Subtraction Mode Research Articles

Development of stopped-flow hyper-CEST NMR method on recirculating hyperpolarization system as applied to void space analysis in polymers.

129Xe NMR spectroscopy of polymers can provide important information on void spaces, sometimes called free volume, in polymers. Unfortunately, the spectroscopy's low sensitivity has limited its widespread use in both academic and industrial research. In order to overcome such a difficult situation, hyper-CEST method which employs hyperpolarization and CEST techniques, is examined after the introduction of recirculation and subtraction modes. Alongside the incorporated stopped-flow technique, these modes were very efficient in detecting very weak hidden signals from cellulose nanofiber (CNF) and silk fibroin (SF) films and in discussing the void space in these polymers. From the analysis of detailed saturation frequency dependence in the increment of 100Hz, the chemical shifts of hidden peaks were successfully determined to give reasonable values for the size of void space in CNF and SF. Application on thermoplastic polyurethane film also supported our method of analysis. The subtraction mode was very efficient in judging the presence or absence of any peak at a fixed saturation frequency. These facts support that the mode will surely be useful in the future exploratory study of very weak hidden signals.

Radiation reduction for interventional radiology imaging: a video frame interpolation solution

PurposeThe aim of this study was to diminish radiation exposure in interventional radiology (IR) imaging while maintaining image quality. This was achieved by decreasing the acquisition frame rate and employing a deep neural network to interpolate the reduced frames.MethodsThis retrospective study involved the analysis of 1634 IR sequences from 167 pediatric patients (March 2014 to January 2022). The dataset underwent a random split into training and validation subsets (at a 9:1 ratio) for model training and evaluation. Our approach proficiently synthesized absent frames in simulated low-frame-rate sequences by excluding intermediate frames from the validation subset. Accuracy assessments encompassed both objective experiments and subjective evaluations conducted by nine radiologists.ResultsThe deep learning model adeptly interpolated the eliminated frames within IR sequences, demonstrating encouraging peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM) results. The average PSNR values for angiographic, subtraction, and fluoroscopic modes were 44.94 dB, 34.84 dB, and 33.82 dB, respectively, while the corresponding SSIM values were 0.9840, 0.9194, and 0.7752. Subjective experiments conducted with experienced interventional radiologists revealed minimal discernible differences between interpolated and authentic sequences.ConclusionOur method, which interpolates low-frame-rate IR sequences, has shown the capability to produce high-quality IR images. Additionally, the model exhibits potential for reducing the frame rate during IR image acquisition, consequently mitigating radiation exposure.Critical relevance statementThis study presents a critical advancement in clinical radiology by demonstrating the effectiveness of a deep neural network in reducing radiation exposure during pediatric interventional radiology while maintaining image quality, offering a potential solution to enhance patient safety.Key points• Reducing radiation: cutting IR image to reduce radiation.• Accurate frame interpolation: our model effectively interpolates missing frames.• High visual quality in terms of PSNR and SSIM, making IR procedures safer without sacrificing quality.Graphical

High Speed Dual‐Band Photodetector for Dual‐Channel Optical Communications in Wavelength Division Multiplexing and Security Enhancement

AbstractThe forthcoming wireless networks must integrate to a high density of end‐user devices while ensuring a superior quality of service. It is imperative to devise solutions that reduce the density of wireless access points and associated costs, while simultaneously ensuring security and privacy throughout propagation. Herein, a novel dual‐band photodetector with high selective responsivities in distinct visible and near‐infrared (NIR) band is developed as an optical signal receiver. The receiver has an unprecedented fast switch speed > 500 kHz between different operation modes. Leveraging this fast switch speed, a high‐speed Multiple‐Input‐Single‐Output (MISO) system is developed, fusing spectrum resources from visible to infrared bands. The system achieves a data rate of 600 Kbps in the visible channel and 500 Kbps in the NIR channel, with a sum rate of 1.1 Mbps. This is the highest single‐channel data rate and sum rate among reported dual‐band photodetectors. Additionally, two previously overlooked mechanisms, the Subtraction and Addition modes, are studied in detail. The four operation modes are developed to establish a novel physical encryption method in terms of arithmetic relation. The dual‐channel coupled link can support a data rate of 200 Kbps, significantly enhancing communication security.

