Phase Factor Research Articles

Calibration of spatially modulated snapshot imaging polarimeter based on phase-shift interferometry.

The snapshot imaging polarimeters (SIPs) using spatial modulation have gained increasing popularity due to their capability of obtaining all four Stokes parameters in a single measurement. However, the existing reference beam calibration techniques cannot extract the modulation phase factors of the spatially modulated system. In this paper, a calibration technique based on a phase-shift interference (PSI) theory is proposed to address this issue. The proposed technique can accurately extract and demodulate the modulation phase factors through measuring the reference object at different polarization analyzer orientations and performing a PSI algorithm. Using the snapshot imaging polarimeter with modified Savart polariscopes as an example, the basic principle of the proposed technique is analyzed in detail. Subsequently, the feasibility of this calibration technique was demonstrated by a numerical simulation and a laboratory experiment. This work provides a different perspective for the calibration of a spatially modulated snapshot imaging polarimeter.

BUDGET EXECUTION IN PUBLIC PROCUREMENT PROCESSES OF GOODS AND SERVICES OF A HIGHER POLYTECHNICAL SCHOOL. CHIMBORAZO, 2023

The development of the research focused on the design of a proposed plan for budget execution with a predictive impact that allows improving the processes of public procurement of goods and services in a Higher Polytechnic School of Chimborazo for the year 2023. Type of basic study and projective with a cross- sectional, non-experimental design, predictive and prospective scope, attending levels of knowledge of less descriptive and explanatory complexity, population of 80 surveyed employees. Budget Execution, Budget Certification and Applicable Regulations with scope at High level, while Obligations and Establishment of commitments with Medium or low levels. The risk factors for the Precontractual phase are the Budget item, Responsibility for execution and the Commitments for payments and, for the Contractual phase, the Budget Directive, Responsibility for execution and the Budget Reform. Global, are risk s of public procurement processes, Responsibility for execution and Budget reform. In this regard, a guide plan for the correct management of internal technical procedures at the Polytechnic School of Chimborazo was presented to ensure public procurement associated with goods and services.

Global Public Debt Since 1995: Long-Term Trends, Current Phase, Medium-Term Outlook for Economic Growth

Topic. The paper aims to identify long-term trends in global public debt (since 1995), provide its current overview (the magnitude of debt, concentration levels among participants and instruments, risk factors in the current phase of debt accumulation) and estimate its impact on global economic development over the medium term. This analysis has significant scientific and practical relevance due to the unprecedented character of factors affecting global level of indebtedness in the past few years (the Covid-19 pandemic since 2020 and the biggest military conflict in Europe since the Second World War since 2022). Methods. The main sources for the research were reports, outlooks and data bases of national regulators and international organizations (International Monetary Fund, World Bank, Bank for International Settlements, Organization for Economic Co-operation and Development) concerning public debt, research in this field conducted by leading research centers and financial market participants. Results. Two major periods in global debt development over time are shown: 1995 – 2007-08 with stable relative global public debt level, and since 2008 – rising levels of public debt. High levels of concentration in the global debt market and even in higher degree the government securities market are analyzed. These markets are characterized by the highly uneven distribution of debt among advanced and developing economies, state and local governments (central governments are main borrowers), instruments (predominantly global debt is issued through bonds nominated in domestic currencies with a straight fix rate). Risk factors in the current (since 2010) wave of global debt accumulation are described: 1. the magnitude of accumulated debt, its higher rate of growth and distribution among countries; 2. debt accumulation during a prolonged period of weak economic growth and investment activity in the 2010s; 3. the consequences of Covid pandemic and the military conflict in Ukraine. Economic repercussions of a high level of the country’s indebtedness, including its threshold level, are shown. Many key participants of the global public debt market (especially advanced economies) are exposed beyond such threshold. Policy tools for reducing public debt are listed. Preliminary estimates of the medium-term impact of the global debt market conjuncture on global economic development are given. The existence of self-amplifying risks of global stagflation and public debt crisis is revealed. Discussion. The impact of extraordinary factors affecting economic development in the world from 2020 on the global public debt market requires further research.

