Multiple Focusing Research Articles

Neurostimulation in neurogenic patients.

To provide an overview of available electrical stimulation devices in neurogenic patients with lower urinary tract disease. It is advocated to do more studies in neurogenic patients as results seem promising and useful but most studies did not include neurogenic patients or neurogenic patients were not analyzed or reported separately. Most studies included a small heterogenous neurogenic group with multiple pathophysiologic origin focusing on effect of a treatment instead of results of a treatment in a specific neurogenic group. Neuromodulation or stimulation has the advantage that it acts on different organs, like bladder and bowel, so can treat neurogenic patients, who mostly suffer from multiple organ failure. Brindley procedure, sacral neuromodulation (SNM) and posterior tibial nerve stimulation (PTNS) are available for a while already. The Brindley procedure (including sacral anterior root stimulation in combination with a rhizotomy of posterior sacral roots) is developed for selected spinal cord injury patient with a complete spinal injury, and has shown results for many years in neurogenic patients. An alternative to the rhizotomy is not established yet. SNM and PTNS are other modalities that are used in nonneurogenic patients, but are not yet indicated and much studied in neurogenic patients.

Viscoelastic second normal stress difference dominated multiple-stream particle focusing in microfluidic channels.

Particle focusing in viscoelastic fluid flow is a promising approach for inducing particle separations in microfluidic devices. The results from theoretical studies indicated that multiple stream particle focusing can be realized with a large magnitude of the elastic second normal stress difference (N2). For dilute polymer solutions, theoretical and experimental studies show that the magnitude of N2 is never large, no matter how large the polymer molecular weight nor how high the shear rate. However, for concentrated entangled polymer solutions, the magnitude of N2 becomes large at high shear rates. Therefore, in order to test the hypothesis that N2 can be used to induce multiple particle stream focusing behavior, we perform the systematic study of the effects of increasing carrier fluid polymer concentrations in a microchannel containing fluorescent particles. In a dilute polymer solution, multiple particle stream focusing is not observed, even at high shear rates and large dimensionless Weissenberg number values (Wi ≈ 30) at which the elastic first normal stress difference (N1) and the viscosity shear-thinning should be very large, while in a concentrated entangled polymer solution, we observe that particle streams focused upon the channel centerline bifurcate to form two symmetric off-channel particle streams at higher shear rates. This particle focusing behavior is different from previous multiple-stream focusing phenomena, and that we attribute to the influence of the second normal stress difference N2. This N2 induced multiple stream focusing phenomenon provides a different approach for manipulating the particle trajectory and separation in a microchannel.

Fast 3D movement of a laser focusing spot behind scattering media by utilizing optical memory effect and optical conjugate planes

Controlling light propagation intentionally through turbid media such as ground glass or biological tissue has been demonstrated for many useful applications. Due to random scattering effect, one of the important goals is to draw a desired shape behind turbid media with a swift and precise method. Feedback wavefront shaping method which is known as a very effective approach to focus the light, is restricted by slow optimization process for obtaining multiple spots. Here we propose a technique to implement feedback wavefront shaping with optical memory effect and optical 4f system to speedy move focus spot and form shapes in 3D space behind scattering media. Starting with only one optimization process to achieve a focusing spot, the advantages of the optical configuration and full digital control allow us to move the focus spot with high quality at the speed of SLM frame rate. Multiple focusing spots can be achieved simultaneously by combining multiple phase patterns on a single SLM. By inheriting the phase patterns in the initial focusing process, we can enhance the intensity of the focusing spot at the edge of memory effect in with 50% reduction in optimization time. With a new focusing spot, we have two partially overlapped memory effect regions, expanding our 3D scanning range. With fast wavefront shaping devices, our proposed technique could potentially find appealing applications with biological tissues.

Councils’ environment management system: an isomorphism inquiry

Purpose The purpose of this paper is to understand how external and internal drivers influence the implementation of the environment management system by selected local councils in Malaysia from the institutional theory and national culture perspectives. Design/methodology/approach This research used a multiple case study approach focusing on three selected Malaysian local councils. The data collection method included semi-structured interviews with officers directly involved in the environment management system implementation. Findings Organizations are more influenced by external rather than internal drivers in implementing the environment management system, and dominated by the normative pressure. This study offers insights into the effectiveness of the identified drivers in the environment management system implementation process, by relating to the type of conformance, either by “compliance” or “convergence.” Research limitations/implications This study demonstrates the effect of national culture on the isomorphic influences of the internal and external motivations by local councils to implement the environment management system, namely, large power distance, collectivism, short-term normative orientation, masculinity and uncertainty avoidance. Practical implications The outcomes can be useful to managers of local councils with responsibilities for environmental decision making. Originality/value Institutional theory and national culture values are used successfully to explain the implementation of the environment management system in the three selected Malaysian councils in this study, in line with the public sector reform agenda undertaken by the Malaysian Government.

