Spin-Charge Separation and Kinetic Energy in the t-J Model

I show that spin-charge separation in 2-D t-J model leads to an increase of kinetic energy. Using a sum rule, I derive an exact expression for the lowest possible KE (E_{bound}) for any state without doubly occupied sites. KE of relevant slave-boson and Schwinger-boson mean-field states -- which exhibit complete spin-charge separation -- are found to be much larger than E_{bound}. Examination of n(k) shows that the large increse in KE is due to excessive depletion of electrons from the bottom of the band (Schwinger boson) and of holes from the top (slave boson). To see whether the excess KE is simply due to poor treatment of the constraints, I solve the constraint problem analytically for the Schwinger boson case in the J = 0 limit. This restores gauge invariance, incorrectly violated in MF theories. The result is a generalized Hartree-Fock state of the Hubbard model, but one that includes spin waves. Even after constraints are imposed correctly, the KE remains much larger than E_{bound}. These results support the notion, advanced earlier [PRB 61, 8663 (2000)] that spin-charge separation in the MF state costs excessive KE, and makes the state unstable toward recombination processes which lead to superconductivity in d = 2 and a Fermi liquid state in higher dimensions.Comment: 13 pages, LateX plus three figures. To appear in Phys Rev B Typos correcte

Collinear N\'eel-type ordering in partially frustrated lattices

We consider two partially frustrated S = 1/2 antiferromagnetic spin systems on the triangular and pentagonal lattices. In an elementary plaquette of the two lattices, one bond has exchange interaction strength $\alpha$ ($\alpha \leq 1$) whereas all other bonds have exchange interaction strength unity. We show that for $\alpha$ less than a critical value $\alpha_{c}$, collinear N\'eel-type ordering is possible in the ground state. The ground state energy and the excitation spectrum have been determined using linear spin wave theory based on the Holstein-Primakoff transformation.Comment: Four pages, LaTeX, Four postscripts figures, Phys. Rev. B58, 73 (1998

Intake of New Zealand blackcurrant powder affects skin-borne volatile organic compounds in middle-aged and older adults

Skin volatile organic compounds (VOCs) can cause body odor or reveal human disease and may result from lipid peroxidation or activity by skin bacteria. We examined the effect of intake of New Zealand blackcurrant (NZBC) powder for 77 skin VOCs in middle-aged and older adults in a cross-over design. Fourteen adults (9 males, age: 55±5 yr) consumed NZBC powder for 7 days (6 g·day-1 with 138.6 mg anthocyanins). Two hours after the last intake, a passive flux sampler with trapping media was applied in the base of the neck for one hour. Gas chromatography-mass spectrometry was used for media analysis. Habitual anthocyanin intake was quantified using a food frequency questionnaire. Compared to control (i.e. no intake of NZBC powder), emission of six skin VOCs, i.e. 2-nonenal, acetic acid, 2-hexanone, 6-methyl-5-hepten-2-one, benzaldehyde, allyl methyl sulphide, were lower by more than 25%. Increases were observed for γ-octanolactone (+184%) and γ-decanolactone (+89%). A trend for decrease was observed for isovaleraldehyde, hexanal and 2-pentanone and an increase for heptanoic acid and γ-nonanolactone. There was a significant correlation with daily habitual dietary anthocyanin intake for control values of hexanal and percentage change of γ-octanolactone. NZBC powder can change emanation of some VOCs in human skin. Analysis of skin VOCs following specific polyphenol intake may address the impact of dietary components to affect internal metabolic processes, body odor and health

11^{11}B NMR study of pure and lightly carbon doped MgB2_2 superconductors

We report a $^{11}$B NMR line shape and spin-lattice relaxation rate ($1/(T_1T)$) study of pure and lightly carbon doped MgB$_{2-x}$C$_{x}$ for $x=0$, 0.02, and 0.04, in the vortex state and in magnetic field of 23.5 kOe. We show that while pure MgB$_2$ exhibits the magnetic field distribution from superposition of the normal and the Abrikosov state, slight replacement of boron with carbon unveils the magnetic field distribution of the pure Abrikosov state. This indicates a considerable increase of $H_{c2}^c$ with carbon doping with respect to pure MgB$_2$. The spin-lattice relaxation rate $1/(T_1T)$ demonstrates clearly the presence of a coherence peak right below $T_c$ in pure MgB$_2$, followed by a typical BCS decrease on cooling. However, at temperatures lower than $\approx 10$K strong deviation from the BCS behavior is observed, probably from residual contribution of the vortex dynamics. In the carbon doped systems both the coherence peak and the BCS temperature dependence of $1/(T_1T)$ weaken, an effect attributed to the gradual shrinking of the $\sigma$ hole cylinders of the Fermi surface with electron doping.Comment: 8 pages, 6 figures, submitted to Phys. Rev.

