable tactic. Specifically, it broadens the scope of consideration of effort in value co-creation, and it advances understanding of resource density as a focal market shaping construct. The resultant framework offers a foundation for future market shaping research.

Focal-shape effects on the efficiency of the tunnel-ionization probe for extreme laser intensities

We examine the effect of laser focusing on the effectiveness of a recently discussed scheme [M. F. Ciappina et al., Phys. Rev. A 99, 043405 (2019) and M. F. Ciappina and S. V. Popruzhenko, Laser Phys. Lett. 17, 025301 (2020)] for in situ determination of ultrahigh intensities of electromagnetic radiation delivered by multi-petawatt laser facilities. Using two model intensity distributions in the focus of a laser beam, we show how the resulting yields of highly charged ions generated in the process of multiple sequential tunneling of electrons from atoms depend on the shapes of these distributions. Our findings lead to the conclusion that an accurate extraction of the peak laser intensity can be made either in the near-threshold regime, when the production of the highest charge state happens only in a small part of the laser focus close to the point where the intensity is maximal or through the determination of the points where the ion yields of close charges become equal. We show that for realistic parameters of the gas target, the number of ions generated in the central part of the focus in the threshold regime should be sufficient for a reliable measurement with highly sensitive time-of-flight detectors. Although the positions of the intersection points generally depend on the focal shape, they can be used to localize the peak intensity value in certain intervals. Finally, the slope of the intensity-dependent ion yields is shown to be robust with respect to both the focal spot size and the spatial distribution of the laser intensity in the focus. When these slopes can be measured, they will provide the most accurate determination of the peak intensity value within the considered tunnel ionization scheme. In addition to this analysis, we discuss the method in comparison with other recently proposed approaches for direct measurement of extreme laser intensities.

A Method to Generate Vector Beams with Adjustable Amplitude in the Focal Plane

We design and investigate an original optical component made of a c-cut uniaxial crystal and an optical system to generate cylindrical vector beams with an adjustable polarization state. The original optical component has a specific, nearly conical shape which allows it to operate like a broadband wave retarder with the fast axis oriented radially with respect to the optical axis. We show via numerical simulations, using the Debye–Wolf diffraction integral, that the focal spot changes depending on the polarization state, thus enabling the control of the focal shape. Non-symmetrical shapes can be created although the optical system and incoming beam are circularly symmetric. We explained, using Jones matrix formalism, that this phenomenon is connected with the Gouy phase difference acquired by certain modes composing the beam due to propagation to the focal plane. We present our conclusions in the context of two potential applications, namely, stimulated emission depletion (STED) microscopy and laser micromachining. The optical system can potentially be used for STED microscopy for better control of the point-spread function of the microscope and to decrease the unwanted light emitted from the surroundings of the focal point. We give an analytical expression for the shape of the original component using the aspherical lens formula for the two versions of the component: one for each potential application.

Tailored focal beam shaping and its application in laser material processing

Besides the optimization of the laser and processing parameters, the adaptation of the focal intensity distribution offers great potential for a well-defined control of laser processing and for improving the processing results. In this paper, different tailored intensity distributions were discussed with respect to their suitability for femtosecond laser material processing on the micro- and nanoscale such as cutting, marking, and the generation of laser-induced periodic surface structures. It was shown by means of laser processing of stainless steel that the numerical simulations for the beam shaping unit are in good agreement with the experimental results. Also, the suitability of the beam shaping device to work with a scanner and an F-theta lens as commonly used for material processing was demonstrated. In this context, the improvement of the machining results was shown experimentally, and a significant reduction of the machining time was achieved.