As competências do guia de turismo: um estudo sobre os cursos de formação técnica no Brasil

No mundo contemporâneo a formação do profissional Guia de Turismo (GT) precisa ter em conta as mudanças e as adaptações exigidas pelos novos cenários empresariais e educacionais. O objetivo deste artigo foi mapear as competências comtempladas no perfil do egresso de cursos técnicos de GT no Brasil, tendo como pressuposto central do estudo que as competências do GT precisam ser focalizadas em valores para um saber-fazer e um saber-ser. A pesquisa de caráter documental focou na análise da legislação em Educação e em Turismo que rege a oferta dos cursos técnicos de GT no Brasil e nas competências declaradas pelas IEs a partir de seus planos de curso. Fez-se a opção pelo Estudo de Casos Múltiplos com foco em dez Instituições de Ensino que ofertam cursos Técnicos de GT no Brasil, bem como o estudo da legislação, normas e regras pertinentes. Os dados coletados foram conduzidos para uma Análise Textual Discursiva – ATD que permitiu identificar que na grande maioria das IE as competências organizacionais. Quanto às competências do “saber-ser”, ou seja, aquelas voltadas aos aspectos cognitivos, pouco são desenvolvidas. Destacou-se a liderança, a mediação e a interpretação, como expertise nas competências do GT.

Sustaining an intervention for physical health promotion in community mental health services: A multisite case study.

There is a growing body of literature on sustainability, but its definition and the factors that affect it are not well understood. This paper focuses on the sustainment of health promotion interventions in community mental health organisations, where the institutional context has been found to play an important role. Normalisation Process Theory (NPT) was used to characterise the extent of sustainment of health promotion interventions and to identify important factors that influence it. The study builds on a previously reported qualitative multiple case design focusing on four Danish community mental health organisations. We aimed to include cases (provider organisations) with varied political-administrative contexts that were expected to impact sustainment. Data included 27 semistructured interviews with managers and frontline staff. The analysis adopted a thematic approach combining within-case and cross-case analysis. One important factor contributing to sustainment was the high degree of coherence generated during and after implementation. Perceptions of meaningfulness and formal tools for external accountability such as municipal activity plans also stimulated the cognitive participation of management and staff in sustaining the intervention. On the practical level of collective action, working with health promotion in a continuous way was particularly supported by two formal tools: internal health policies and municipal activity plans. Sustainment was further aided by reflexive monitoring based on ongoing informal assessments, supplemented by information required for status reports to the municipality on individual users and information from the annual individual user health checks. Future studies should adapt NPT to a broader range of cases to assess more thoroughly its contribution to the literature on sustainment. Future interventions need to pay closer attention to securing continuous and active local management support as well as to political-administrative contexts as potential external drivers of sustainment.

A microfluidic binary logic device using inertia-elastic particle focusing

While a few attempts have been made on microfluidic logic devices, e.g., digital microfluidics and a fluid transistor, complete integration of digitalization into microfluidics is still a challenge. In this study, we investigate a microfluidic logic device that is built based on the particle dynamics in viscoelastic fluid. A logic gate system employing a Boolean function is implemented by utilizing multiple line particle focusing behavior in the microfluidic channel. The device is designed and fabricated to hydrodynamically control the logic operations of XOR, OR, AND, Buffer, and NOT under the fixed flow condition (e.g., flow rate, particle size, and fluid elasticity∼1.483). In addition, numerical simulation is carried out to understand the fundamental physics of the particle and fluid behavior in viscoelastic flow. Clear multiple particle focusing lines with high separation resolution (Rij∼6.19) were observed and the particle extraction at the outlets were analyzed by image-processing. This study is expected to open a new route to the incorporation of microfluidics with electronics by demonstrating logic gates based on microfluidics.