Differentiated Reception Modes Based Multiple Access

In recent years, the continuous increase in wireless data services and users’ traffic demand has been imposing great challenges on traditional multiple access control (MAC) methods. Some existing MAC techniques improve the communication system’s spectral efficiency (SE) via signal processing based cochannel interference (CCI) management. However, no interference management (IM) is free, i.e., its realization is based on the consumption of some communication resources, such as power and degree-of-freedom (DoF), which can also be used for the user’s desired data transmission. To lessen the resource cost for IM-based MAC, we exploit interactions among multiple wireless signals to propose a new MAC method, namely, Differentiated Reception Modes based Multiple Access (DRM-MA), in this paper. Under DRM-MA, a central control unit (CCU) is adopted to manage and pair multiple transmitting antennas with their serving receivers (Rxs). The CCU first calculates the phase difference of signals sent from each candidate antenna and perceived by the two receiving antennas of an Rx based on the locations of the transmitting antenna and Rx. Then, the CCU selects and pairs a proper transmitting antenna with each Rx, so that various Rxs can adopt either additive or subtractive reception mode to postprocess the signals received by its two antennas to realize in-phase desired signal construction and inverse-phase interference destruction. DRM-MA can avoid transmission performance loss incurred by signal processing-based IM. Our theoretical analysis and simulation results have shown that DRM-MA can enable concurrent data transmissions of multiple antenna-receiver pairs and output a high system’s SE.

Investigating the Perceptions of Sindhi Parents Towards Additive and Subtractive Bilingualism and Bilingual Education in Sindh, Pakistan

Pakistan is linguistically and culturally diverse country where more than 70 languages are spoken. Primary education in mother tongue is a basic human right of every child and this right has been denied in private education sector of the country. The division of education among private and public sectors have further pulled the tensions and division among the masses. Language in education policies have been not been dealt with serious consideration in the entire history of Pakistan. Further proliferation of private schools in Pakistan has sidelined the role of indigenous languages in educational domain especially at primary schooling. Private schools are teaching through the subtractive bilingualism mode where one language is being preferred over other languages in teaching and learning context . This paper intends to explore perceptions of Sindhi parents towards additive and subtractive bilingualism in private schools at primary schooling and how this one language policy in schools is affecting their children. For this purpose, 16 semi-structured interviews have been conducted through maximum variation sampling. The data is collected from four districts of the Sindh; Dadu, Hyderabad and Qambar & Shahdadkot. The results showed that parents hold different perceptions about additive/subtractive bilingualism. Out of 16 participants, 6 supported additive bilingualism and rest supported subtractive bilingualism. Results showed that parents were curious that English rather than helping create confusion and frustration for children at this very young age. Therefore, additive bilingualism must be supported that it not only facilitates children but also helps them to grasp complex concepts easily. They demanded that Mother tongue teaching must be supported in private schools Keywords: additive bilingualism, subtractive bilingualism, mother tongue education, English language teaching, language in education policy DOI: 10.7176/JLLL/84-03 Publication date: December 31 st 2021

Angiographic criteria for differential diagnosis of hemangiomas and arteriovenous malformations of different localization

