1,047 research outputs found
A nonextensive approach to the dynamics of financial observables
We present results about financial market observables, specifically returns
and traded volumes. They are obtained within the current nonextensive
statistical mechanical framework based on the entropy
(). More precisely, we
present stochastic dynamical mechanisms which mimic probability density
functions empirically observed. These mechanisms provide possible
interpretations for the emergence of the entropic indices in the time
evolution of the corresponding observables. In addition to this, through
multi-fractal analysis of return time series, we verify that the dual relation
is numerically satisfied, and being
associated to the probability density function and to the sensitivity to
initial conditions respectively. This type of simple relation, whose
understanding remains ellusive, has been empirically verified in various other
systems.Comment: Invited paper to appear in special issue of Eur. Phys. J. B dedicated
to econophysics, edited by T. Di Matteo and T. Aste. 7 page
Use Of Organic Compost Containing Waste From Small Ruminants In Corn Production
Composting is a useful way of transforming livestock waste into organic fertilizer, which is proven to increase soil nutrient levels, and thus crop yield. Remains from production and slaughter of small ruminants can become a source of important elements for plant growth, such as N, after microorganism-driven decomposition.The aim of this investigation was to evaluate the effects of this compost on soil fertility and on the nutritional status and yield of the corn crop. The experiment was conducted in a Haplic Luvisol in a randomized block design with six treatments and five application rates of the organic compound in Mg ha-1: 3 (half the standard rate), 6 (standard rate), 9 (one and a half times the standard rate), 12 (twice the standard rate), and 24 (four times the standard rate) and an additional treatment with mineral fertilizers (110, 50 e 30 kg ha-1 of N, P2O5 and K2O, respectively), with four blocks. Evaluations were performed for two harvests of rainfed crops, measuring soil fertility, nutritional status, and grain yield. The compost increased P, K, Na and Zn values in the 0.00-0.20 m layer in relation of mineral fertilization in 616, 21, 114 and 90% with rate 24 Mg ha-1 in second crop. Leaf N, Mg, and S contents, relative chlorophyll content, and the productivity of corn kernels increased in 27, 32, 36, 20 e 85%, respectively, of low rate (3 Mg ha-1) to high rate (24 Mg ha-1) with of application of the compost. Corn yield was higher with application of organic compost in rate of 24 Mg ha-1 than mineral fertilizer combination in second crop. © 2016, Revista Brasileira de Ciencia do Solo. All rights reserved.4
The Developmental Competence of Oocytes Retrieved from The Leading Follicle in Controlled Ovarian Stimulated Cycles
Abstract Background: This study compares the developmental capacity of gametes retrieved from the largest follicle with small follicles of a cohort in controlled ovarian stimulated cycles
PAK2 is an effector of TSC1/2 signaling independent of mTOR and a potential therapeutic target for Tuberous Sclerosis Complex
Tuberous sclerosis complex (TSC) is caused by inactivating mutations in either TSC1 or TSC2 and is characterized by uncontrolled mTORC1 activation. Drugs that reduce mTOR activity are only partially successful in the treatment of TSC, suggesting that mTOR-independent pathways play a role in disease development. Here, kinome profiles of wild-type and Tsc2-/- mouse embryonic fibroblasts (MEFs) were generated, revealing a prominent role for PAK2 in signal transduction downstream of TSC1/2. Further investigation showed that the effect of the TSC1/2 complex on PAK2 is mediated through RHEB, but is independent of mTOR and p21RAC. We also demonstrated that PAK2 over-activation is likely responsible for the migratory and cell cycle abnormalities observed in Tsc2-/- MEFs. Finally, we detected high levels of PAK2 activation in giant cells in the brains of TSC patients. These results show that PAK2 is a direct effector of TSC1-TSC2-RHEB signaling and a new target for rational drug therapy in TSC
Invasive fungal diseases in haematopoietic cell transplant recipients and in patients with acute myeloid leukaemia or myelodysplasia in Brazil
AbstractInvasive fungal disease (IFD) shows distinct regional incidence patterns and epidemiological features depending on the geographic region. We conducted a prospective survey in eight centres in Brazil from May 2007 to July 2009. All haematopoietic cell transplant (HCT) recipients and patients with acute myeloid leukaemia (AML) or myelodysplasia (MDS) were followed from admission until 1 year (HCT) or end of consolidation therapy (AML/MDS). The 12-month cumulative incidence (CI) of proven or probable IFD was calculated, and curves were compared using the Grey test. Among 237 AML/MDS patients and 700 HCT recipients (378 allogeneic, 322 autologous), the 1-year CI of IFD in AML/MDS, allogeneic HCT and autologous HCT was 18.7%, 11.3% and 1.9% (p <0.001), respectively. Fusariosis (23 episodes), aspergillosis (20 episodes) and candidiasis (11 episodes) were the most frequent IFD. The 1-year CI of aspergillosis and fusariosis in AML/MDS, allogeneic HCT and autologous HCT were 13.4%, 2.3% and 0% (p <0.001), and 5.2%, 3.8% and 0.6% (p 0.01), respectively. The 6-week probability of survival was 53%, and was lower in cases of fusariosis (41%). We observed a high burden of IFD and a high incidence and mortality for fusariosis in this first multicentre epidemiological study of IFD in haematological patients in Brazil