Multiple time-reversal focusing with a virtual source array

Time reversal (TR) is the process of generating a spatio-temporal focus at a probe source (PS) location by backpropagating a time-reversed version of a received signal. While TR focusing requires the PS for a coherent acoustic focus at its origin, the requirement of the PS has been partially relaxed by the concept of a virtual source array (VSA) [J. Acoust. Soc. Am. 125, 3828–3834 (2009)]. A VSA can serve as a remote platform or lens and redirect a focused field to a selected location beyond the VSA for which the field is assumed as a homogeneous medium with constant sound speed. The objective of this study is to extend VSA-based single TR focusing to simultaneous multiple focusing. This is achieved using the optimization theory by employing the multiple constraints method derived from a constraint matrix, which consists of appropriately synchronized transfer functions. It is found that simultaneous multiple focusing can be achieved with distortionless response at selected multiple locations, and its performance degrades in the presence of sound speed mismatch. Possible applications for the VSA-based TR focusing are discussed, and numerical simulation results are presentedTime reversal (TR) is the process of generating a spatio-temporal focus at a probe source (PS) location by backpropagating a time-reversed version of a received signal. While TR focusing requires the PS for a coherent acoustic focus at its origin, the requirement of the PS has been partially relaxed by the concept of a virtual source array (VSA) [J. Acoust. Soc. Am. 125, 3828–3834 (2009)]. A VSA can serve as a remote platform or lens and redirect a focused field to a selected location beyond the VSA for which the field is assumed as a homogeneous medium with constant sound speed. The objective of this study is to extend VSA-based single TR focusing to simultaneous multiple focusing. This is achieved using the optimization theory by employing the multiple constraints method derived from a constraint matrix, which consists of appropriately synchronized transfer functions. It is found that simultaneous multiple focusing can be achieved with distortionless response at selected multiple locations, and its perf...

Multiple Vehicle Detection and Segmentation in Malaysia Traffic Flow

Vision based system are widely used in the field of Intelligent Transportation System (ITS) to extract a large amount of information to analyze traffic scenes. By rapid number of vehicles on the road as well as significant increase on cameras dictated the need for traffic surveillance systems. This system can take over the burden some task was performed by human operator in traffic monitoring centre. The main technique proposed by this paper is concentrated on developing a multiple vehicle detection and segmentation focusing on monitoring through Closed Circuit Television (CCTV) video. The system is able to automatically segment vehicle extracted from heavy traffic scene by optical flow estimation alongside with blob analysis technique in order to detect the moving vehicle. Prior to segmentation, blob analysis technique will compute the area of interest region corresponding to moving vehicle which will be used to create bounding box on that particular vehicle. Experimental validation on the proposed system was performed and the algorithm is demonstrated on various set of traffic scene.

Transcranial focused ultrasound with multielement arrays: Decreasing the number of transducers without compromising the focusing quality

Transcranial ultrasonic brain therapy at frequencies higher than 500 kHz requires adaptive focusing to compensate for the aberrations induced by the skull bone. This can be achieved by using multi-element arrays driven by a dedicated electronics. A growing number of elements was used to improve the focusing: 64 elements in 2000 [1], 300 in 2003 [2], 1024 in 2013 [3], and more to come. We will present some of the salient results obtained pre-clinically and clinically with such multi-element transcranial devices. Nevertheless, we will show that comparable transcranial focusing can be achieved with a novel approach in rupture with the current trend. It consists in a single-element transducer covered with a 3D silicone acoustic lens of variable and controlled thickness. Similar lenses have been introduced in the past to perform multiple focusing patterns in homogenous media [4] but recent 3d printing capabilities make 3D lenses a feasible option for transcranial adaptive focusing. We will show that the use of a lenses increases the acoustic intensity by 97 ± 56% on average, on three human skulls. [1] G. Clement et al., “A hemisphere array for non-invasive ultrasound brain therapy and surgery,” Phys. Med. Biol. 2000. [2] M. Pernot et al., “High power transcranial beam steering for ultrasonic brain therapy,” Phys. Med. Biol. 2003. [3] N. Lipsman et al., “MR-guided focused ultrasound thalamotomy for essential tremor: a proof-of-concept study,” The Lancet Neurology 2013. [4] T. Fjield et al., “Low-profile lenses for ultrasound surgery,” Phys. Med. Biol. 1999.

Married women, law and wealth in 14th-century Genoa

My aim here is to assess the relationship between the marital status of women and their ability to accrue wealth and dispose of it by drawing on multiple sources (especially statutes and notarial sources) and focusing specifically on non-dotal assets in 14th-century Genoa. During this period new norms were introduced in Genoa that echoed those which were being implemented in other north-central Italian cities. The late 13th-/early 14th-century Genoese statutes and the successive redaction of 1375 contain restrictive measures in regard to married women and wealth, but to what extent did practice fall squarely within these prescribed rules? Evidence in notarial sources suggests that while women continued to enjoy some leeway (especially when expressing their last wishes), law and practice largely coincided. This is especially evident in the tendency of married women to give full mandate to husbands to manage their personal property and in the conceptual assimilation of non-dotal assets to the dowry.