Passive synthetic aperture for direction-of-arrival estimation using sparse Bayesian learning

Passive synthetic aperture (PSA) extension for a moving array has the ability to enhance the accuracy of direction-of-arrival (DOA) estimation by constructing a larger virtual aperture. The array element overlap in array continuous measurements is required for the traditional extended towed array measurement (ETAM) methods. Otherwise, the phase factor estimation is biased, and the aperture extension fails when multiple sources exist. To solve this problem, passive aperture extension with sparse Bayesian learning (SBL) is proposed. In this method, SBL is used to simultaneously estimate the phase correction factors of different targets, followed by phase compensation applied to the extended aperture manifold vectors for DOA estimation. Simulation and experimental data results demonstrate that this proposed method successfully extends the aperture and provides higher azimuth resolution and accuracy compared to conventional beamforming (CBF) and SBL without extension. Compared with the traditional ETAM methods, the proposed method still performs well even when the array elements are not overlapped during the motion.

Difference frequency coherent matched autoproduct processing for source localization in deep ocean

Matched autoproduct processing (MAP) refers to a matched field processing (MFP) style array signal processing technique for passive source localization, which interrogates frequency-difference autoproduct instead of genuine acoustic pressure. Due to frequency downshifting, MAP is less sensitive to environmental mismatch, but it suffers from low spatial resolution and a low peak-to-sidelobe ratio of ambiguity surface. These source localization metrics are herein improved with coherent approaches. Specifically, the coherent normalized MFP is extended to coherent matched autoproduct processing (CMAP), a difference frequency coherent algorithm that exploits correlations among the autoproducts at various difference frequencies and eliminates the phase factor of the source spectrum for passive source localization. Phase-only coherent matched autoproduct processing is a CMAP derivation technique that only uses phase information. Through simulations in a Munk sound-speed profile environment, sensitivity analysis in the South China Sea environment, and high signal-to-noise ratio experimental measurements, these two algorithms are validated as compared to the conventional MFP and incoherent MAP. Simulation investigations demonstrate that difference frequency coherent algorithms can suppress sidelobes while simultaneously enhancing the localization resolution and robustness. The experimental results generally support the findings of the simulations.

A Statistical Analysis of the Factors with Nonrandom Impact on the Survival Rate of Women with Breast Cancer, by Type of Medical Treatment

A statistical analysis of the factors with nonrandom impact of the survival rate of women with breast cancer, by type of medical treatment in Ukraine, was made using data from the National Cancer Register. The complexity and ambiguity of the problem related with the choice of a special treatment type, i. e. surgical treatment or combined surgical treatment, was emphasize. The combined surgical treatment is available in two options: as a combination of surgical treatment and radiation therapy and a combination of surgical treatment, radiation therapy and chemical therapy. The data on female patients who had medical treatment in the National Institute of Cancer used for a statistical analysis to reveal positive and negative results from each type of special medical treatment. 
 The need for the assumption on proportionality was substantiated, with its testing based on a graphic analysis by grouping factors. The obtained results led to the conclusion that the model could be extended by the categorical factors: type of treatment (grouping factor), type of surgical operation, phase of decease.
 The assessment was made based on analyzing the factors’ impact by type of medical treatment. It was demonstrated that the model could be extended by interaction effects that would enable for estimating the relative risk depending on a combination of the treatment group and the respective factor. None of the effects included in the model could prove to be statistically significant. It means that no conclusions could be made about the factors’ interactions by type of the medical treatment. The interpretation of all the other factors that proved to be significant was applied to all the population. The strongest projection weight in the model was with the factor of decease phase, followed by the type of medical treatment and, in equal proportions, by the age and the type of surgical operation. The results of checking the global test could demonstrate the feasibility of predicting the survival rate for the overall model with the significance level equal to 0.05.
 It was proved that adjuvant and chemical therapies could reduce the risks of the recurrence, but this result had not an ultimate statistical validity. Despite of the positive non-recurrence result, the survival rate by groups still reduces, being an obvious effect of the abovementioned groups of medical treatment.

