Where is the orbital angular momentum in vortex superposition states?

In this paper, we explore the distribution of the orbital angular momentum (OAM) in the coaxial vortex superposition states based on the independent propagation principle of light in this interference process. We find that in this case, some specific singular points exist in the spatial intensity distribution. The first type of singular point is located at the center point of the spatial intensity distribution. The second type of specific singular point is at the critical location of the overlapping area in angular direction. By analogy with the angular momentum superposition of two axially rotating homogeneous disks with different radius in rigid body, We present a suggestion: the center point is located at the overlapping area of all the superposed components. Therefore, the topological charge value in the center point should be doubled by the actual number of superposition field components. The singular point at the critical location of the overlapping area in angular direction should also be co-owned by the superposition components outside the position of the ring (including the corresponding component of the ring). The total OAM is exactly equal to the sum of those two types contained in the superposition states, which is equal to the input OAM of the superposition state components. The conservation of the OAM in the coaxial interference process is demonstrated.

When optical vortex array meets cycloid.

Optical vortex arrays (OVAs) have drawn widespread attention owing to their multiple optical vortices and higher dimensions. However, existing OVAs have not yet been utilized to exploit the synergy effect as an entire system, particularly for manipulating multiple particles. Thus, the functionality of OVA should be explored to respond to application requirements. Hence, this study proposes a functional OVA, called cycloid OVA (COVA), based on a combination of cycloid and phase-shift techniques. By modifying the cycloid equation, multiple structural parameters are designed to modulate the structure of the COVAs. Subsequently, versatile and functional COVAs are experimentally generated and modulated. In particular, COVA executes local dynamic modulation, whereas the entire structure remains unchanged. Further, the optical gears are first designed using two COVAs, which exhibit potential for transferring multiple particles. Essentially, OVA is endowed the characteristics and capacity of the cycloid when they meet. This work provides an alternative scheme to generate OVAs, which will open up advanced applications for the complex manipulation, arrangement and transfer of multiple particles.

Polarization helicity and the optical spin-orbit Hall effect.

The optical spin-orbit Hall effect manifests the separation of the spin angular momentum (SAM) and the orbital angular momentum (OAM), yet it can be obtained for the radially polarized light and well controlled by the initial phase of the polarization state which leads to the twist of its distribution. In this paper, we introduce the polarization helicity to characterize the effect of the initial phase of the polarization states in the optical spin-orbit Hall effect. We find the polarization helicity of the radial polarization state can be modulated by changing its initial phase, and the polarization helicity of the high-order polarization state always is zero. We show that the separation magnitude of the SAM and the OAM reach the maximum value when the initial phase of the radial polarization state equals π/4 (or -π/4). The sign of the SAM and the OAM are determined by the polarization helicity of incident light and the anisotropy of uniaxial crystal, and its evolution follows a sinusoidal function. Furthermore, the polarization state of the incident radially polarized light will evolve into the left-handed (or right-handed) elliptical polarization state as the change of the polarization helicity of incident light. Our studies further deepen the understanding of the spin-orbit coupling of the vector beams, and provide a potential technique for modulating the polarization state of the light in uniaxial crystal.

Quantum interference in anti-parity-time symmetric coupled waveguide system.

We theoretically demonstrate quantum interference in an anti-parity-time (anti-PT) symmetric system based on coupled waveguides. We calculate the coincidence probability in an input polarization-entangled two-photon state, which can be used to simulate different statistical particles. When the birefringence of the waveguides is negligible, our results indicate that the coincidence probabilities of the bosons and fermions decrease exponentially with the propagation distance in both the unbroken and broken anti-PT symmetry regions owing to the dissipation. Particularly, loss-induced transparency is observed for the bosons. Simultaneously, the statistical rule valid in the Hermitian system is violated and the antibunching of bosons is observed. When the birefringence of the waveguides is considered, the coincidence probability of the bosons and fermions is equalized at the exceptional point (EP), whereas that of the bosons is less(greater) than that of the fermions in the broken(unbroken) anti-PT symmetry region. Additionally, we observe the Hong-Ou-Mandel dip for bosons in the broken anti-PT phase. Our research provides a complementary technique for the manipulation of quantum interference compared with the PT symmetric system and may be applied in building quantum devices with anti-PT symmetric quantum mechanics.

