The Impact of Change in Hospital Admissions When Primary Care Is Provided by a Single Primary Care Physician: A Cohort Study Among HMO Patients in Israel.

OBJECTIVES: An Israeli health maintenance organization (HMO) changed its policy from freedom of choice in choosing any primary care physician (PCP) to provide health care to one provider allocated to the patients. We examined outcome measures before and after the intervention in the study population. DESIGN: During a 2.5-year period (from June 2013 to December 2015), continuity of care by PCPs was achieved by a single provider. The change was computed for each participant according to the most visited PCP in the last year. PARTICIPANTS: A total of 208,286 patients aged 20 and older fulfilled the inclusion criteria. MAIN OUTCOME MEASURES: Future likelihood of hospitalization, number of PCP visits, and medication use before and after the intervention. RESULTS: After controlling for demographics, high continuity of care before and after intervention was associated with a lower likelihood of hospitalization for any condition (adjusted odds ratio [OR] = 0.90; 95% confidence interval [CI], 0.85-0.95; p = 0.003). No significant change was recorded for number of ambulatory visits or medication use. CONCLUSIONS: Changing Leumit HMO policy to continuity of care with a single provider is associated with a decreased future likelihood of hospitalization. This suggests that policies that encourage patients to concentrate their care with a single provider may lead to lower hospitalization rates and possibly lower healthcare costs.

Does a policy that requires adherence to a regular primary care physician improve the actual adherence of patients?

BACKGROUND: Continuity of care by the same personal physician is a key factor in an effective and efficient health care system. Studies that support the association between high adherence and better outcomes were done in settings where allocation to the same physician was a long-term policy. OBJECTIVES: To evaluate the influence that changing organizational policy from the free choice of a primary care physician to a mandatory continuity of care by the same physician has on adherence to a personal physician. METHODS: A cross-sectional study based on electronic databases; comparison of adherence and demographic characteristics (sex, age, and socio-economic status) of 208,286 Leumit enrollees who met the inclusion criteria, according to change in the adherence to a personal physician. To evaluate adherence, we used the Usual Provider of Care (UPC) index, which measures the number of visits made to the personal doctor out of the total primary care physician visits over the same period. The patients were divided into groups according to their UPC level. RESULTS: The data shows that 54.5% of the patients were high adherers even before the organizational change; these rates are similar to those published by various organizations worldwide, years after mandating continuity of care by the same physician. In the year following the intervention, only 34.5% of the patients changed the level of their adherence group. Of these, 64% made a shift to a higher adherence group. Before the intervention, the high adherers were older (mean age 57.8 vs. 49.3 years in the low adherers group) and from a higher SES (mean SES status 9.32 vs. 8.71). After the intervention, a higher proportion of older patients and patients from a higher SES changed their adherence to a higher group. Sex distribution was similar over all the adherence level groups and did not change after the intervention. CONCLUSIONS AND POLICY IMPLICATIONS: A policy change that encouraged adherence to an allocated primary care physician managed to improve adherence only in specific groups. Health organizations need to examine the potential for change and the groups they want to influence and direct their investment wisely. TRIAL REGISTRATION: retrospectively registered.

Observation of chiral surface excitons in a topological insulator Bi2Se3.

The protected electron states at the boundaries or on the surfaces of topological insulators (TIs) have been the subject of intense theoretical and experimental investigations. Such states are enforced by very strong spin-orbit interaction in solids composed of heavy elements. Here, we study the composite particles-chiral excitons-formed by the Coulomb attraction between electrons and holes residing on the surface of an archetypical 3D TI, [Formula: see text] Photoluminescence (PL) emission arising due to recombination of excitons in conventional semiconductors is usually unpolarized because of scattering by phonons and other degrees of freedom during exciton thermalization. On the contrary, we observe almost perfectly polarization-preserving PL emission from chiral excitons. We demonstrate that the chiral excitons can be optically oriented with circularly polarized light in a broad range of excitation energies, even when the latter deviate from the (apparent) optical band gap by hundreds of millielectronvolts, and that the orientation remains preserved even at room temperature. Based on the dependences of the PL spectra on the energy and polarization of incident photons, we propose that chiral excitons are made from massive holes and massless (Dirac) electrons, both with chiral spin textures enforced by strong spin-orbit coupling. A theoretical model based on this proposal describes quantitatively the experimental observations. The optical orientation of composite particles, the chiral excitons, emerges as a general result of strong spin-orbit coupling in a 2D electron system. Our findings can potentially expand applications of TIs in photonics and optoelectronics.