Optical multiqubit gate operations on an excitation-blockaded atomic quantum register

We consider a multiqubit system of atoms or ions with two computational ground states and an interacting excited state in the so-called blockade regime, such that only one qubit can be excited at any one time. Examples of such systems are rare-earth-ion-doped crystals and neutral atoms trapped in tweezer arrays. We present a simple laser excitation protocol that yields a complex phase factor on any desired multiqubit product state, and which can be used to implement multiqubit gates such as the $n$-bit Toffoli gates. The operation is performed using only two pulses, where each pulse simultaneously address all qubits involved in the operation. By relying on the well-established complex hyperbolic secant pulse shape, our scheme is also robust and permits complete transfers to and from the excited states despite variations in Rabi frequencies and transition frequencies. A detailed analysis of the multiqubit gate performance is provided.

Goos–Hänchen and Imbert–Fedorov shifts for rotational elliptical Gaussian beams impinging on graphene–substrate surfaces

This paper derives the analytical solution of Goos–Hänchen and Imbert–Fedorov shifts of rotational elliptical Gaussian beams (REGBs). Furthermore, we find that near the Brewster angle incidence at near-p incident paraxial beam polarization, the values of the beam shifts and the widths of the corresponding resonance shift curves become dependent on the beam waist. By introducing the effective beam waist and rotational phase factor, the causes of the beam shift variation phenomenon are analyzed from the viewpoints of analytical solutions and Fourier optics. Meanwhile, by adjusting the Fermi energy level of graphene, it is found that the direction of GH shift of the elliptical rotating Gaussian beam depends on the reflecting material, and the direction of IF shift depends on the rotational phase of the beam.

Experimental study of distribution and quantitative characterization of discontinuous oil phase based on micro-CT

When a sandstone reservoir enters the ultra-high water cut stage, the oil phase changes from continuous to discontinuous, which results in difficulties in the further development and utilization of the reservoir. It is important to clarify the flow law and distribution state of discontinuous oil phases to guide the remaining oil production. This study selected samples from sandstone reservoirs, accurately obtained oil and water phase information from digital core, and constructed matrix based on three-dimensional CT scanning to study the law of discontinuous oil phase distribution. We used digital cores to construct pore network models and calculate the pore radius, throat radius, pore-throat ratio, coordination number, and tortuosity to study the influence of pore structure on discontinuous oil phase flow law. A micro-displacement experiment consisting of two phases of simulated reservoir and development was designed. To improve the accuracy of the experiment, the related pressure was controlled to form bound water in the simulated reservoir formation stage. In the simulated reservoir development phase, in situ scanning of cores at different displacement stages was performed to obtain oil and water distributions at different stages in the same location. The number of oil droplets, 3D shape factor, Euler number, and saturation coefficient of the oil phase were calculated, and the micro-remaining oil clumps were quantitatively analyzed. According to the morphology and distribution characteristics, the remaining oil of the discontinuous phase was divided into the types of the throat, film, droplet, island, and corner. The results showed that the sample with a small pore-throat ratio, large coordination number, and small tortuosity was more likely to form dominant channels; moreover, the remaining oil was more concentrated in this state. In the remaining oil of the discontinuous phase, the number of droplets was the largest and had an obvious displacement effect. The island number was small because the selected samples had good connectivity and it is difficult to form large oil droplets in a single pore. In the ultra-high water cut stage, the throat number increased slowly, which was related to the formation of dominant channels. The corner and the film were difficult to displace; thus, their numbers increased steadily. The quantitative characterization of the discontinuous oil phase is helpful for further study of remaining oil at the pore scale.