Trans-spectral vector beam nonlinear conversion via parametric four-wave mixing in alkali vapor.

Coherent frequency conversion of vector beams (VBs) without distorting their intensity profile or spatial polarization distribution is important for novel applications in quantum and classical regimes. Here, we experimentally and theoretically investigate VB transfer from near-infrared to blue light using a Sagnac interferometer, combining the parametric four-wave mixing process in atomic vapor. The vector probe beam is converted into a completely different wavelength, and the vector mode of the generated blue beam is highly similar to the incident probe beam. These results may provide a feasible solution for communication interfaces in classical and quantum science fields based on atomic ensembles.

Collapse of hybrid vector beam in Rb atomic vapor.

In recent years, many researchers have tried to control and design the collapsing behavior of light beams in nonlinear media. Vector beams coupling with spin and orbit angular momentum freedom have attracted more and more attention. In this Letter, we study the collapse of a hybrid vector beam (HVB) propagating through rubidium atomic vapor. First, the HVB collapses into filaments located at positions with linear polarization. As propagation distance in atomic vapor increases, the locations of the filaments switch from positions with linear polarization to those with circular polarization. In this process, the absorption of the medium plays an important role. Results indicate that the absorption can be used as a degree of freedom to modulate the filamentation. Furthermore, by analyzing the polarization angle of an elliptically polarized position on the transverse plane of the HVB, we demonstrate the evolution of polarization distribution of HVB during propagation. Such results could have application in manipulating other structured beams and could be potentially applied to realize optical switches or logic for information processing.

Review of social networks of professionals in healthcare settings-where are we and what else is needed?

BACKGROUND: Social Network Analysis (SNA) demonstrates great potential in exploring health professional relationships and improving care delivery, but there is no comprehensive overview of its utilization in healthcare settings. This review aims to provide an overview of the current state of knowledge regarding the use of SNA in understanding health professional relationships in different countries. METHODS: We conducted an umbrella review by searching eight academic databases and grey literature up to April 30, 2021, enhanced by citation searches. We completed study selection, data extraction and quality assessment using predetermined criteria. The information abstracted from the reviews was synthesized quantitatively, qualitatively and narratively. RESULTS: Thirteen reviews were included in this review, yielding 330 empirical studies. The degree of overlaps of empirical studies across included reviews was low (4.3 %), indicating a high diversity of included reviews and the necessity of this umbrella review. Evidence from low- and middle-income countries (LMIC), particularly Asian countries, was limited. The earliest review was published in 2010 and the latest in 2019. Six reviews focused on the construction or description of professional networks and seven reviews reported factors or influences of professional networks. We synthesized existing literature on social networks of health care professionals in the light of (i) theoretical frameworks, (ii) study design and data collection, (iii) network nodes, measures and analysis, and (iv) factors of professional networks and related outcomes. From the perspective of methodology, evidence lies mainly in cross-sectional study design and electronic data, especially administrative data showing "patient-sharing" relationships, which has become the dominant data collection method. The results about the impact of health professional networks on health-related consequences were often contradicting and not truly comparable. CONCLUSIONS: Methodological limitations, inconsistent findings, and lack of evidence from LMIC imply an urgent need for further investigations. The potential for broader utilization of SNA among providers remains largely untapped and the findings of this review may contain important value for building optimal healthcare delivery networks. PROSPERO REGISTRATION NUMBER: The protocol was published and registered with PROSPERO, the International Prospective Register of Systematic Reviews (CRD42020205996).

The impact of global budget on expenditure, service volume, and quality of care among patients with pneumonia in a secondary hospital in China: a retrospective study.