Hemangiomas and microfistular arteriovenous malformations (AVMs) are vascular anomalies with high blood flow velocity. On angiographic examination, they look the same, in the form of a contrasting spot of varying degrees of intensity. A comparative analysis of the angiographic picture in dynamics, during the performance of subtraction angiography, allows for differential diagnosis and clearly identifies the type of vascular anomaly. Objective. to develop effective angiographic criteria for the differential diagnosis of hemangiomas and microfistular arteriovenous malformations (AVM) using subtraction angiography. Material and methods. Subtraction angiography of patients with congenital vascular anomalies based on 27 studies. Results. Analysis of angiographic data, performed in the subtraction mode, made it possible to identify characteristic angiographic differences between microfistular arteriovenous malformations and hemangiomas. The angiographic picture was studied in dynamics. The time between the onset of the arterial and venous contrasting phases, the duration of the parenchymal contrasting phase was calculated. In AVMs, outflow veins appear on the angiogram already in the first second of contrasting arteries due to rapid drainage of contrast through arteriovenous fistulas. The duration of contrasting the AVM shadow is no more than 2–3 seconds. Contrasting of the hemangioma parenchyma appears in the arterial phase at 2–3rd seconds and lasts for a long time from 3 to 10 seconds, due to a prolonged delay of the contrast medium in the cavernous structures of the hemangioma with late appearance of outflow veins. Conclusions. Performing and analyzing subtraction angiography in patients with congenital vascular anomalies allows instant differential diagnosis between hemangiomas and microfistular arteriovenous malformations without using additional examination methods. This increases the efficiency and quality of diagnostics of patients with vascular abnormalities, allows you to immediately transfer the diagnostic procedure to endovascular surgery. It makes the possible to provide specialized medical care to patients with hemangiomas and AVMs in one session, without additional endovascular intervention. Key words: hemangioma, arteriovenous malformation, differential diagnosis, angiography.

In situjet electrolyte micromachining and additive manufacturing

Jet electrolyte micromachining (JEMM) exploits water-jet-assisted electrochemistry to achieve metal processing with spatial localization, precision, and flexibility. Currently, JEMM enables both micromilling and deposition, with the manufacturing precision and efficiency limited by the preparation and installation of the microscale tool electrodes (typically > 100 μm). Here, we develop a facile and low-cost platform for integrated in situ micro-subtractive and additive JEMM. Our technology is capable of machining micrometric grooves and pillars with controllable length scales (>20 μm) and topologies (patterns or spatial geometries) on metallic substrates. The integrated platform pumps electrolyte toward a workpiece through a nozzle to perform multiple tasks on the same setup, including micronozzle tool preparation, subtractive manufacturing, and additive manufacturing. We achieve this by controlling electrode polarity and electrolyte. We demonstrate our platform for microfabrication of grooves having a variety of widths ranging from 20 to 100 μm when working in the subtractive JEMM mode. In the additive JEMM mode, we demonstrate the fabrication of complex three-dimensional high-aspect-ratio micropillars having customized geometries beyond what is currently available with conventional methods. The proposed technology enables precise, controllable, efficient, and scalable additive and subtractive micromanufacturing for a plethora of applications.

1/f noise analysis for FAST H i intensity mapping drift-scan experiment

ABSTRACT We investigate the 1/f noise of the Five-hundred-meter Aperture Spherical Telescope (FAST) receiver system using drift-scan data from an intensity mapping pilot survey. All the 19 beams have 1/f fluctuations with similar structures. Both the temporal and the 2D power spectrum densities are estimated. The correlations directly seen in the time series data at low frequency f are associated with the sky signal, perhaps due to a coupling between the foreground and the system response. We use singular value decomposition (SVD) to subtract the foreground. By removing the strongest components, the measured 1/f noise power can be reduced significantly. With 20 modes subtraction, the knee frequency of the 1/f noise in a 10-MHz band is reduced to $1.8 \times 10^{-3}\, {\rm Hz}$, well below the thermal noise over 500-s time-scale. The 2D power spectra show that the 1/f-type variations are restricted to a small region in the time-frequency space and the correlations in frequency can be suppressed with SVD modes subtraction. The residual 1/f noise after the SVD mode subtraction is uncorrelated in frequency, and a simple noise diode frequency-independent calibration of the receiver gain at 8-s interval does not affect the results. The 1/f noise can be important for H i intensity mapping, we estimate that the 1/f noise has a knee frequency (fk) ∼ 6 × 10−4 Hz, and time and frequency correlation spectral indices (α) ∼ 0.65, (β) ∼ 0.8 after the SVD subtraction of 30 modes. This can bias the H i power spectrum measurement by 10 per cent.