MORPHOLOGICAL PECULIARITIES OF RAT BONE MARROW UNDER THE INFLUENCE OF NITRATE SALTS IN INCREASED CONCENTRATIONS

The study of the qualitative composition of water and food products revealed the increased concentration of nitrates in their composition. Nitric acid salts in toxic doses can lead to disorders of the endocrine system, blood circulation, central nervous system, etc. Bone marrow is one of the most sensitive organs, which is responsible for the formation of cellular elements of blood. The object of our research was to study the morphological peculiarities of the bone marrow of rats under the influence of nitrate salts on the body and to determine the regularities of subacute and chronic hemotoxic effect of xenobiotics on the process of granulocyto-, erythrocyto- and thrombocytopoiesis. The study was conducted on 48 mature male rats. Nitrate Na (NaNO3) was used as xenobiotic. The animals were removed from the experiment on 10th, 30th and 90th day. The qualitative and quantitative composition of the parenchymatous and stromal component of the bone marrow was studied on the samples, stained with hematoxylin and eosin. During the experiment, the most expressed changes were observed in erythron: reduced number of nuclear cells in erythroid islands, signs of their diserythropoiesis – focal vacuolization, abnormal shape and size of the nuclei, their fragmentation, pathological inclusions in cytoplasm. Changes in granulocytopoiesis were expressed by the disturbance of their stratification – precursors with different degree of maturity were present in all parts of the medullary canal. Changes in megakaryocytes were expressed by their focal accumulation in the form of clusters and partial dislocation, regarding the sinusoids. The observations on animals revealed the term-dependent nature of changes in the bone marrow. On the 90th day, a progression of qualitative and quantitative changes in hematopoietic tissue was determined. The hemotoxic effect was expressed by disorders in the maturation of all its precursors – the ratio of parenchyma-stroma was still reduced, dysplastic changes in erythron increased, focal dystrophic changes in the stromal component of the bone marrow were observed.

High-Intensity Focused Ultrasound Therapy in the Uterine Fibroid: A Clinical Case Study of Poor Heating Efficacy.

A clinical case study of high-intensity focused ultrasound (HIFU) treatment in the uterine fibroid was conducted. During the therapy, poor heating efficacy was observed which could be attributed to several factors such as the local perfusion rate, patient-specific anatomy or changes in acoustic parameters of the ultrasound field. In order to determine the cause of the diminished heating, perfusion analyses and ultrasound simulations were conducted using the magnetic resonance imaging (MRI) data from the treatment. The perfusion analysis showed high local perfusion rate in the myoma (301.0 ± 25.6 mL/100 g/min) compared to the surrounding myometrium (233.8 ± 16.2 mL/100 g/min). The ultrasound simulations did not show large differences in the focal point shape or the acoustic pressure (2.07 ± 0.06 MPa) when tilting the transducer. However, a small shift (-2.2 ± 1.3 mm) in the axial location of the focal point was observed. The main causes for the diminished heating were likely the high local perfusion and ultrasound attenuation due to the deep location of the myoma.

Methodology to design optical systems with curved sensors.

Curved sensors are a suitable technological solution to enhance the vast majority of optical systems. In this work, we show the entire process to create curved sensor-based optical systems and the possibilities they offer. This paper defines the boundaries of the reachable curvatures for a full range of monolithic sensors. We discuss how the curved focal plane shape is related to the imaged scenes and optical parameters. Two camera prototypes are designed, realized, and tested, demonstrating a new compact optical architecture for a 40deg compact objective as well as a wide-field fisheye zoom objective using a convex sensor to image a 180deg field of view.

PA-32 焦点面形状を制御した結石破砕音場の破砕力評価(P.ポスターセッションA-概要講演・展示)

PA-32 焦点面形状を制御した結石破砕音場の破砕力評価(P.ポスターセッションA-概要講演・展示)

Some exact solutions for light beams

We give an infinite class of exact analytical solutions for monochromatic light beams with strong focusing. As the solutions do not contain integrals, they are easy to explore compared with diffraction-theory results for strongly focused light. All monochromatic beams can be decomposed into two standing waves, each proportional to a Hilbert transform of the other. This means a beam can be built from any standing wave and our class is derived using this procedure. We give a visual overview of some of the beams, which reveals many interesting energy and field structures, including vortices in the energy flow, angular momentum in the propagation direction, and knotted field lines. We also show how the method can be used to design beams with an arbitrary focal shape.