Protective Activity against Oxidative Stress in Dermal Papillae with Extracted Herbal Essential Oils

Dermal papilla cells (DPCs) are a rich source of nutrients and secrete multiple growth factors that can affect hair growth. As oxidative stress leads to hair loss in humans, it is considered to be one of the factors that can impair the function of DPCs. Herb-derived phytochemicals exhibit potent antioxidant activities; therefore, this study investigated whether a set of essential oils (lavender, lemongrass, rosemary, and chamomile oils) promote the hair-growth activity of DPCs. Intracellular reactive oxygen species (ROS) increased markedly in ultraviolet B-irradiated DPCs (50 mJ/cm2) and were efficiently blocked by essential oils. Essential oils upregulated the mRNA and protein levels of phase II enzymes (detoxifying and antioxidant), including heme oxygenase-1, NAD(P)H quinone oxidoreductase-1, and glutathione S-transferase pi. They also upregulated and activated nuclear factor E2-related factor 2, an essential transcription factor for phase II enzymes. Regarding biomarkers for hair growth, essential oils significantly increased vascular endothelial cell growth factor and insulin-like growth factor-1 mRNA levels. In conclusion, phytochemicals in essential oils enhance hair growth through ROS-scavenging activity in DPCs.

Triple- Q partial magnetic orders induced by quadrupolar interactions: Triforce order scenario for UNi4B

We theoretically investigate possible symmetry-broken states in ${\rm UNi_4B}$, constructing a localized pseudo triplet crystalline-electric field model. For a long time, its low-temperature symmetry-broken phase in ${\rm UNi_4B}$ has been considered to be a magnetic toroidal order forming atomic-scale vortices lattice with disordered sites at each center of the vortices. However, recent observation of current-induced magnetizations offers a reinvestigation about the validity of this order parameter because of the contradiction in their anisotropy. Our model takes into account the quadrupole degrees of freedom, whose importance is recently evidenced by the sound-velocity softening. We find that the quadrupole moments play an important role in determining the magnetic structure in the ordered states. For a wide range of parameter space, we obtain two triple-$\mathcal{Q}$ magnetic orders in our 36-site mean-field analysis: toroidal order and another one with the same number of disordered sites as in the toroidal order. We name the latter ``triforce'' order after its magnetic structure. Importantly, the triforce order possesses exactly the same spin structure factor as the toroidal order does, while the phase factors in the superposition of the triple-$\mathcal{Q}$ structure are different. We show that the triforce order is consistent with the observed current-induced magnetization when the realistic crystal structure of ${\rm UNi_4B}$ is taken into account. We compare the predictions of the triforce order with the experimental data available at present in detail and also discuss possible applications of the present mechanism of triple-$\mathcal{Q}$ orders to anisotropic correlated systems.

Generation and manipulation of pure spin current in a conducting loop coupled to an Aharonov–Bohm ring

In this work we put forward a new prescription for the generation and manipulation of non-decaying pure spin current (SC) in a Rashba spin–orbit (SO) coupled conducting loop which is attached to an Aharonov–Bohm (AB) ring. In presence of a single link between the rings, a SC is established in the flux-free ring, without accompanying any charge current (CC). The magnitude and direction of this SC are controlled by means of the AB flux, without tuning the SO coupling, which is the central aspect of our study. Employing a tight-binding framework we describe the two-ring quantum system, where the effect of magnetic flux is incorporated through Peierls phase factor. The specific roles of AB flux, SO coupling and the connectivity among the rings are critically investigated which yield several non-trivial signatures in energy band spectrum and pure SC. Along with SC, the phenomenon of flux-driven CC is also discussed, and at the end, different other effects like electron filling, system size and disorder are analyzed to make the present communication a self contained one. Our detailed investigation may provide some key aspects of designing efficient spintronic devices where SC can be guided in an other way.

Optimization of Partial Transmit Sequences for PAPR Reduction of OFDM Signals Without Side Information

This paper develops a novel optimization of partial transmit sequences (PTS) with phase quantization to reduce the peak-to-average-power ratio (PAPR) of orthogonal frequency-division multiplexing (OFDM) signals and enable data detection without side information. Since the formulated optimization problem is non-convex and has exponential time complexity, we employ a convex relaxation method to convert the original optimization problem into a series of convex programming whose solutions converge to a sub-optimal point satisfying the Karush-Kuhn-Tucker (KKT) conditions in polynomial time. Moreover, the obtained phase factors are quantized to enable the maximum likelihood (ML) phase estimation at the receiver, hence removing the need of sending side information. Analytical and numerical results are provided to show that our proposed PTS design achieves better PAPR reduction over existing PTS methods, while no performance degradation is incurred in data detection when the number of phase factors is properly chosen.