Electroless copper plating obtained by Selective Metallisation using a Magnetic Field (SMMF)

Lithography is the most commonly used method for the selective metallisation of non-conductive surfaces in the manufacture of electronic devices such as printed circuit boards and antennae. However, when used in subtractive mode, lithography results in the generation of large amounts of organic solvent and metal containing waste and requires high initial capital investment. For these reasons, additive methods of selective metallisation are being widely investigated. In this work, a novel additive approach of Selective Metallisation using a Magnetic Field (SMMF) was studied. This method uses a magnetic catalyst to initiate the electroless plating process. Magnetic catalyst particles composed of magnetite-silicon dioxide-silver were synthesised by a wet-chemical procedure. Their composition was analysed by scanning electron microscopy and energy dispersive X-ray spectroscopy and the phase formation was confirmed by X-ray diffractometry. Catalytic activity towards formaldehyde oxidation and the magnetic properties of particles were confirmed by cyclic voltammetry and vibrating sample magnetometry, respectively. The results showed that the particles can be used as a catalyst for electroless copper plating and are attracted by the magnetic field. The pattern of deposition of the magnetic catalyst is defined by the magnetic field. Two different configurations of magnet and substrate were used to deposit the catalyst dispersion onto the substrate surface. In both cases, the particles were attracted by the magnetic field and deposited exclusively where the magnetic field was applied. Subsequent electroless copper plating also only occurred at these areas. Parallel lines of electroless copper were obtained. The effect of the magnetic field on magnetic catalyst deposition and subsequent electroless plating was studied and key process-specific defects were identified.

Gain Optimization of Low-Profile Textile Antennas Using CMA and Active Mode Subtraction Method

This paper presents an active mode subtraction method based on the characteristic mode analysis to estimate the forward directivity based on the difference in modal significance curves. This made the optimization of the antenna gain in the design process to be more efficient. To the best of the authors' knowledge, such method is innovative and proposed in literature for the first time. This method is derived on the basis that the total radiated field of the antenna, and consequently, the directivity is mainly contributed by the excited dominant modes. To demonstrate its effectiveness, three compact, planar, and wearable antennas with increasing complexity will be designed and optimized using this method. The first is a conventional circular patch antenna operating at 5.3 GHz, whereas the second one is a planar loop antenna operating at 3.08 GHz. The third design is a crown-shaped planar antenna (CPA) with a 3 × 3 artificial magnetic conductor (AMC) plane integrated underneath to reduce potential coupling effects from the body. All three antennas are made fully using textiles with the same thicknesses: felt fabric as its substrate and ShieldIt Super as its conductive textile. For all designs, the use of the proposed method, which is validated using the method of moments, has predicted the maximum direction of radiation and its respective gain at the desired frequencies with good accuracy. Besides that, the design of the AMC plane for the CPA is also optimized using CMA prior to the integration with the antenna and a leather wrist strap. Measurements of the final crown-shaped antenna design indicated a good agreement with simulations, with an operating bandwidth of more than 240 MHz, FBR of 15.73 dB and a directional radiation pattern outward from the body.

Readiness of subtractive and additive manufacturing and their sustainable amalgamation from the perspective of Industry 4.0: a comprehensive review