Current distribution of Achatina fulica, in the State of São Paulo including records of Aelurostrongylus abstrusus (Nematoda) larvae infestation

The currently known distribution range of Achatina fulica Bowdich, 1822, in the state of São Paulo, Brazil, is presented. The record of A. fulica naturally infested with Aelurostrongylus abstrusus larvae (Railliet, 1898) (Nematoda: Metastrongylidae) can be found in the city of Guaratinguetá. It was found A. fulica with Metastrongylidae larvae without known medical and veterinary importance in the cities of Carapicuíba, Embu-Guaçu, Itapevi, São Caetano do Sul, São Paulo and Taboão da Serra.É apresentada a distribuição de Achatina fulica Bowdich, 1822 no Estado de São Paulo, Brasil. É fornecido o registro de A. fulica naturalmente infestada por larvas de Aelurostrongylus abstrusus (Railliet, 1898) (Nematoda: Metastrongylidae) no município de Guaratinguetá. Foi encontrada A. fulica portando larvas de Metastrongylidae sem importância médica e veterinária conhecida nos municípios de Carapicuíba, Embu Guaçu, Itapevi, São Caetano do Sul, São Paulo e Taboão da Serra

Clinical significance in the number of involved lymph nodes in patients that underwent surgery for pathological stage III-N2 non-small cell lung cancer

<p>Abstract</p> <p>Purpose</p> <p>This study investigated whether the number of involved lymph nodes is associated with the prognosis in patients that underwent surgery for pathological stage (p-stage) III/N2 NSCLC.</p> <p>Subjects</p> <p>This study evaluated 121 patients with p-stage III/N2 NSCLC.</p> <p>Results</p> <p>The histological types included 65 adenocarcinomas, 39 squamous cell carcinomas and 17 others. The average number of dissected lymph nodes was 23.8 (range: 6-55). The average number of involved lymph nodes was 5.9 (range: 1-23). The 5-year survival rate of the patients was 51.0% for single lymph node positive, 58.9% for 2 lymph nodes positive, 34.2% for 3 lymph nodes positive, and 30.0% for 4 lymph nodes positive, and 20.4% for more than 5 lymph nodes positive. The patients with either single or 2 lymph nodes positive had a significantly more favorable prognosis than the patients with more than 5 lymph nodes positive. A multivariate analysis revealed that the number of involved lymph nodes was a significant independent prognostic factor.</p> <p>Conclusion</p> <p>Surgery appears to be preferable as a one arm of multimodality therapy in p-stage III/N2 patients with single or 2 involved lymph nodes. The optimal incorporation of surgery into the multimodality approach therefore requires further clinical investigation.</p

Validation of two automatic devices for the self-measurement of blood pressure according to the ANSI/AAMI/ISO81060-2:2009 guidelines: the Omron BP765 (HEM-7311-ZSA) and the Omron BP760N (HEM-7320-Z)

Hakuo Takahashi, Masamichi Yoshika, Toyohiko Yokoi Department of Clinical Sciences and Laboratory Medicine, Kansai Medical University, Hirakata Osaka, Japan Background: Allowing patients to measure their blood pressure (BP) at home will be the standard for evaluating the disease state as the process of clinical diagnosis, and it is recognized as having great clinical utility. To measure BP as accurately as possible, innovative techniques have been incorporated into home BP measurement devices. Objective: The present study aimed to evaluate the performance of the Omron BP765 (HEM-7311-ZSA) and the Omron BP760N (HEM-7320-Z), which are equipped with functions to detect irregular pulses and arm movement that lead to inaccurate BP readings. Methods: A team of three trained medical doctors validated the performance of these devices by comparing the data alternatively obtained from both devices with those from a standard mercury sphygmomanometer. Results: The magnitude of the difference in BP readings between the tested device and the standard mercury sphygmomanometer in the Omron BP765 and BP760N was within the range of &plusmn;3 mmHg (mean) allowed by the American National Standards Institute, Inc/Association for the Advancement of Medical Instrumentation/International Organization for Standardization (ANSI/AAMI/ISO) 81060-2:2009 guidelines. Conclusion: The Omron BP765 and BP760N were found useful for the self-measurement of BP at home, and their performance fulfilled the requirement of the ANSI/AAMI/ISO 81060-2:2009 guidelines. Keywords: blood pressure, self-measurement, device, validation, ANSI/AAMI/ISO 81060-2:200

Validation of Omron RS8, RS6, and RS3 home blood pressure monitoring devices, in accordance with the European Society of Hypertension International Protocol revision 2010

Hakuo Takahashi, Masamichi Yoshika, Toyohiko YokoiDepartment of Clinical Sciences and Laboratory Medicine, Kansai Medical University, Hirakata, Osaka, JapanBackground: Allowing patients to measure their blood pressure at home is recognized as being of clinical value. However, it is not known how often these measurements are taken correctly. Blood pressure monitors for home use fall into two types based on the position of the cuff, ie, at the upper arm or the wrist. The latter is particularly convenient, as measurements can be taken fully clothed. This study aimed to evaluate the performance of the wrist-type blood pressure monitors Omron RS8 (HEM-6310F-E), Omron RS6 (HEM-6221-E), and Omron RS3 (HEM-6130-E).Methods: A team of three trained doctors validated the performance of these devices by comparing the measurements obtained from these devices with those taken using a standard mercury sphygmomanometer. All the devices met the validation requirements of the European Society of Hypertension International Protocol revision 2010.Results: The difference in blood pressure readings between the tested device and the standard mercury sphygmomanometer was within 3 mmHg, which is acceptable according to the European Society of Hypertension guidelines.Conclusion: All the home devices tested were found to be suitable for measuring blood pressure at home because their performance fulfilled the requirement of the guidelines.Keywords: blood pressure, device, European Society of Hypertension, guideline, measurement, validatio

Pelecitus helicinus Railliet & Henry, 1910 (Filarioidea, Dirofilariinae) and other nematode parasites of Brazilian birds

We report Pelecitus helicinus Railliet & Henry, 1910 from 13 species of birds of 2 orders and 7 families, collected from the states of São Paulo and Mato Grosso, Brazil. All 13 constitute new host records for this nematode. In addition, we report the first record of Aprocta golvani Diaz-Ungria, 1963 from Brazil and Monasa nigrifrons (Bucconidae), as well as a number of other nematode records from Neotropical birds