Structural and spectroscopic investigation of the charge-ordered, short-range ordered, and disordered phases of the Co3O2BO3 ludwigite
Charge ordering is prone to occur in crystalline materials with mixed-valence ions. It is presumably accompanied by a structural phase transition, with possible exceptions in compounds that already present more than one inequivalent site for the mixed-valence ions in the charge-disordered phase. In this work, we investigate the representative case of the homometallic Co ludwigite Co2+2Co3+O2BO3 (Pbam space group) with four distinct Co crystallographic sites [M1–M4] surrounded by oxygen octahedra. The mixed-valent character of the Co ions up to at least T=873 K is verified through x-ray absorption near-edge structure (XANES) experiments. Single crystal x-ray diffraction (XRD) and neutron powder diffraction (NPD) confirm that the Co ions at the M4 site are much smaller than the others at low temperatures, consistent with a Co3+ oxidation state at M4 and Co2+ at the remaining sites. The size difference between the Co ions in the M4 and M2 sites is continuously reduced upon warming above ≈370 K, indicating a gradual charge redistribution within the M4−M2−M4 (424) ladder in the average structure. Minor structural anomalies with no space group modification are observed near 475 and 495 K, where sharp phase transitions were previously revealed by calorimetry and electrical resistivity data. An increasing structural disorder, beyond a conventional thermal effect, is noted above ≈370 K, manifested by an anomalous increment of XRD Debye-Waller factors and broadened vibrational modes observed by Raman scattering. The local Co-O distance distribution, revealed by Co K-edge extended x-ray absorption fine structure (EXAFS) data and analyzed with an evolutionary algorithm method, is similar to that inferred from the XRD crystal structure below ≈370 K. At higher temperatures, the local Co-O distance distribution remains similar to that found at low temperatures, at variance with the average crystal structure obtained with XRD. We conclude that the oxidation states Co2+ and Co3+ are instantaneously well defined in a local atomic level at all temperatures, however the thermal energy promotes local defects in the charge-ordered configuration of the 424 ladders upon warming. These defects coalesce into a phase-segregated state within a narrow temperature interval (475<T<495 K). Finally, a transition at ≈500 K revealed by differential scanning calorimetry (DSC) in the iron ludwigite Fe3O2BO3 is discussed
Viability of Noether symmetry of F(R) theory of gravity
Canonization of F(R) theory of gravity to explore Noether symmetry is
performed treating R - 6(\frac{\ddot a}{a} + \frac{\dot a^2}{a^2} +
\frac{k}{a^2}) = 0 as a constraint of the theory in Robertson-Walker
space-time, which implies that R is taken as an auxiliary variable. Although it
yields correct field equations, Noether symmetry does not allow linear term in
the action, and as such does not produce a viable cosmological model. Here, we
show that this technique of exploring Noether symmetry does not allow even a
non-linear form of F(R), if the configuration space is enlarged by including a
scalar field in addition, or taking anisotropic models into account.
Surprisingly enough, it does not reproduce the symmetry that already exists in
the literature (A. K. Sanyal, B. Modak, C. Rubano and E. Piedipalumbo,
Gen.Relativ.Grav.37, 407 (2005), arXiv:astro-ph/0310610) for scalar tensor
theory of gravity in the presence of R^2 term. Thus, R can not be treated as an
auxiliary variable and hence Noether symmetry of arbitrary form of F(R) theory
of gravity remains obscure. However, there exists in general, a conserved
current for F(R) theory of gravity in the presence of a non-minimally coupled
scalar-tensor theory (A. K. Sanyal, Phys.Lett.B624, 81 (2005),
arXiv:hep-th/0504021 and Mod.Phys.Lett.A25, 2667 (2010), arXiv:0910.2385
[astro-ph.CO]). Here, we briefly expatiate the non-Noether conserved current
and cite an example to reveal its importance in finding cosmological solution
for such an action, taking F(R) \propto R^{3/2}.Comment: 16 pages, 1 figure. appears in Int J Theoretical Phys (2012
Energy resolution and energy-light response of CsI(TI) scintillators for charged particle detection
This article describes the crystal selection and quality control utilized to
develop and calibrate a high resolution array of CsI(TI) scintillator crystals
for the detection of energetic charged particles. Alpha sources are used to
test the light output variation due to thallium doping gradients. Selection of
crystals with better than 1% non-uniformity in light output is accomplished
using this method. Tests with 240 MeV alpha beam reveal that local light output
variations within each of the tested CsI(TI) crystals limit the resolution to
about 0.5%. Charge and mass dependences in the energy - light output
relationship are determined by calibrating with energetic projectile
fragmentation beams.Comment: 24 pages, 7 figure
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