Self-adaptive ultrasonic beam amplifiers: application to transcostal shock wave therapy

Ultrasound shock wave therapy is increasingly used for non-invasive surgery. It requires the focusing of very high pressure amplitude in precisely controlled focal spots. In transcostal therapy of the heart or the liver, the high impedance mismatch between the bones and surrounding tissues gives rise to strong aberrations and attenuation of the therapeutic wavefront, with potential risks of injury at the tissue-bone interface. An adaptive propagation of the ultrasonic beam through the intercostal spaces would be required. Several solutions have been developed so far, but they require a prior knowledge of the patient’s anatomy or an invasive calibration process, not applicable in clinic. Here, we develop a non-invasive adaptive focusing method for ultrasound therapy through the ribcage using a time reversal cavity (TRC) acting as an ultrasonic beam amplifier. This method is based on ribcage imaging through the TRC and a projection orthogonally to the strongest identified reflectors. The focal pressure of our device was improved by up to 30% using such self-adaptive processing, without degrading the focal spots size and shape. This improvement allowed lesion formation in an Ultracal® phantom through a ribcage without invasive calibration of the device. This adaptive method could be particularly interesting to improve the efficiency and the safety of pulsed cavitational therapy of the heart or the liver.

Effects of breast structure on high-intensity focused ultrasound focal error

BackgroundThe development of imaging technologies and breast cancer screening allowed early detection of breast cancers. High-intensity focused ultrasound (HIFU) is a non-invasive cancer treatment, but the success of HIFU ablation was depending on the system type, imaging technique, ablation protocol, and patient selection. Therefore, we aimed to determine the relationship between breast tissue structure and focal error during breast cancer HIFU treatment.MethodsNumerical simulations of the breast cancer HIFU ablation were performed using digital breast phantoms constructed using the magnetic resonance imaging data obtained from 12 patients.ResultsThe focal shapes were distorted despite breast tissue representing soft tissue. Focal errors are caused by the complex distribution of fibroglandular tissue, and they depend on the target position and the arrangement of the transducer. We demonstrated that the focusing ratio increases with the decrease in the local acoustic inhomogeneity, implying that it may be used as an indicator to reduce the HIFU focal error depending on the breast structure.ConclusionsThe obtained results demonstrated that the focal error observed during the breast cancer HIFU treatment is highly dependent on the structure of fibroglandular tissue. The optimal arrangement of the transducer to the target can be obtained by minimizing the local acoustic inhomogeneity before the breast cancer HIFU treatment.

How Goal Specificity Shapes Motivation: A Reference Points Perspective

AbstractConsumers often pursue goals that lack specific end states, such as goals to lose as much weight as possible or to pay off as much debt as possible. Yet despite considerable interest in the consequences of setting nonspecific (vs. specific) goals, how goal specificity affects motivation throughout goal pursuit is less well understood. The current research explores the role of reference points in shaping goal specificity’s effects. We propose that goal specificity alters what reference point consumers spontaneously adopt during goal pursuit: for specific goals, the end state tends to be more salient, but for nonspecific goals, the initial state should be more salient. Five studies investigate how this difference in focal reference points shapes (1) the relationship between goal progress and motivation, (2) when (i.e., at what level of goal progress) goal specificity produces the greatest difference in motivation, and (3) the underlying process driving these effects. Our findings advance understanding of the relationship between goal specificity, goal progress, and motivation, and in doing so, underscore the critical role that reference points play in goal-directed behavior. In addition, the findings offer practical insight into how best to set important financial, health, and other consumer goals to enhance motivation.

Focus shaping of cylindrically polarized Bessel–Gaussian beam modulated by Bessel gratings by a high numerical aperture objective

The focus-shaping technique of the cylindrically polarized Bessel–Gaussian-like beam, referred to the cylindrically polarized Bessel–Gaussian beam modulated by Bessel gratings, propagating through a high numerical-aperture lens is investigated theoretically and numerically in this paper, using the vector diffraction theory method. Results show that the intensity distribution in the focal region can be influenced considerably by: the beam topological charges (m, n), the beam parameter β and the polarization angle ϕ0. The intensity distribution in focal region can be tailored considerably by appropriately adjusting the polarization angle. Peak-centered, donut and flattop focal shapes with extended focal depth which are potentially useful in optical tweezers, material processing and laser printing can be obtained using this technique.