Virtual Source Array-Based Multiple Time-Reversal Focusing

Time reversal (TR) is the process of generating a spatio-temporal focus at a probe source (PS) location by transmitting a time-reversed version of a received signal. While TR focusing requires the PS for a coherent acoustic focus at its origin, the requirement of the PS has been partially relaxed by the introduction of the concept of a virtual source array (VSA) (J. Acoust. Soc. Am. 2009, 125, 3828–3834). A VSA can serve as a remote platform or lens and redirect a focused field to a selected location beyond the VSA for which the field is assumed as a homogeneous medium with constant sound speed. The objective of this study is to extend VSA-based single TR focusing to simultaneous multiple focusing. This is achieved using the optimization theory by employing the multiple constraints method derived from a constraint matrix, which consists of appropriately synchronized transfer functions. Through numerical simulations, it is found that simultaneous multiple focusing can be achieved with distortionless response at selected multiple locations, and its performance degrades in the presence of sound speed mismatch. For achieving robust multiple focusing in the mismatch environment, singular value decomposition is applied to obtain the weight vector (i.e., backpropagation vector) that best approximates the column vectors of the constraint matrix. Numerical simulation results show that VSA-based multiple TR focusing using SVD is not a method to simultaneously focus on multiple locations, but a method of constructing a field which robustly passes through multiple locations in sound speed mismatch environment.

Particle focusing by 3D inertial microfluidics

Three-dimensional (3D) particle focusing in microfluidics is a fundamental capability with a wide range of applications, such as on-chip flow cytometry, where high-throughput analysis at the single-cell level is performed. Currently, 3D focusing is achieved mainly in devices with complex layouts, additional sheath fluids, and complex pumping systems. In this work, we present a compact microfluidic device capable of 3D particle focusing at high flow rates and with a small footprint, without the requirement of external fields or lateral sheath flows, but using only a single-inlet, single-outlet microfluidic sequence of straight channels and tightly curving vertical loops. This device exploits inertial fluidic effects that occur in a laminar regime at sufficiently high flow rates, manipulating the particle positions by the combination of inertial lift forces and Dean drag forces. The device is fabricated by femtosecond laser irradiation followed by chemical etching, which is a simple two-step process enabling the creation of 3D microfluidic networks in fused silica glass substrates. The use of tightly curving three-dimensional microfluidic loops produces strong Dean drag forces along the whole loop but also induces an asymmetric Dean flow decay in the subsequent straight channel, thus producing rapid cross-sectional mixing flows that assist with 3D particle focusing. The use of out-of-plane loops favors a compact parallelization of multiple focusing channels, allowing one to process large amounts of samples. In addition, the low fluidic resistance of the channel network is compatible with vacuum driven flows. The resulting device is quite interesting for high-throughput on-chip flow cytometry.

Robust multiple focusing with adaptive time-reversal mirror using a genetic algorithm

Kim and Shin [J. Acoust. Soc. Am. 115 (2), 600-606 (2003)] suggested an extension of the single constraint adaptive time-reversal mirror (ATRM) to simultaneous multiple focusing, by considering multiple constraints. In their proposed method, the optimization is performed using the linearly constrained minimum variance (LCMV) method, a well known optimization method in the field of adaptive signal processing that allows multiple linear constraints. However, highly correlated signal vectors from the probe source locations cause prominent spatial sidelobes in multiple TR focusing. In this study, a genetic algorithm is extended to LCMV method to calculate the backpropagation vector which satisfies new constraint responses. Numerical simulations demonstrate that multiple TR focusing combined with a genetic algorithm can significantly suppress sidelobes, especially when the focal locations are close to each other.

