On-chip cavity quantum phonodynamics with an acceptor qubit in silicon

We describe a chip-based, solid-state analogue of cavity-QED utilizing acoustic phonons instead of photons. We show how long-lived and tunable acceptor impurity states in silicon nanomechanical cavities can play the role of a matter non-linearity for coherent phonons just as, e.g., the Josephson qubit plays in circuit-QED. Both strong coupling (number of Rabi oscillations ~ 100) and strong dispersive coupling (0.1-2 MHz) regimes can be reached in cavities in the 1-20 GHz range, enabling the control of single phonons, phonon-phonon interactions, dispersive phonon readout of the acceptor qubit, and compatibility with other optomechanical components such as phonon-photon translators. We predict explicit experimental signatures of the acceptor-cavity system.Comment: 6 pages, 2 figures, PDFLaTeX. New version improves clarit

NeutroOrderedAlgebra: Applications to Semigroups

Starting with a partial order on a NeutroAlgebra, we get a NeutroStructure. The latter if it satisfies the conditions of NeutroOrder, it becomes a NeutroOrderedAlgebra. In this paper, we apply our new defined notion to semigroups by studying NeutroOrderedSemigroups. More precisely, we define some related terms like NeutrosOrderedSemigroup, NeutroOrderedIdeal, NeutroOrderedFilter, NeutroOrderedHomomorphism, etc., illustrate them via some examples, and study some of their properties

Komposisi Jenis Dan Potensi Ancaman Tumbuhan Asing Invasif Di Taman Nasional Gunung Halimun-salak, Jawa Barat [Species Composition and Threat Potential of Invasive Plants Species in Gunung Halimun-salak National Park, West Java]

A study on species composition and threat potential of invasive plant species was conducted in the Gunung Halimun-Salak National Park,Cidahu Resort, West Java. We developed two plots of different altitudes. The result showed that there were four invasive alien species possessing potential threat to the ecosystem and native species in the National Park, i.e. Piper aduncum (Piperaceae, with an Important Value of 20,70); Calliandra calothyrsus (Mimosaceae, IV = 9,11), Austroeupatorium inulaefolium (Asteraceae, IV = 18,77), and Clidemia hirta (Melastomataceae) as shrub. The threats of invasive plants happen in open forest area and could occur from the residential or public places

Valley Splitting Theory of SiGe/Si/SiGe Quantum Wells

We present an effective mass theory for SiGe/Si/SiGe quantum wells, with an emphasis on calculating the valley splitting. The theory introduces a valley coupling parameter, $v_v$, which encapsulates the physics of the quantum well interface. The new effective mass parameter is computed by means of a tight binding theory. The resulting formalism provides rather simple analytical results for several geometries of interest, including a finite square well, a quantum well in an electric field, and a modulation doped two-dimensional electron gas. Of particular importance is the problem of a quantum well in a magnetic field, grown on a miscut substrate. The latter may pose a numerical challenge for atomistic techniques like tight-binding, because of its two-dimensional nature. In the effective mass theory, however, the results are straightforward and analytical. We compare our effective mass results with those of the tight binding theory, obtaining excellent agreement.Comment: 13 pages, 7 figures. Version submitted to PR

Decoherence of electron spin qubits in Si-based quantum computers

Direct phonon spin-lattice relaxation of an electron qubit bound by a donor impurity or quantum dot in SiGe heterostructures is investigated. The aim is to evaluate the importance of decoherence from this mechanism in several important solid-state quantum computer designs operating at low temperatures. We calculate the relaxation rate $1/T_1$ as a function of [100] uniaxial strain, temperature, magnetic field, and silicon/germanium content for Si:P bound electrons. The quantum dot potential is much smoother, leading to smaller splittings of the valley degeneracies. We have estimated these splittings in order to obtain upper bounds for the relaxation rate. In general, we find that the relaxation rate is strongly decreased by uniaxial compressive strain in a SiGe-Si-SiGe quantum well, making this strain an important positive design feature. Ge in high concentrations (particularly over 85%) increases the rate, making Si-rich materials preferable. We conclude that SiGe bound electron qubits must meet certain conditions to minimize decoherence but that spin-phonon relaxation does not rule out the solid-state implementation of error-tolerant quantum computing.Comment: 8 figures. To appear in PRB-July 2002. Revisions include: some references added/corrected, several typos fixed, a few things clarified. Nothing dramati

Lactobacilli and bifidobacteria in the feces of schoolchildren of two different socioeconomic groups: children from a favela and children from a private school

