959 research outputs found
The Fully Frustrated Hypercubic Model is Glassy and Aging at Large
We discuss the behavior of the fully frustrated hypercubic cell in the
infinite dimensional mean-field limit. In the Ising case the system undergoes a
glass transition, well described by the random orthogonal model. Under the
glass temperature aging effects show clearly. In the case there is no sign
of a phase transition, and the system is always a paramagnet.Comment: Figures added in uufiles format, and epsf include
Spectroscopic survey of M--type asteroids
M-type asteroids, as defined in the Tholen taxonomy (Tholen, 1984), are
medium albedo bodies supposed to have a metallic composition and to be the
progenitors both of differentiated iron-nickel meteorites and enstatite
chondrites. We carried out a spectroscopic survey in the visible and near
infrared wavelength range (0.4-2.5 micron) of 30 asteroids chosen from the
population of asteroids initially classified as Tholen M -types, aiming to
investigate their surface composition. The data were obtained during several
observing runs during the years 2004-2007 at the TNG, NTT, and IRTF telescopes.
We computed the spectral slopes in several wavelength ranges for each observed
asteroid, and we searched for diagnostic spectral features. We confirm a large
variety of spectral behaviors for these objects as their spectra are extended
into the near-infrared, including the identification of weak absorption bands,
mainly of the 0.9 micron band tentatively attributed to orthopyroxene, and of
the 0.43 micron band that may be associated to chlorites and Mg-rich
serpentines or pyroxene minerals such us pigeonite or augite. A comparison with
previously published data indicates that the surfaces of several asteroids
belonging to the M-class may vary significantly. We attempt to constrain the
asteroid surface compositions of our sample by looking for meteorite spectral
analogues in the RELAB database and by modelling with geographical mixtures of
selected meteorites/minerals. We confirm that iron meteorites, pallasites, and
enstatite chondrites are the best matches to most objects in our sample, as
suggested for M-type asteroids. The presence of subtle absorption features on
several asteroids confirms that not all objects defined by the Tholen M-class
have a pure metallic composition.Comment: 10 figures, 6 tables; Icarus, in pres
Propagação vegetativa de frutĂferas de caroço por estacas herbĂĄceas em escala comercial.
bitstream/item/106219/1/Boletim-195-web.pd
Myocarditis Mimicking an Acute Coronary Syndrome: A Case Related to Salmonella enteritis
Infective myocarditis is most commonly due to a viral infection; occasionally it has been related to bacteria. Gastrointestinal infections associated with myocarditis have only rarely been described in young people, and the pathogenesis is unclear. We report a case of myocarditis mimicking an acute coronary syndrome (ACS) in a patient hospitalized for fever and diarrhoea. Salmonella enteritidis was isolated from stool, and no other pathogens were found. The coronary angiography was normal, and there were not other coronary artery risk factors, other than hypertension. The patient was treated with ciprofloxacin, acetylsalicylate acid, and ramipril with rapid clinical improvement and normalization of cardiac abnormalities. Final diagnosis of Salmonella enteritis and related myocarditis was made based on clinical, laboratory, ECG and echocardiographical findings
Tecnologias para produção de citros na propriedade de base familiar.
bitstream/item/78773/1/Documento-343.pd
Three-dimensional racetrack memory devices designed from freestanding magnetic heterostructures
The fabrication of three-dimensional nanostructures is key to the development of next-generation nanoelectronic devices with a low device footprint. Magnetic racetrack memory encodes data in a series of magnetic domain walls that are moved by current pulses along magnetic nanowires. To date, most studies have focused on two-dimensional racetracks. Here we introduce a lift-off and transfer method to fabricate three-dimensional racetracks from freestanding magnetic heterostructures grown on a water-soluble sacrificial release layer. First, we create two-dimensional racetracks from freestanding films transferred onto sapphire substrates and show that they have nearly identical characteristics compared with the films before transfer. Second, we design three-dimensional racetracks by covering protrusions patterned on a sapphire wafer with freestanding magnetic heterostructures. We demonstrate current-induced domain-wall motion for synthetic antiferromagnetic three-dimensional racetracks with protrusions of up to 900ânm in height. Freestanding magnetic layers, as demonstrated here, may enable future spintronic devices with high packing density and low energy consumption
The Critical Properties of Two-dimensional Oscillator Arrays
We present a renormalization group study of two dimensional arrays of
oscillators, with dissipative, short range interactions. We consider the case
of non-identical oscillators, with distributed intrinsic frequencies within the
array and study the steady-state properties of the system. In two dimensions no
macroscopic mutual entrainment is found but, for identical oscillators,
critical behavior of the Berezinskii-Kosterlitz-Thouless type is shown to be
present. We then discuss the stability of (BKT) order in the physical case of
distributed quenched random frequencies. In order to do that, we show how the
steady-state dynamical properties of the two dimensional array of non-identical
oscillators are related to the equilibrium properties of the XY model with
quenched randomness, that has been already studied in the past. We propose a
novel set of recursion relations to study this system within the Migdal
Kadanoff renormalization group scheme, by mean of the discrete clock-state
formulation. We compute the phase diagram in the presence of random dissipative
coupling, at finite values of the clock state parameter. Possible experimental
applications in two dimensional arrays of microelectromechanical oscillators
are briefly suggested.Comment: Contribution to the conference "Viewing the World through Spin
Glasses" in honour of Professor David Sherrington on the occasion of his 65th
birthda
BMI can influence adult males' and females' airway hyperresponsiveness differently
BACKGROUND: Epidemiological data indicate that obesity is a risk factor for asthma, but scientific literature is still debating the association between changes in body mass index (BMI) and airway hyperresponsiveness (AHR). METHODS: This study aimed at evaluating the influence of BMI on AHR, in outpatients with symptoms suggestive of asthma. 4,217 consecutive adult subjects (2,439 M; mean age: 38.2±14.9 yrs; median FEV(1) % predicted: 100 [IQR:91.88-107.97] and FEV(1)/FVC % predicted: 85.77% [IQR:81.1-90.05]), performed a methacholine challenge test for suspected asthma. Subjects with PD(20) < 200 or 200 < PD(20) < 800 or PD(20) > 800 were considered affected by severe, moderate or mild AHR, respectively. RESULTS: A total of 2,520 subjects (60% of all cases) had a PD(20) < 3,200 ÎŒg, with a median PD(20) of 366 ÎŒg [IQR:168â1010.5]; 759, 997 and 764 patients were affected by mild, moderate and severe AHR, respectively. BMI was not associated with increasing AHR in males. On the contrary, obese females were at risk for AHR only when those with moderate AHR were considered (OR: 1.772 [1.250-2.512], p = 0.001). A significant reduction of FEV(1)/FVC for unit of BMI increase was found in moderate AHR, both in males (ÎČ = â0.255; p =0.023) and in females (ÎČ = â0.451; p =0.017). CONCLUSIONS: Our findings indicate that obesity influences AHR only in females with a moderate AHR level. This influence may be mediated by obesity-associated changes in baseline lung function
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