BACKGROUND: The Chinese government has begun to dampen the growth of health expenditure by implementing Global Budgets (GB). Concerns were raised about whether reductions in expenditure would lead to a deterioration of quality of care. This paper aims to evaluate the impact of GB on health expenditure, service volume and quality of care among Chinese pneumonia patients. METHODS: A secondary hospital that replaced Fee-For-Service (FFS) with GB in China in 2016 was sampled. We used daily expenditure to assess health expenditure; monthly admission, length of stay (LOS), number of drugs per record and record containing antibiotics to evaluate service volume; record with multiple antibiotics and readmission to assess quality of care. Descriptive analyses were adopted to evaluate changes after the reform, logistic regression and multivariable linear regressions were used to analyze changes associated with the reform. RESULTS: In 2015 and 2016, 3400 admissions from 3173 inpatients and 2342 admissions from 2246 inpatients were admitted, respectively. According to regression analyses, daily expenditure, LOS, readmission, and records with multiple antibiotic usages significantly declined after the reform. However, no significant relation was observed between GB and the number of drugs per record or record containing antibiotics. CONCLUSIONS: When compared with FFS, GB can curtail health expenditure and improve quality of care. As far as service volume was concerned, LOS and monthly admission declined, while number of drugs per record and record containing antibiotics were not affected.

A survey of availability, price and affordability of essential medicines from 2011 to 2016 in Chinese secondary and tertiary hospitals.

BACKGROUND: Essential medicines are those drugs that satisfy the priority health care needs of the population and help with functioning healthcare systems. Although many countries have formulated an essential medicine list, almost half of the global population still lack regular access to essential medicines. Research about the initiation of National Essential Medicines Policy in Chinese secondary and tertiary hospitals is inadequate, and the long-term effect on access after the reform is still unknown. This study's objective was to investigate the access to essential medicines in mainland China's secondary and tertiary hospitals. METHODS: Data on the access to 30 essential medicines from China's National Essential Medicine List were obtained from China Medicine Economic Information database covering 396 secondary hospitals and 763 tertiary hospitals. We improved the standard methodology developed by the World Health Organization and the Health Action International to measure the availability, median price ratio (MPR) and the incidence of catastrophic drug expenditure (CDE). RESULTS: Five essential medicines had > 50% availability and the nationwide availability kept steady; availability of drugs in eastern regions of China was significantly higher than the central and western regions. The median MPR of 30 drugs nationwide kept steady approximately 5; MPR of drugs in the eastern regions was significantly higher than the central and western regions and the ratio of MPR of innovator brands to generics increased from 3.66 to 6.32 during the study period. The incidence of CDE caused by essential medicines decreased from 2011 to 2014; brand name medicines were more likely to cause CDE than generics and rural patients have a greater tendency to fall into CDE. CONCLUSIONS: After the implementation of National Essential Medicines Policy, the MPR of essential medicines was well controlled and became more affordable in the context of steady availability. This has highlighted the problems associated with region disparity and inequity between rural and urban areas in the delivery of essential medicines and sustainable mechanisms are needed to deepen the National Essential Medicines Policy in mainland China.

Effectiveness of hierarchical medical system policy: an interrupted time series analysis of a pilot scheme in China.