Sacral neuromodulation in the management of non-obstructive urinary retention: Test phase and predictive factors.

The aim of this study is to evaluate the success of the test phase of sacral neuromodulation in management of chronic non-obstructive urinary retention and the factors predictive of good response. This is a retrospective study carried out on a cohort of patients followed up in a tertiary University Hospital in France. Fifty-two patients with chronic non-obstructive urinary retention were included in this study. These patients were seen over the past 20 years, from the year 2000 to 2020. The initial evaluation of patients included a summary of medical and surgical history, age, BMI, history of pelvic floor disorders, initial voiding pattern, physical examination, voiding diary, initial uroflowmetry and a urodynamic study. Postoperative follow-up and analysis of complications were also carried out. A total of 52 patients were included in this study, 13 males and 39 females. Out of these patients, 17 patients (32.7%) with a median age of 47.3 years±18.1 benefited from definitive implantation of the sacral neuromodulation. The univariate analysis showed that age was the only significant variable in this study and the optimal age threshold was<58.5 years. SNM is a therapy with significant clinical benefits and low morbidity for patients with chronic non-obstructive urinary retention. The results obtained need to be confirmed with a prospective study with a larger number of patients.

Improving efficiency of the path optimization method for a gauge theory

We investigate efficiency of a gauge-covariant neural network and an approximation of the Jacobian in optimizing the complexified integration path toward evading the sign problem in lattice field theories. For the construction of the complexified integration path, we employ the path optimization method. The $2$-dimensional $\text{U}(1)$ gauge theory with the complex gauge coupling constant is used as a laboratory to evaluate the efficiency. It is found that the gauge-covariant neural network, which is composed of the Stout-like smearing, can enhance the average phase factor, as the gauge-invariant input does. For the approximation of the Jacobian, we test the most drastic case in which we perfectly drop the Jacobian during the learning process. It reduces the numerical cost of the Jacobian calculation from ${\cal O}(N^3)$ to ${\cal O}(1)$, where $N$ means the number of degrees of freedom of the theory. The path optimization using this Jacobian approximation still enhances the average phase factor at expense of a slight increase of the statistical error.

Deviation to the Tri-Bi-Maximal flavor pattern and equivalent classes

In the model-independent context, the neutrino mass matrix is assumed to be diagonalized by means of a unitary matrix that possesses the Tri-Bi-Maximal (TBM) flavor mixing pattern. We present an analysis where the TBM deviation is explored by considering different forms with texture zeros, for the charged lepton mass matrix. These last mass matrices are classified into equivalent classes. We are interested in the charged lepton mass matrices with the minimum free parameter number, i.e. the maximum number of texture zeros, that allows us to correctly reproduce the reactor mixing angle value. We show a deviation from the TBM pattern in terms of the charged lepton masses as well as the theoretical expressions and their parameter space for the mixing angles. Finally, we present the phenomenological implications of numerical values of the “Majorana-like” phase factors on the neutrinoless double-beta decay.

Entanglement transmission due to the Dzyaloshinskii–Moriya interaction

We revisited the effectiveness of state and entanglement transmission through a spin-chain-based quantum channel while altering the system parameters and the channel’s initial state. Our research is focused on the spin-1/2 XX chain with Dzyaloshinskii–Moriya (DM) interaction and the aim is to measure entanglement dynamics between different part of the chain. The speed of entanglement propagation is utilized to probe the evolution of the system via three scenarios: (i) pure Heisenberg interaction, (ii) pure DM interaction, and (iii) collaboration of both types of couplings. To accomplish this, we employ the fermionization approach to obtain an exact solution to the problem. Aside from investigating the influence of magnetic interaction type on entanglement transfer, the effect of selecting the initial state has also been studied. As a result, we discovered that the phase factor regulating the system’s initial state induces sharp drops in the propagation speed of entanglement. We also showed how to predict the location of these dramatic drops using the language of wave interference. In addition, the fastest transmission occurs at a special value of the phase factor in which the highest amount of entanglement reaches the system’s different pairs. On the other hand, we observe a continuous and flat range of this factor in which the least amount of entanglement is transmitted and for them we have a sharp drop in the speed profile.