Vimentin Levels and Serine 71 Phosphorylation in the Control of Cell-Matrix Adhesions, Migration Speed, and Shape of Transformed Human Fibroblasts.

Metastasizing tumor cells show increased expression of the intermediate filament (IF) protein vimentin, which has been used to diagnose invasive tumors for decades. Recent observations indicate that vimentin is not only a passive marker for carcinoma, but may also induce tumor cell invasion. To clarify how vimentin IFs control cell adhesions and migration, we analyzed the nanoscale (30–50 nm) spatial organization of vimentin IFs and cell-matrix adhesions in metastatic fibroblast cells, using three-color stimulated emission depletion (STED) microscopy. We also studied whether wild-type and phospho-deficient or -mimicking mutants of vimentin changed the size and lifetime of focal adhesions (FAs), cell shape, and cell migration, using live-cell total internal reflection imaging and confocal microscopy. We observed that vimentin exists in fragments of different lengths. Short fragments were mostly the size of a unit-length filament and were mainly localized close to small cell-matrix adhesions. Long vimentin filaments were found in the proximity of large FAs. Vimentin expression in these cells caused a reduction in FAs size and an elongated cell shape, but did not affect FA lifetime, or the speed or directionality of cell migration. Expression of a phospho-mimicking mutant (S71D) of vimentin increased the speed of cell migration. Taken together, our results suggest that in highly migratory, transformed mesenchymal cells, vimentin levels control the cell shape and FA size, but not cell migration, which instead is linked to the phosphorylation status of S71 vimentin. These observations are consistent with the possibility that not only levels, but also the assembly status of vimentin control cell migration.

3-D Shaping of a Focused Aperture in the Near Field

The manipulation of the near-field (NF) is a challenging topic in electromagnetics, carrying essential importance for several applications. In this paper, we develop an algorithm capable of shaping the NF in 3-D domains according to given specifications. The algorithm is based on a set theoretic approach and a front-and-back iterative propagation scheme. The latter is realized using fast Fourier transforms (FFT), reducing the required computational time. The algorithm is applied on a focal shaping scenario. In this case, a full control of the depth of focus, spot diameter, and sidelobe level of the generated radiation is achieved. In particular, the proposed procedure is successfully adopted to control the normal component of a radiating aperture over a range of $12 {\lambda }$ at 30 GHz. The derived aperture field distribution is then synthesized by a radial line slot antenna (RLSA) by means of an in-house method of moments (MoM) code. NF measurements have validated the proposed approach and prototype.

Enhanced performance of refractive laser beam shapers through additional phase control at focus

Laser beam shaping at focus or focal beam shaping is essential for many applications. The most common approach makes use of the Fourier transforming properties of lenses to generate at their focal planes the desired irradiance patterns, e.g., the flattop. There are two inherent limitations for this approach. First, the shaping quality depends strongly on the dimensionless parameter β . In the case of a long focal length or small beam sizes giving a small β value, additional beam expanders are needed to achieve a satisfying irradiance pattern at the focus. Second, without considering the phase, the irradiance patterns beyond the focal plane are not controlled. We propose a different approach with two plano-aspheric lenses that allow control of both irradiance and phase at focus. The design method comprises an extended ray mapping procedure combined with backward wave propagation from focus. With this design approach, the shaping quality is guaranteed without the possible need for extra beam expanders, offering the potential for a more compact system with fewer elements. Through the additional phase control, the depth of focus is enlarged to a large extent and the designed system becomes more tolerant.

Tight focusing properties of cylindrically polarized annular multi-Gaussian beam

Focusing properties of cylindrically polarized annular multi gaussian beam with high numerical aperture lens system is investigated theoretically by vector diffraction theory. Results show that intensity distribution in focal region can be tailored considerably by appropriately adjusting the polarization angle. Peak-centered, donut and flattop focal shapes with extended focal depth, potentially useful in optical tweezers, material processing and laser printing can be obtained using this technique.