The Chinese healthcare system faces a dilemma between its hospital-centric approach to healthcare delivery and a rapidly ageing population that requires strong primary care. To improve system efficiency and continuity of care, the Hierarchical Medical System (HMS) policy package was issued in November 2014 and fully implemented in 2015 in Ningbo, Zhejiang province, China. This study aimed to investigate the impact of the HMS on the local healthcare system. We conducted a repeated cross-sectional study with quarterly data collected between 2010 and 2018 from Yinzhou district, Ningbo. The data were analysed with an interrupted time series design to assess the impact of HMS on the changes in levels and trends of three outcome variables: primary care physicians' (PCPs') patient encounter ratio (i.e. the mean quarterly number of patient encounters of PCPs divided by that of all other physicians), PCP degree ratio (i.e. the mean degree of PCPs divided by the mean degree of all other physicians, with the mean degree revealing the mean activity and popularity of physicians, which reflected the extent to which he/she coordinated with others in delivering health services), and PCP betweenness centrality ratio (i.e. the mean betweenness centrality of PCPs divided by the mean betweenness centrality of all other physicians; the mean betweenness centrality was interpreted as the mean relative importance of physicians within the network, indicating the centrality of the network). Observed results were compared with counterfactual scenarios computed based on pre-HMS trends. Between January 2010 and December 2018, 272 267 patients visited doctors for hypertension, a representative non-communicable disease with a high prevalence of 44.7% among adults aged 35-75 years, amounting to a total of 9 270 974 patient encounters. We analysed quarterly data of 45 464 observations over 36 time points. Compared to the counterfactual, by the fourth quarter of 2018, the PCP patient encounter ratio rose by 42.7% [95% confidence interval (CI): 27.1-58.2, P < 0.001], the PCP degree ratio increased by 23.6% (95%CI: 8.6-38.5, P < 0.01) and the PCP betweenness centrality ratio grew by 129.4% (95%CI: 87.1-171.7, P < 0.001). The HMS policy can incentivize patients to visit primary care facilities and enhance the centrality of PCPs within their professional network.

lncRNA ZFAS1 promotes the ox-LDL induced proliferation, invasion and migration of vascular smooth muscle cells.

Atherosclerosis is a chronic progressive inflammatory vascular disease. The dysfunction of vascular smooth muscle cells (VSMCs) induced by oxidized low-density lipoprotein (ox-LDL) contributes to the formation of atherosclerotic lesions. Additionally, upregulation of the long non-coding RNA zinc finger antisense 1 (ZFAS1) was observed in the plaques of patients with atherosclerosis. The aim of the present study was to explore the functional role of ZFAS1 in atherosclerosis progression. Reverse transcription-quantitative PCR was performed to analyze ZFAS1 mRNA expression, and western blotting was performed to determine the protein expression levels of Ki67, proliferating cell nuclear antigen (PCNA), matrix metallopeptidase (MMP)2 and MMP9. The Cell Counting Kit-8 assay was used to test cell viability. Finally, wound healing and Transwell chamber assays were performed to evaluate cell migration and invasion, respectively. The current findings demonstrated that ZFAS1 expression was upregulated by ox-LDL stimulation in VSMCs. Moreover, ZFAS1 overexpression promoted the ox-LDL-induced proliferation, migration and invasion of VSMCs, and upregulated the expression levels of proteins associated with cellular proliferation (Ki67 and PCNA), migration and invasion (MMP2 and 9). By contrast, ZFAS1-knockdown inhibited the proliferation, migration and invasion of VSMCs, and suppressed cell proliferation-, migration- and invasion-associated protein expression. In conclusion, ZFAS1 promoted the ox-LDL-induced proliferation, invasion and migration of VSMCs. Thus, ZFAS1 may represent a novel biomarker for dysfunction of VSMCs in the pathological condition of atherosclerosis.

Physician patient-sharing relationships and healthcare costs and utilization in China: social network analysis based on health insurance data.

OBJECTIVES: Evidence on physician patient-sharing relationships from developing countries is limited. This study aimed to identify patient-sharing networks among physicians in China and explore the effect of attributes of physician networks on healthcare utilization and costs. METHODS: Retrospective analysis was undertaken based on healthcare claims from Urban Employee Basic Medical Insurance Data spanning the years 2015 to 2018. We identified patients with hypertension and modeled physician patient-sharing networks using social network analysis. Relationships among physicians were further quantified using network measures. We fitted a log-linear model to examine the association between networks and healthcare at the physician level. RESULTS: 29,321 patients, seen by 3,429 physicians from 57 hospitals in one eastern city of China were included. Physicians were connected to 21 other physicians (threshold = 1 shared patients) or 7 other physicians (threshold = 4, 6, or 8 shared patients). Degree and centrality measures of physicians at primary care facilities were significantly lower than those at secondary or tertiary hospitals (p < 0.001). The links between physicians at different hospital grades were weak and patients tended to flow among physicians at the same hospital grade. Compared with a low closeness centrality, a medium level was associated with fewer hospitalization costs and days, and high closeness centrality was accompanied by a sharper decrease (all P < 0.001). CONCLUSIONS: Primary care physicians were located in peripheral positions in China, and the links between primary care facilities and higher-grade hospitals were still weak. Characteristics of physicians' networks and the position of physicians in the network were associated with spending and utilization of services, but not all associations were in the same direction.