Multiple Re-Reflections and Focusing of Waves by a Metamaterial Layer

Multiple Re-Reflections and Focusing of Waves by a Metamaterial Layer

MIMO through-wall radar 3-D imaging of a human body in different postures

This paper focuses on three-dimensional (3-D) imaging for the human body with different postures to enhance the situation awareness ability of through-wall radar. First, we design a two-dimensional MIMO array where the receiving antennas are uniformly and sparsely arranged in horizontal and vertical directions and four time-division multiplexing transmitting elements are placed at the four array corners. As a result, the equivalent aperture is closed to four times the size of the physical array. Second, an identical time-delay wall compensation algorithm attached to back-projection algorithm is presented to easily and approximately correct the image distortion caused by wall penetration, which employs an identical time-delay offset in the whole 3-D pixel-to-pixel imaging process to partially balance out multiple different focusing time-delay errors corresponding to multiple transmit-receive channels in each pixel. Finally, we develop a human body model with three typical postures in the FDTD simulation. Based on the MIMO array and the time-delay compensation algorithm, the simulated images created via the back-projection algorithm clearly provide the identifiable posture characteristics.

Multi-focus of modulated polarized Airy beam

The focusing performance of a modulated polarized Airy beam is explored by using the Richards and Wolf vectorial diffraction model in a high numerical aperture system. The multiple foca appeared on the focal plane or along the optical axis when a complex amplitude modulating function was introduced. Two focusing spots with long-focal-depth were additionally observed due to the Airy beam and complex amplitude modulation. The distance between the focuses were changed from 1.15λ to 3.56λ with FWHM of 0.9λ for one-dimensional linear polarized incident beam and from 1.15λ to 3.64λ for two-dimensional beam. The multiple focusing spots are expected to apply in the field of optical trapping and particle acceleration.

ISO 14001 in a corporate sustainability context: a multiple case study approach

Purpose – The purpose of this paper is to investigate the mechanisms through which ISO 14001 can contribute to the corporate sustainability. In this regard, the paper examines the underlying theoretical concepts and discusses the ISO 14001 in the context of the corporate sustainability. Additionally, the paper discusses the benefits of ISO 14001 from the perspective of the triple bottom line. Design/methodology/approach – The paper uses a multiple case study approach focusing on four ISO 14001-certified Slovenian organizations and two non-ISO 14001-certified organizations. The data collection methods included semi-structured questionnaire and interviews with managers in all studied organizations. Findings – It is suggested that the motives could be perceived as explanatory variables of the benefits realized from ISO 14001 certification. Further, the findings of this study indicate that environmental management system should be seen in a wider perspective that includes elements such as quality and social responsibility. Moreover, the results also lead us to the suggestion that there could be a reciprocal causal mechanism linking the environmental performance and economic performance. Practical implications – ISO 14001 can be an effective tool for pursuing sustainable development; however, organizations should move a step beyond ISO 14001’s environmental focus and recognize a multidimensional perspective by simultaneously addressing environmental, quality and social responsibility issues. Originality/value – The paper contributes to the corporate sustainability literature by investigating the mechanisms through which organizations can shift to more sustainable patterns using the ISO 14001.

Improved multiple focusing with adaptive time-reversal mirror in the ocean

The linearly constrained minimum variance (LCMV) method in adaptive signal processing is designed in such a way that it attempts to minimize the output power subject to constraints on the look directions. This adaptive method has been applied to time-reversal mirror (TRM) for simultaneous multiple focusing and its efficiency has been verified by [Kim et al., J. Acoust. Soc. Am. 109 (5), 1817–1825 (2001)]. However, the norm of the weighting vector ‖w‖ that satisfies the constraints tends to become very large when two probe sources (PS) are close to each other. It causes prominent spatial sidelobes as the weighting vector w is back-propagated in TR focusing. In this study, a relationship between ‖w‖ and PS locations is illustrated, and LCMV method is partially reformulated to calculate the weighting vector w which satisfies new constraint responses, so that sidelobes are significantly suppressed. The proposed method for improved adaptive time-reversal mirror for stable simultaneous multiple focusing is verified using numerical simulations and experimental data.

A Friend in Need: The Impact of the Syrian Civil War on Syria's Clients (A Principal-Agent Approach)

When a regional sponsor of militant movements experiences profound domestic instability, what happens to its clients? This paper explores this question by examining the case of Syria and its clients using a principal–agent approach. It examines three types of principal—single, collective, and multiple—focusing on the varying effects that these relationships have on the agents involved and arguing that each type of principal presents prospective agents with a trade-off between a loss of autonomy and a loss of internal cohesion. By comparing the effects of Syrian sponsorship on nonstate actors who have served as Syrian agents at various points in the evolution of the regime, I demonstrate that each type of principal has distinct advantages and risks for its agents. The paper concludes by outlining five possible outcomes of the current uprising in Syria for the Asad regime's clients, based on the uprising's impact on the regime as a principal.