Analyzing Customers’ Demands for Different Housing Features in Buildings Using a Data Mining Method

There are many options and factors in the production phase of housing. In the marketing phase, houses are presented to the customer’s taste. Therefore, it is clear that a customer-oriented approach is necessary to establish a supply–demand balance in housing production on the basis of quality. This study aimed to determine customers’ housing demands in the construction sector. Within the scope of the study, 303 surveys were conducted in 30 different provinces of Turkey. The data obtained were analyzed by WEKA software with association rule extraction as the data mining method. The distribution of other attributes was determined according to two different class labels, namely the ownership status of the houses (tenant or homeowner) and customers’ expectations of the houses. As a result of the study, it is clear that people living in Turkey prefer a south-facing facade when purchasing a house. In addition, it is seen that the property owners demand 4 + 1 independent units. It is remarkable that individuals who are tenants want the living room to be spacious. The results of the study also revealed that female individuals have higher expectations of housing than male individuals. At the same time, it is understood that people’s expectations of housing differ according to the variables of age, education level, and the number of family members. The majority of the results in this study had a confidence value of 90% and above. This study was intended to serve as a guide for housing developers in Turkey to better understand and meet the demands of buildings’ residents.

Open quantum system approach for heavy quark thermalization* *Supported by the National Natural Science Foundation of China (12175165, 11705125)

We treat heavy quark as an open quantum system in a hot medium and rederive the stochastic Schrödinger equation (SSE) from the full Schrödinger equation for both heavy quarks and the medium. We apply the SSE to the dynamical evolutions of a heavy quark (as a system) in the static hot medium (as an environment). Heavy quarks interact with the medium via random scatterings, which exchange the momentum and phase factor randomly between two wave functions of the system and the environment. The exchange of momentum and phase factor results in the transition between different eigenstates of the system. These are included via an external stochastic potential in the Hamiltonian of SSE. Stochastic wave functions of a heavy quark are evolved with the stochastic external potential. The mean wave functions and corresponding momentum distributions of heavy quarks are obtained after the ensemble average over a large set of stochastic wave functions. We present the thermalization of heavy quarks in the static medium with different coupling strengths.

Cognitive and psychological outcomes and follow-up in severely affected COVID-19 survivors admitted to a rehabilitation hospital.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) represents the most recent severe pandemic resulting in coronavirus disease 2019 (COVID-19). COVID-19 can damage the central nervous system, requiring admission to intensive care units (ICU) and aggressive treatments (long-term ventilatory assistance and sedation) to stabilize vitals. Most post-COVID-19 patients experience cognitive impairments and mood or stress disorders. We aimed to study the frequency of cognitive deficits in COVID-19 survivors, the relationship between clinical factors in the acute phase and cognitive outcomes, affective states, and quality of life. We explored cognitive reserve (CR) role, as a post-COVID-19 resilience factor. Twenty-nine COVID-19 inpatients were assessed using a neuropsychological battery, mood scales, quality of life, and social integration questionnaires. Twenty-five were retained through telephone follow-up to monitor cognitive sequelae, affective states, and reintegration levels roughly 8months after hospital discharge. We administered the Cognitive Reserve Index questionnaire. We found most patients display no cognitive deficits. When they did, multi-domain impairment occurred most frequently, especially involving executive functions. Results revealed a significant correlation between depression levels and the interval between ICU admission and tracheal tube removal. We found increased levels of depression and anxiety at follow-up, a significant relationship between resuming daily life activities, high CR, and executive functions. These findings suggest the importance of psychological support in the long term and the modulating role of cognitive reserve in quality of life after infection.