Prevention of Diabetes in Overweight/Obese Adults through Traditional Chinese Patent Medicine: Study Protocol for a Prospective Cohort Study.

Background. Early intervention in prediabetes can prevent or delay the incidence of type 2 diabetes mellitus (T2DM). Traditional Chinese patent medicine (TCPM) is widely used in China to prevent T2DM. This study aims to evaluate the efficacy and safety of TCPMs for preventing T2DM. Method/Design. This study is a multicenter, cohort study with two arms. A total of 600 participants will be recruited. The participants will be divided into either intervention or control groups according to their own desire, and the exposure factor is the application of TCPMs. All participants will be encouraged to lead a healthy lifestyle, and the intervention group also used TCPMs based on syndrome differentiation. Incident diabetes and normalization of blood glucose are indexes of end point. Safety assessments and adverse event monitoring will also be conducted. The treatment duration is set for 24 weeks, and we will follow-up for another 2 years. Discussion. This trial may provide initial evidence regarding the efficacy and safety of TCPMs plus lifestyle intervention (LI) compared to LI alone for preventing T2DM and provide a comprehensive intervention plans that choose suitable TCPMs for diabetes prevention according to syndrome differentiation. Trial Registration Number. Chinese Clinical Trial Registry ID: ChiCTR1900023541, registered on 1 Jun 2019. The version identifier is 2018121702.

[Expressions of MMP-2 and COX-2 mRNA in bladder transitional cell carcinoma and their correlation].

OBJECTIVE: To determine the levels of MMP-2 and COX-2 mRNA in bladder transitional cell carcinoma tissues and explore their relationship. METHODS: We enrolled in this study 42 patients with bladder transitional cell carcinoma, including Ta-T1 (n = 18), T2-T4 (n = 24), G1 (n = 12), G2 (n = 19), G3 (n = 11), metastasis (n =26) and non-metastasis (n = 16). Another 5 cases of normal bladder tissues were taken as controls, and the levels of MMP-2 and COX-2 mRNA were detected by RT-PCR. RESULTS: The relative expressions of COX-2 mRNA were 1.038 +/- 0. 484 in Ta-T1, 1.489 +/- 0.584 in T2-T4, 0.920 +/- 0.442 in G1, 1.338 +/- 0.584 in G2 and 1.632 +/- 0.515 in G3, all significantly higher than that of the controls (0.460 +/- 0.224, P < 0.05). And the corresponding relative levels of MMP-2 mRNA were 1.107 +/- 0.384, 1.604 +/- 0.425, 0.971 +/- 0.370, 1.445 +/- 0.378 and 1.755 +/- 0.387, also significantly higher than that of the latter group (0.423 +/- 0.227, P < 0.05). The COX-2 and MMP-2 mRNA levels in the tumor tissues with and without metastasis were 1.591 +/- 0.455 vs 0.815 +/- 0.430 and 1.676 +/- 0.339 vs 0.927 +/- 0.228, (P < 0.01), respectively, with a positive correlation between the mRNA level of COX-2 and that of MMP-2 (r = 0. 703, P < 0.01). CONCLUSION: MMP-2 and COX-2 mRNA are highly expressed in bladder transitional cell carcinoma tissues and their expressions are positively correlated with the degree of malignancy. MMP-2 and COX-2 might play a synergetic role in the pathogenesis and progression of bladder transitional cell carcinoma.