The successful realization of Industry 4.0 depends much on how coherently the cyber and physical realms are conjoined in cyber-physical systems. In the context of the fourth industrial revolution, research efforts have mostly been channeled toward the cyber domain, whereas the physical domain has received significantly lesser consideration. A physical domain generally comprises material shaping equipment, work material, tools, working medium, sensors, automation technology, and connectivity mechanisms. The article provides a comprehensive review of the published literature to establish the states of readiness of the two most important manufacturing technologies: subtractive and additive and their sustainable merger from the perspective of Industry 4.0. Rich potentials in the four characteristics at the process level: speed, sustainability, agility, and customer centricity and three at the system level: connectivity, data collection, and automation are required for a manufacturing system (physical domain) to be Industry 4.0 compatible. The review establishes that the subtractive manufacturing domain is nearly compatible regarding speed and agility but needs improvements in respect of sustainability and customer centricity. Additive manufacturing, on the other hand, appears strong on agility and customer-centricity fronts but needs amelioration regarding production speed and sustainability. In respect of the system level characteristics, both technologies seem to be compatible regarding automation, whereas significant improvements are required in connectivity and data sensing and collection. For the sake of raising compatibility levels of the manufacturing systems, subtractive-additive amalgamation is scrutinized. The amalgamation, especially in a done-in-one configuration, has, reportedly, succeeded to retain the favorable traits of the two manufacturing technologies, thus, bringing the merger much closer to the Industry 4.0 requirements. Proper process planning and optimal work distribution between the subtractive and additive modes are critical for operating an amalgamated system at high levels of the key characteristics.

Oxygen-Permeable Films for Continuous Additive, Subtractive, and Hybrid Additive/Subtractive Manufacturing.

In the past 5 years, oxygen-permeable films have been widely used for continuous additive manufacturing. These films create a polymerization inhibition zone that facilitates continuous printing in the additive mode of fabrication. Typically, oxygen-permeable films made out of Teflon are currently used. These films are expensive and are not commonly available. Hence, this research work investigates the feasibility of using commonly available low-cost oxygen-permeable films made from polydimethylsiloxane (PDMS) and polyurethane for continuous additive manufacturing. We also characterize the ablation depth range that can be achieved using these films and the potential use for subtractive ablation-based manufacturing as well as hybrid additive/subtractive manufacturing. Results demonstrate that the PDMS films (600 μm thick) can be used for both additive and subtractive modes, whereas spin-coated PDMS thin film (40 μm thick) on glass coverslip and breathe-easy polyurethane film (20 μm thick) laminated on glass coverslip are suitable only for additive mode of fabrication. The latter two films are oxygen impermeable, however, they retain oxygen, which is capable of creating dead zone and thereby facilitates continuous printing. We anticipate that this work will help researchers to choose the appropriate oxygen-permeable film for continuous additive, subtractive, and hybrid additive/subtractive manufacturing of complex three-dimensional structures for a range of applications.

Leveraging Acoustic Signals for Fine-Grained Breathing Monitoring in Driving Environments

Given the increasing amount of time people spent on driving, the physical and mental health of drivers is essential to road safety. Breathing patterns are critical indicators of the wellbeing of drivers. Existing studies on breathing monitoring require active user participation of wearing special sensors or relatively quiet environments during sleep, which are hardly applicable to noisy driving environments. In this work, we propose a fine-grained breathing monitoring system, BreathListener, which leverages audio devices on smartphones to estimate the fine-grained breathing waveform in driving environments. By investigating the data collected from real driving environments, we find that Energy Spectrum Density (ESD) of acoustic signals can be utilized to capture breathing procedures in driving environments. To extract breathing patterns in ESD signals, BreathListener eliminates interference from driving environments in ESD signals utilizing background subtraction and Variational Mode Decomposition (VMD). After that, the extracted breathing pattern is transformed into Hilbert spectrum, and we further design a deep learning architecture based on Generative Adversarial Network (GAN) to generate fine-grained breathing waveform from the Hilbert spectrum of extracted breathing patterns in ESD signals. Experiments with 10 drivers in driving environments show that BreathListener can accurately capture breathing patterns of drivers in driving environments.