Chiral Spin Mode on the Surface of a Topological Insulator.

Using polarization-resolved resonant Raman spectroscopy, we explore collective spin excitations of the chiral surface states in a three dimensional topological insulator, Bi_{2}Se_{3}. We observe a sharp peak at 150 meV in the pseudovector A_{2} symmetry channel of the Raman spectra. By comparing the data with calculations, we identify this peak as the transverse collective spin mode of surface Dirac fermions. This mode, unlike a Dirac plasmon or a surface plasmon in the charge sector of excitations, is analogous to a spin wave in a partially polarized Fermi liquid, with spin-orbit coupling playing the role of an effective magnetic field.

Analogy Between the "Hidden Order" and the Orbital Antiferromagnetism in URu_{2-x}Fe_{x}Si_{2}.

We study URu_{2-x}Fe_{x}Si_{2}, in which two types of staggered phases compete at low temperature as the iron concentration x is varied: the nonmagnetic "hidden order" (HO) phase below the critical concentration x_{c}, and unconventional antiferromagnetic (AFM) phase above x_{c}. By using polarization resolved Raman spectroscopy, we detect a collective mode of pseudovectorlike A_{2g} symmetry whose energy continuously evolves with increasing x; it monotonically decreases in the HO phase until it vanishes at x=x_{c}, and then reappears with increasing energy in the AFM phase. The mode's evolution provides direct evidence for a unified order parameter for both nonmagnetic and magnetic phases arising from the orbital degrees-of-freedom of the uranium-5f electrons.

Discovery of an Unconventional Charge Density Wave at the Surface of K_{0.9}Mo_{6}O_{17}.

We use angle resolved photoemission spectroscopy, Raman spectroscopy, low energy electron diffraction, and x-ray scattering to reveal an unusual electronically mediated charge density wave (CDW) in K_{0.9}Mo_{6}O_{17}. Not only does K_{0.9}Mo_{6}O_{17} lack signatures of electron-phonon coupling, but it also hosts an extraordinary surface CDW, with T_{S_CDW}=220 K nearly twice that of the bulk CDW, T_{B_CDW}=115 K. While the bulk CDW has a BCS-like gap of 12 meV, the surface gap is 10 times larger and well in the strong coupling regime. Strong coupling behavior combined with the absence of signatures of strong electron-phonon coupling indicates that the CDW is likely mediated by electronic interactions enhanced by low dimensionality.

Heavy fermions. Chirality density wave of the "hidden order" phase in URu2Si2.

A second-order phase transition in a physical system is associated with the emergence of an "order parameter" and a spontaneous symmetry breaking. The heavy fermion superconductor URu2Si2 has a "hidden order" (HO) phase below the temperature of 17.5 kelvin; the symmetry of the associated order parameter has remained ambiguous. Here we use polarization-resolved Raman spectroscopy to specify the symmetry of the low-energy excitations above and below the HO transition. We determine that the HO parameter breaks local vertical and diagonal reflection symmetries at the uranium sites, resulting in crystal field states with distinct chiral properties, which order to a commensurate chirality density wave ground state.

Phonon energy gaps in the charged incommensurate planes of the spin-ladder Sr14Cu24O41 compound by Raman and infrared spectroscopy.