Morphological and functional changes in rat incisor triggered by chronic exposure to fluoride

Ultrafast laser photoinscription and laser-based refractive index engineering develop towards a unique way for three-dimensional optical design inside bulk materials for the conception of embedded photonic applications. The specific optical functions for the light guiding elements, notably their single mode characteristics and the accessible spectral domains, depend on the achieved refractive index contrast in the material transparency window and on the characteristic dimensions of the optical modification. We give here an overview of several laser processing options, developed to increase the effective index area and contrast using pulse engineering methods in space and time, and optical design involving focal shaping, tubular concepts, evanescently coupled waveguide arrays, or structured waveguides.

Evaluation of the effect of jaw shape/size options in a new brand of digital panoramic machine on the accuracy of linear and angular measurements

Introduction: Although placement of structures within the focal trough is important, image sharpness is affected by other factors such as the shape and size of the jaw in panoramic machines. The aim of this study was to evaluate the effect of jaw shape/size options in a digital panoramic machine on the accuracy of linear and angular measurements. Materials and Methods: In this in vitro study, one dry human skull was chosen, and hypothetical tooth positions were determined. Horizontal, vertical, and angular dimensions were indicated by gutta-percha in tooth positions and assessed by two observers. After determining jaw shape and size, standard panoramic radiographs were obtained in 6 positions by changing the focal trough shape and with two other shapes and one larger size of the jaw. Linear and angular measurements were made by two separate observers individually on each radiograph. Statistical analysis was performed by SPSS 20. Intraclass correlation coefficient (ICC) and paired t -test were used for data analysis. Results: According to ICC values, inter-observer correlations for radiographic measurements and for physical measurements were 0.994 and 0.995, respectively ( P P P > 0.05). Conclusions: The results of the present study indicated that vertical and angular measurements were clinically reliable with all the options. However, jaw size and shape options which changed the focal trough did not improve the accuracy of horizontal measurements.

Influence of pupil on the laser beam shaping system by pure phase modulation

In this paper, we propose a quantitative approach to analyze the influence of pupil truncation on the phase-only modulation laser beam shaping system, based on the near-field phase and the far-field metric functions. First, the relationship between near-field phase and pupil radius is studied by Lagrange multiplier method. Result indicates that both the peak-to-valley and the root-mean-square of the near-field phase increase approximately linearly with the pupil radius. Second, the influence of pupil radius on a beam shaping system is investigated. To quantify the performance of the beam shaping system, the correlation coefficient (C) and the mean square difference (MSD) are introduced as the metric functions. Then, by comparing the metric functions at different pupil radius, it is shown that the pupil radius influences the performance of focal beam shaping distinctly at the lower pupil radius, whereas the influence trails off, and both the C and the MSD get close to the theoretical limit as the pupil radius continuously increases. Third, the mathematical models of the C and the MSD are proposed to reveal the relationship among the metric functions, pupil radius and target intensity's size, as it is difficult to obtain the explicit expressions on the basis of metric functions' definition. And the three coefficients in each model are ascertained by surface fitting method based on the sampling data. In addition, SSE (sum of square due to error), RMSE (root mean square error) and R-square (coefficient of determination) are adopted to determine the fitting precision. For both the metric functions, the precision of SSE and RMSE can reach 10-2 and the R-square is shown to be more than 97%. The SSE, RMSE and R-square verify the proposed mathematical models. Finally, according to the models, we analyze when the influence of pupil truncation becomes negligible for the rectangle or circle target intensity. In practice, the size of target intensity is determined first. Sequentially, by combining the mathematical models and their first-order partial differentials, the changing regularity of metric functions with respect to pupil radius is studied. Meanwhile, the regularity helps us to find the beginning points for rectangle target and circle target intensities respectively. For the rectangle target intensity, when the pupil radius is 2.5 times that of the Gaussian waist radius, the metric functions become stable. The C with a value of 0.997 and the MSD with a value of 410-4 are both close to the theoretical limit. In the meantime, the influence of pupil truncation tends to be minimal as expected. For circle target intensity, when the pupil radius is 3 times that of the Gaussian waist radius, the first-order partial differentials of the C and the MSD decrease to about 10-3. This means that the metric functions begin to converge and that the influence of pupil truncation tends to be minimal at this point. Consequently, it is effective and meaningful to determine the best pupil radius using the proposed models in the article when designing a beam shaping system. Moreover, the models can also be used to evaluate the performance of a laser beam shaping system.