A sequence planning method for five-axis hybrid manufacturing of complex structural parts

The concept of additive–subtractive hybrid manufacturing provides a new idea for the manufacturing of high-precision complex structural parts. Currently, under the five-axis additive–subtractive hybrid manufacturing mode, existing research work concerned with sequence planning issues have limitations. This article presents a sequence planning method for hybrid manufacturing of complex structural parts with high precision. The initial printing direction of parts was determined based on an iterative search method and the initial hybrid manufacturing sequence was constructed by part volume decomposition, which solved the coupling problem of printing direction decision and machinability calculation. Under the constraint of tool accessibility, the whole planning of the hybrid manufacturing sequence was realized based on greedy algorithm. This method has achieved highly effective planning of the alternative sequence in the process of hybrid manufacturing, thus greatly reduced the number of tool changes required and laid a foundation for the realization of highly efficient hybrid manufacturing.

Infrared photoluminescence spectra measurements using boxcar integrator in the active baseline subtraction mode

A photoluminescence (PL) measurement method using boxcar integration in the active baseline subtraction mode has been implemented. It allows for infrared PL measurements with a low duty cycle of the pump pulse, thereby minimizing the uncontrolled heating of the structure under study. The implemented method was compared to phase-sensitive detection by signal-to-noise ratio of the resulting spectra, indicating its superior performance at low duty cycles. The decrease in uncontrolled heating of the structure under study was confirmed by observing a change in the ratio of temperature-sensitive PL peaks of a test InSb/InAs/InGaAs/InAlAs/GaAs nanoheterostructure.

Hybrid Laser Printing of 3D, Multiscale, Multimaterial Hydrogel Structures.

Fabrication of multiscale, multi-material three-dimensional (3D) structures at high resolution is difficult using current technologies. This is especially significant when working with hydrated and mechanically weak hydrogel materials. In this work, a new hybrid laser printing (HLP) technology is reported to print complex, multiscale, multimaterial, 3D hydrogel structures with microscale resolution. This technique of fabrication utilizes sequential additive and subtractive modes of material fabrication, that are typically considered as mutually exclusive due to differences in their material processing conditions. Further, compared to current laser writing systems that enforce stringent processing depth limits, HLP is shown to fabricate structures at any depth inside the material. As a proof-of-principle, a Mayan Pyramid with embedded cube-frame is printed using model synthetic polyethylene glycol diacrylate (PEGDA) hydrogel. Printing of ready-to-use open-well chips with embedded microchannels is also demonstrated using PEGDA and gelatin methacrylate (GelMA) hydrogels for potential applications in biomedical sciences. Next, HLP is used in additive and additive modes to print multiscale 3D structures spanning in size from centimeter to micrometers within minutes, which is followed by printing of 3D, multi-material, multiscale structures using this technology. Overall, this work demonstrates that HLP's fabrication versatility can potentially offer a unique opportunity for a range of applications in optics and photonics, biomedical sciences, microfluidics, soft robotics, etc.

A map-based method for eliminating systematic modes from galaxy clustering power spectra with application to BOSS

We develop a practical methodology to remove modes from a galaxy survey power spectrum that are associated with systematic errors. We apply this to the BOSS CMASS sample, to see if it removes the excess power previously observed beyond the best-fit $\Lambda$CDM model on very large scales. We consider several possible sources of data contamination, and check whether they affect the number of targets that can be observed and the power spectrum measurements. We describe a general framework for how such knowledge can be transformed into template fields. Mode subtraction can then be used to remove these systematic contaminants at least as well as applying corrective weighting to the observed galaxies, but benefits from giving an unbiased power. Even after applying templates for all known systematics, we find a large-scale power excess, but this is reduced compared with that observed using the weights provided by the BOSS team. This excess is at much larger scales than the BAO scale and does not affect the main results of BOSS. However, it will be important for the measurement of a scale-dependent bias due to primordial non-Gaussianity. The excess is beyond that allowed by any simple model of non-Gaussianity matching Planck data, and is not matched in other surveys. We show that this power excess can further be reduced but is still present using "phenomenological" templates, designed to consider further potentially unknown sources of systematic contamination. As all discrepant angular modes can be removed using "phenomenological" templates, the potentially remaining contaminant acts radially.