The terahertz (THz) excitations in the quantum spin-ladder system Sr14Cu24O41 have been determined along the c axis using THz time-domain, Raman, and infrared spectroscopy. Low-frequency infrared and Raman active modes are observed above and below the charge-ordering temperature T(co) is approximately equal to 200 K over a narrow interval approximately equal to 1-2 meV approximately equal to 8-16 cm(-1)). A new infrared mode at approximately equal to 1 meV develops below approximately equal to 100 K. The temperature dependence of these modes shows that they are coupled to the charge- and spin-density-wave correlations in this system. These low-energy features are conjectured to originate in the gapped sliding motion of the chain and ladder subsystems, which are both incommensurate and charged.

Anisotropies in the optical ac and dc conductivities in lightly doped La(2 - x)Sr(x)CuO4: the role of deep and shallow acceptor states.

We investigate the origin of the optical ac and dc conductivity anisotropies observed in the low temperature orthorhombic phase of lightly doped, untwinned La(2 - x)Sr(x)NiO(4) single crystals. We show that these anisotropies can be naturally ascribed to the emergence of two odd parity, rotational-symmetry-broken, localized impurity acceptor states, one deeper and one shallower, resulting from the trapping of doped holes by the Coulomb potential provided by the Sr ions. These two lowest-energy, p-wave-like states are split by orthorhombicity and are partially filled with holes. This leaves a unique imprint in the optical ac conductivity, which shows two distinct far-infrared continuum absorption energies corresponding to the photoionization of the deep and shallow acceptor states. Furthermore, we argue that the existence of two independent and orthogonal channels for hopping conductivity, directly associated with the two orthorhombic directions, also quantitatively explains the observed low temperature anisotropies in the dc conductivity.

Theory of multiband superconductivity in spin-density-wave metals.

We study the emergence of multiband superconductivity with s- and d-wave symmetry on the background of a spin density wave (SDW). We show that the SDW coherence factors renormalize the momentum dependence of the superconducting (SC) gap, yielding a SC state with an unconventional s-wave symmetry. Interband Cooper pair scattering stabilizes superconductivity in both symmetries. With increasing SDW order, the s-wave state is more strongly suppressed than the d-wave state. Our results are universally applicable to two-dimensional systems with a commensurate SDW.

Observation of a 500 meV collective mode in La2-xSrxCuO4 and Nd2CuO4 using resonant inelastic X-ray scattering.

Utilizing resonant inelastic x-ray scattering, we report a previously unobserved mode in the excitation spectrum of La2-xSrxCuO4 and Nd2CuO4 at 500 meV. The mode is peaked around the (pi, 0) point in reciprocal space and is observed to soften, and broaden, away from this point. Samples with x=0, 0.01, 0.05, and 0.17 were studied. The new mode is found to be rapidly suppressed with increasing Sr content and is absent at x=0.17, where it is replaced by a continuum of excitations. This mode is only observed when the incident x-ray polarization is normal to the CuO planes.

Observation of Leggett's collective mode in a multiband MgB2 superconductor.

We report observation of Leggett's collective mode in a multiband MgB2 superconductor with Tc=39 K arising from the fluctuations in the relative phase between two superconducting condensates. The novel mode is observed by Raman spectroscopy at 9.4 meV in the fully symmetric scattering channel. The observed mode frequency is consistent with theoretical considerations based on first-principles computations.

Quantum melting of the hole crystal in the spin ladder of Sr(14-x)CaxCu24O41.

We have used resonant soft x-ray scattering to study the effects of discommensuration on the hole Wigner crystal (HC) in the spin ladder Sr(14-x)CaxCu24O41 (SCCO). As the hole density is varied the HC forms only with the commensurate wave vectors L(L) = 1/5 and L(L) = 1/3; for incommensurate values it "melts." A simple scaling between L(L) and temperature is observed, tau1/3/tau1/5 = 5/3, indicating an inverse relationship between the interaction strength and wavelength. Our results suggest that SCCO contains hole pairs that are crystallized through an interplay between lattice commensuration and Coulomb repulsion, reminiscent of the "pair density wave" scenario.

Crystallization of charge holes in the spin ladder of Sr14Cu24O41.

