Orbital Symmetry and Electron Correlation in Na_{x}CoO_2

Measurements of polarization-dependent soft x-ray absorption reveal that the electronic states determining the low-energy excitations of Na$_{x}$CoO$_2$ have predominantly $a_{1g}$ symmetry with significant O $2p$ character. A large transfer of spectral weight observed in O $1s$ x-ray absorption provides spectral evidence for strong electron correlations in the layered cobaltates. Comparing Co $2p$ x-ray absorption with calculations based on a cluster model, we conclude that Na$_{x}$CoO$_2$ exhibits a charge-transfer electronic character rather than a Mott-Hubbard character

Functional Quantum Nodes for Entanglement Distribution over Scalable Quantum Networks

We demonstrate entanglement distribution between two remote quantum nodes located 3 meters apart. This distribution involves the asynchronous preparation of two pairs of atomic memories and the coherent mapping of stored atomic states into light fields in an effective state of near maximum polarization entanglement. Entanglement is verified by way of the measured violation of a Bell inequality, and can be used for communication protocols such as quantum cryptography. The demonstrated quantum nodes and channels can be used as segments of a quantum repeater, providing an essential tool for robust long-distance quantum communication.Comment: 10 pages, 7 figures. Text revised, additional information included in Appendix. Published online in Science Express, 5 April, 200

Towards experimental entanglement connection with atomic ensembles in the single excitation regime

We present a protocol for performing entanglement connection between pairs of atomic ensembles in the single excitation regime. Two pairs are prepared in an asynchronous fashion and then connected via a Bell measurement. The resulting state of the two remaining ensembles is mapped to photonic modes and a reduced density matrix is then reconstructed. Our observations confirm for the first time the creation of coherence between atomic systems that never interacted, a first step towards entanglement connection, a critical requirement for quantum networking and long distance quantum communications

Prevalence and Effectiveness of Laxative Use Among Elderly Residents in a Regional Hospital Affiliated Nursing Home in Hsinchu County

Background: Long-term care residents are susceptible to constipation and one-half to three quarter of older nursing home residents receive laxatives regularly. Objectives: The purpose of this study was to evaluate the factors related to abnormal bowel function and explore the effectiveness of laxative treatment among the elderly residents of a nursing home. Patients and Methods: A total of 110 residents older than 65 years old was enrolled in this study. The following variables were gathered: age, gender, body mass index (BMI), length of stay, daily fluid intake, type of food, functional level, cognitive ability, physical therapy status, somatic and psychiatric diseases, number of medications, and medication use. The use and dosage of laxatives were recorded by means of Anatomical Therapeutic Chemical (ATC) classification system. Normal bowel function was defined as defecation frequency from three defecations per day to three defecations per week and stool consistency score of three to five on Bristol Stool Form Scale. A comparison between groups with normal and abnormal bowel function was drawn. Results: Low BMI, increased fluid intake, liquid food intake, poor functional level, poor cognition, and a history of stroke were significantly associated with altered bowel function (P < 0.05). The most frequently used laxatives were glycerol, senna glycoside, and magnesium oxide. There were significant differences in laxative regimens between residents with normal and altered bowel function; those with altered bowel function tended to take more laxatives than those with normal bowel function. Conclusions: This study suggested that treatment of constipation in the nursing home was unsatisfactory. To improve treatment outcomes in those susceptible to altered bowel function, a coordinated approach with involvement of physicians, nursing staff, and other professionals including dieticians and pharmacists seems necessary

Unifying the Phase Diagrams of the Magnetic and Transport Properties of La_(2-x)Sr_xCuO_4, 0 < x < 0.05

An extensive experimental and theoretical effort has led to a largely complete mapping of the magnetic phase diagram of La_(2-x)Sr_xCuO_4, and a microscopic model of the spin textures produced in the x < 0.05 regime has been shown to be in agreement with this phase diagram. Here we use this same model to derive a theory of the impurity-dominated, low temperature transport. Then, we present an analysis of previously published data for two samples: x = 0.002 data from Chen et. al., and x = 0.04 data from Keimer et. al. We show that the transport mechanisms in the two systems are the same, even though they are on opposite sides of the observed insulator-to-metal transition. Our model of impurity effects on the impurity band conduction, variable-range hopping conduction, and coulomb gap conduction, is similar to that used to describe doped semiconductors. However, for La_(2-x)Sr_xCuO_4 we find that in addition to impurity-generated disorder effects, strong correlations are important and must be treated on a equal level with disorder. On the basis of this work we propose a phase diagram that is consistent with available magnetic and transport experiments, and which connects the undoped parent compound with the lowest x value for which La_(2-x)Sr_xCuO_4 is found to be superconducting, x about 0.06.Comment: 7 pages revtex with one .ps figur

Pole Assignment for a Vibrating System with Aerodynamic Effect

This paper deals with a pole assignment problem by single-input state feedback control arising from a one-dimensional vibrating system with aerodynamic effect. On the practical side, we derive explicit formulae for the required controlling force terms, which can reassign part of the spectrum to the desired values while leaving the remaining spectrum unchanged. On the mathematical side, unlike the classical Sturm–Liouville problem, our eigenvalue problem is associated with a cubic pencil with unbounded operators as coefficients and has many interesting new features, one of which is that a new controllability condition appears. This condition together with the known controllability condition in the quadratic case are necessary and sufficient. This sheds light on the adjustment of the model parameters. We also analyze the spectrum of the associated noncompact operator and in particular show that the discrete spectrums of controlled and uncontrolled systems lie outside a closed interval on the negative real axis