PC184 Delayed Conversion to Kissing Stent Configuration in the Setting of Unilateral Iliac Vein Stenting

Iliac vein stents are being increasingly used to treat chronic proximal venous outflow obstruction. Among patients with unilateral stenting in the proximal common iliac vein with extension into the inferior vena cava (IVC), a small number of patients presented with venous symptoms related to outflow obstruction of the contralateral common iliac vein. While the incidence of this complication of iliac vein stenting is unknown, this abstract presents one technical approach to this complication. We present 11 patients with outflow obstructive symptoms in the contralateral iliac vein after a prior IVC common iliac vein stent placement. Postanesthesia, ultrasound guidance is used to obtain access to the common femoral vein bilaterally. Inferior vena cavograms and venograms of the iliac veins are undertaken using contrast in digital subtraction mode. Intravascular ultrasound (IVUS) using a Volcano Visions PV .035 Digital IVUS catheter (Volcano Corporation, San Diego, Calif) is then used to evaluate the iliac veins and assess the degree of stenosis in each vein segment. The use of IVUS is critical to locate the narrow channel present between the contralateral stent and wall of the IVC, assist passage of the guidewire through this narrow channel, and ensure that the guidewire does not pass through the interstices of the stent (Fig 1). Balloon angioplasty is seldom necessary. The initial guidewire is then exchanged for a stiff 0.35-inch × 180-cm guidewire. Next, a 16-mm or 18-mm stent is positioned alongside the existing stent in a kissing iliac stents configuration. After the newly placed stent is deployed, both stents are simultaneously dilated with either 16-mm or 18-mm balloons (Fig 2). Finally, a completion venogram and IVUS confirm fully expanded stents. This procedure was performed in 11 patients (6 males, 5 females), with three performed on the right iliac vein and eight on the left iliac vein. The mean time to development of contralateral occlusive symptoms was 626 days from the initial stenting. Average follow-up time from the second stenting was 167 days, with no postoperative complications. Eight patients reported significant symptomatic improvement in their newly treated limb at 30 days postoperatively, while 10 patients did at 90 days postoperatively. No patients reported any worsening symptoms in either limb. Delayed conversion to a kissing stent configuration can be considered for treatment of contralateral iliac vein outflow obstruction in the setting of previous unilateral iliac vein stenting.Fig 2View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Unbiased contaminant removal for 3D galaxy power spectrum measurements

We assess and develop techniques to remove contaminants when calculating the 3D galaxy power spectrum. We separate the process into three separate stages: (i) removing the contaminant signal, (ii) estimating the uncontaminated cosmological power spectrum, (iii) debiasing the resulting estimates. For (i), we show that removing the best-fit contaminant mode subtraction), and setting the contaminated components of the covariance to be infinite (mode deprojection) are mathematically equivalent. For (ii), performing a Quadratic Maximum Likelihood (QML) estimate after mode deprojection gives an optimal unbiased solution, although it requires the manipulation of large $N_{\rm mode}^2$ matrices ($N_{\rm mode}$ being the total number of modes)}, which is unfeasible for recent 3D galaxy surveys. Measuring a binned average of the modes for (ii) as proposed by \citet*[FKP]{Feldman} is faster and simpler, but is sub-optimal and gives rise to a biased solution. We present a method to debias the resulting FKP measurements that does not require any large matrix calculations. We argue that the sub-optimality of the FKP estimator compared with the QML estimator, caused by contaminants is less severe than that commonly ignored due to the survey window.

Multimode theory of single-photon subtraction

We develop a general theory to describe the manipulation of a multimode quantum state of light via the subtraction of a single photon. The theory is applicable for various types of subtraction schemes independent of the physical nature of the light modes, their number or the embedded quantum states. We show that different subtraction schemes can be described in a unified approach through the characterization of their intrinsic subtraction modes. The conditional state of the multimode quantum light after the photon subtraction is defined by the number of subtraction modes and their matching with the light modes. We propose the manipulation of light states by controlling the subtraction modes. Performing a photon subtraction on a multimode quantum resource is promising for the implementation of a number of quantum information protocols in all-optical, multiplexed and scalable way.