Determining the nature of the electronic phases that compete with superconductivity in high-transition-temperature (high-T(c)) superconductors is one of the deepest problems in condensed matter physics. One candidate is the 'stripe' phase, in which the charge carriers (holes) condense into rivers of charge that separate regions of antiferromagnetism. A related but lesser known system is the 'spin ladder', which consists of two coupled chains of magnetic ions forming an array of rungs. A doped ladder can be thought of as a high-T(c) material with lower dimensionality, and has been predicted to exhibit both superconductivity and an insulating 'hole crystal' phase in which the carriers are localized through many-body interactions. The competition between the two resembles that believed to operate between stripes and superconductivity in high-T(c) materials. Here we report the existence of a hole crystal in the doped spin ladder of Sr14Cu24O41 using a resonant X-ray scattering technique. This phase exists without a detectable distortion in the structural lattice, indicating that it arises from many-body electronic effects. Our measurements confirm theoretical predictions, and support the picture that proximity to charge ordered states is a general property of superconductivity in copper oxides.

Magnetic order in lightly doped La2-xSrxCuO4.

We study long wavelength magnetic excitations in lightly doped La2-xSrxCuO4 (x

Collective density-wave excitations in two-leg Sr14-xCaxCu24O41 ladders.

Raman measurements in the 1.5-20 cm(-1) energy range were performed on single crystals of Sr14-xCaxCu24O41. A quasielastic scattering peak (QEP) which softens with cooling is observed only in the polarization parallel to the ladder direction for samples with x=0, 8, and 12. The QEP is a Raman fingerprint of pinned collective density wave excitations screened by uncondensed carriers in the ladder structures. Our results suggest that transport in metallic samples, which is similar to transport in underdoped high-T(c) cuprates, is driven by a collective electronic response.

Attitudes of mothers toward their daughters' use of contraceptives in Israel.

The objective of the study was to examine mothers' knowledge about contraception, their attitudes to their daughters' use of contraception, and their communication with their daughters on the subject. A 20-item questionnaire was distributed in gynecological clinics throughout Israel for completion by women who had daughters over the age of 14 years. The questionnaire covered the mothers' demographic data, use of contraception, knowledge of contraception, attitude to their daughters' contraceptive use and sexual relationships, and communication with their daughters about contraception. Only 36% of the women received contraceptive information from physicians. Almost half felt their daughter should begin sexual relations when she felt she was ready; over two-thirds felt she should begin using contraception before or at the time of beginning sexual relations. Over three-quarters spoke with their daughters about contraception. Higher educational level of the mother was associated with high rate use of contraception by the mother, her support of earlier use of contraception by her daughter, a greater likelihood of her discussing contraception with her daughter, and a lesser likelihood to view contraceptives as dangerous to one's health. It is concluded that mothers of teenage daughters in Israel are involved in their daughters' decisions to begin sexual relations and the use of contraceptives. Their knowledge of contraception is adequate, although some gaps are still apparent. Clear correlation is found between higher educational level of the mothers and a more liberal attitude toward their daughters' sex life.

Sliding density wave in Sr14Cu24O41 ladder compounds.

We used transport and Raman scattering measurements to identify the insulating state of self-doped spin (1/2) two-leg ladders of Sr14Cu24O41 as a weakly pinned, sliding density wave with nonlinear conductivity and a giant dielectric response that persists to remarkably high temperatures.

Nonmonotonic d(x(2)-y(2)) superconducting order parameter in Nd2-xCexCuO4.

Low energy polarized electronic Raman scattering of the electron-doped superconductor Nd2-x Ce x CuO4 ( x = 0.15, T(c) = 22 K) has revealed a nonmonotonic d(x(2)-y(2)) superconducting order parameter. It has a maximum gap of 4.4k(B)T(c) at Fermi surface intersections with an antiferromagnetic Brillouin zone (the "hot spots") and a smaller gap of 3.3k(B)T(c) at fermionic Brillouin zone boundaries. The gap enhancement in the vicinity of the hot spots emphasizes the role of antiferromagnetic fluctuations and the similarity in the origin of superconductivity for electron- and hole-doped cuprates.