OBJECTIVE: To determine the number of lactobacillus and bifidobacterium colonies in the feces of schoolchildren from two different socioeconomic levels. METHODS: We analyzed fecal samples of children aged 6 to 10 years without gastrointestinal symptoms or recent use of antimicrobials. The first group included 86 children living in a favela in the city of Osasco, state of São Paulo, southeastern Brazil. The second group included 36 children attending a private school in the same city. Body mass index (BMI) was used to assess nutritional status according to the reference values of the National Center for Health Statistics (NCHS). Specific anaerobic culture media were used for isolation of colonies for 48 and 72 hours at 37 °C. The number of colonies was determined using the plate-counting method. RESULTS: The mean lactobacillus (1.125 x 10(9) colony-forming units, CFU/g) and bifidobacterium (1.675 x 10(9) CFU/g) counts in the private school group were higher (p -1.0 SD (n = 57): 0.350 x 10(9) and 0.420 x 10(9) CFU/g, respectively. CONCLUSION: The microbiota of schoolchildren living in unfavorable environmental conditions shows lower numbers of fecal lactobacillus and bifidobacterium colonies, especially in children with lower BMI values.OBJETIVO: Determinar o número de colônias de lactobacilos e bifidobactérias nas fezes de crianças escolares, pertencentes a dois estratos socioeconômicos. MÉTODOS: Foram analisadas amostras de fezes de crianças com idade entre 6 e 10 anos sem sintomas gastrointestinais ou uso recente de antimicrobianos. O primeiro grupo foi constituído por 86 crianças, moradoras em uma favela localizada no município de Osasco (SP). O segundo grupo foi constituído por 36 crianças matriculadas em uma escola particular da mesma cidade. O estado nutricional foi avaliado usando o índice de massa corporal (IMC) de acordo com os valores de referência do National Center for Health Statistics (NCHS). O isolamento das colônias foi realizado em meios de cultura específicos em anaerobiose, durante 48 e 72 horas a 37 °C. A determinação do número foi feita pelo método da contagem em placa. RESULTADOS: A mediana de lactobacilos (1,125 x 10(9) unidades formadoras de colônia, UFC/g) e bifidobactérias (1,675 x 10(9) UFC/g) na escola particular foi superior (p -1,0 desvio padrão (n = 57): 0,350 x 10(9) e 0,420 x 10(9) UFC/g, respectivamente. CONCLUSÃO: A microbiota de crianças escolares que moram em condições ambientais desfavoráveis apresenta menor número de colônias de lactobacilos e bifidobactérias nas fezes, especialmente naquelas com menores valores do IMC.Universidade Federal de São Paulo (UNIFESP) Departamento de PediatriaUNIFESP Departamento de PediatriaCentro Universitário Fundação e Instituto de Educação de Osasco Departamento de Ciências da Saúde Instituto de Pesquisa UnolabUNIFIEO Departamento de Ciências da Saúde Instituto de Pesquisa UnolabUNIFIEO Departamento de PediatriaUNIFESP Departamento de Microbiologia, Imunologia e ParasitologiaUNIFESP, Depto. de PediatriaUNIFESP, Depto. de PediatriaUNIFESP, Depto. de Microbiologia, Imunologia e ParasitologiaSciEL

Time course of collagen peak in bile duct-ligated rats

<p>Abstract</p> <p>Background</p> <p>One of the most useful experimental fibrogenesis models is the "bile duct-ligated rats". Our aim was to investigate the quantitative hepatic collagen content by two different methods during the different stages of hepatic fibrosis in bile duct-ligated rats on a weekly basis. We questioned whether the 1-wk or 4-wk bile duct-ligated model is suitable in animal fibrogenesis trials.</p> <p>Methods</p> <p>Of the 53 male Wistar rats, 8 (Group 0) were used as a healthy control group. Bile duct ligation (BDL) had been performed in the rest. Bile duct-ligated rates were sacrificed 7 days later in group 1 (10 rats), 14 days later in group 2 (9 rats), 21 days later in group 3(9 rats) and 28 days later in group 4 (9 rats). Eight rats underwent sham-operation (Sham). Hepatic collagen measurements as well as serum levels of liver enzymes and function tests were all analysed.</p> <p>Results</p> <p>The peak level of collagen was observed biochemically and histomorphometricly at the end of third week (P < 0.001 and P < 0.05). Suprisingly, collagen levels had decreased with the course of time such as at the end of fourth week (P < 0.01 and P < 0.05).</p> <p>Conclusion</p> <p>We have shown that fibrosis in bile duct-ligated rats is transient, i.e. reverses spontaneously after 3 weeks. This contrasts any situation in patients where hepatic fibrosis is progressive and irreversible as countless studies performed by many investigators in the same animal model.</p