555 research outputs found
Generalized Chern-Simons Modified Gravity in First-Order Formalism
We propose a generalization of Chern-Simons (CS) modified gravity in
first-order formalism. CS modified gravity action has a term that comes from
the chiral anomaly which is Pontryagin invariant. First-order CS modified
gravity is a torsional theory and in a space-time with torsion the chiral
anomaly includes a torsional topological term called Nieh-Yan invariant. We
generalize the CS modified gravity by adding the Nieh-Yan term to the action
and find the effective theory. We compare the generalized theory with the
first-order CS modified gravity and comment on the similarities and
differences.Comment: 8 pages, an author added, new paragraphs, comments and references
added, published in Gen. Relativ. Gravi
Efecto de la alimentación restringida en la etapa de engorde sobre una población de cerdos no mejorados
Se alimentaron dos grupos de cerdos no mejorados, uno a voluntad (T1) Y otro en restricción (T2) durante la etapa de engorde. El objetivo fue evaluar las características productivas cualitativas y cuantitativas en relación a la ganancia diaria de peso, eficiencia de conversión alimenticia, días a faena, espesor de grasa dorsal en el cerdo vivo y en la res, porcentaje de tejido magro y rendimiento de la res. Los grupos que estuvieron constituidos por 15 machos castrados y 15 hembras sin servicio cada uno y se alimentaron desde los 64,62 Kg ± 0.95 hasta los 104,92 Kg ± 5.36 de peso vivo, en pistas de cemento. A ambos grupos se les suministró una ración cuya composición fue de 14% de P.B., 3100 kcal de EO/kg; 0,75% Ca, 0,50% de P y 0,83% de lisina, A los cerdos en restricción se les proveyó la ración fraccionada cuatro veces al día y el nivel de restricción se estableció para seis periodos de 14 días cada uno (ración diaria = 2,6 kg; 2,8; 2,8; 3,0 Y 3,9 respectivamente) Los resultados en promedio, indicaron diferencias significativas entre tratamientos (p<0,05) en los siguientes parámetros: Ganancia diaria de peso (g) TI = 780,5 Y T2= 528; Olas a faena: TI= 57 Y T2= 86, Espesor de grasa dorsal in vivo (mm) T= 24,57 Y T2= 22,05, Magro (5) TI= 42,15 Y T2= 44,85; Espesor de grasa dorsal en la res (mm) TI= 25 65 Y T2= 23,30 Y Rendimiento de la res (5) TI= 80 T2= 78,55. Las hembras del TI tuvieron una ganancia diaria de peso significativamente menor que los machos castrados (Machos = 720 g Y Hembras = 625 g. p<0,05). Los animales restringidos consumieron 45 g menos de alimento por día que los alimentados a voluntad y la eficiencia de conversión alimenticia fue de 4,45: 1.Director: Ing. Agr. Jorge E. Cervellini. Cátedra de Zootecnia especial Il. Facultad de Agronomía. UNLPam.Co-Director: lng. Agr. Rodolfo O. Braun. Cátedra de Zootecnia especial Il. Facultad de Agronomía. UNLPam
Automatic Segmentation of Muscle Tissue and Inter-muscular Fat in Thigh and Calf MRI Images
Magnetic resonance imaging (MRI) of thigh and calf muscles is one of the most
effective techniques for estimating fat infiltration into muscular dystrophies.
The infiltration of adipose tissue into the diseased muscle region varies in
its severity across, and within, patients. In order to efficiently quantify the
infiltration of fat, accurate segmentation of muscle and fat is needed. An
estimation of the amount of infiltrated fat is typically done visually by
experts. Several algorithmic solutions have been proposed for automatic
segmentation. While these methods may work well in mild cases, they struggle in
moderate and severe cases due to the high variability in the intensity of
infiltration, and the tissue's heterogeneous nature. To address these
challenges, we propose a deep-learning approach, producing robust results with
high Dice Similarity Coefficient (DSC) of 0.964, 0.917 and 0.933 for
muscle-region, healthy muscle and inter-muscular adipose tissue (IMAT)
segmentation, respectively.Comment: 9 pages, 4 figures, 2 tables, MICCAI 2019, the 22nd International
Conference on Medical Image Computing and Computer Assisted Interventio
Corrigendum to “Pollen-based paleoenvironmental and paleoclimatic change at Lake Ohrid (south-eastern Europe) during the past 500 ka” published in Biogeosciences, 13, 1423–1437, 2016
In this corrigendum we report an updated pollen record from the Lake Ohrid DEEP site spanning the past 500 ka whereby we have reprocessed and re-analyzed 104 samples affected by chemical procedure problems that occurred in one palynological laboratory. Firstly, these samples were affected by the use of wrong containers, causing in- adequate settling of particles at the set centrifuging speed. Secondly, HCl and HF treatments were combined without the prescribed intermediate centrifuging and decanting steps. The inaccuracy in the protocol resulted in the loss of smaller pollen grains and in the overrepresentation of bisaccate ones in most of the re-analyzed samples. We therefore provide an updated set of figures with the new data and have revised the description of the results, discussion and conclusions re- ported in Sadori et al. (2016) where necessary. We stress that the majority of the original results and conclusions remain valid, while the records’ reliability and resolution have improved as 12 samples that had been omitted in the original study because of low count sums are now included in the revised dataset (Sadori et al., 2018)
Identification of a Response Amplitude Operator for Ships
At the European Study Group Mathematics with Industry 2012 in Eindhoven, the Maritime Research Institute Netherlands (MARIN) presented the problem of identifying the response amplitude operator (RAO) for a ship, given input information on the amplitudes of the sea waves and output information on the movement of the ship. We approach the problem from a threefold perspective: a direct least-squares approach, an approach based on truncated Fourier series, and an approach using low-dimensional measures of the RAO. We give a few recommendations for possible further investigations
The Holst Action by the Spectral Action Principle
We investigate the Holst action for closed Riemannian 4-manifolds with
orthogonal connections. For connections whose torsion has zero Cartan type
component we show that the Holst action can be recovered from the heat
asymptotics for the natural Dirac operator acting on left-handed spinor fields.Comment: We correct a sign mistake in Proposition 2.3. As a consequence the
main result (Theorem 3.4) becomes more natura
Selective laser sintering of hydroxyapatite reinforced polyethylene composites for bioactive implants and tissue scaffold development
Selective laser sintering (SLS) has been investigated for the production of bioactive implants and tissue scaffolds using composites of high-density polyethylene (HDPE) reinforced with hydroxyapatite (HA) with the aim of achieving the rapid manufacturing of customized implants. Single-layer and multilayer block specimens made of HA-HDPE composites with 30 and 40 vol % HA were sintered successfully using a CO2 laser sintering system. Laser power and scanning speed had a significant effect on the sintering behaviour. The degree of particle fusion and porosity were influenced by the laser processing parameters, hence control can be attained by varying these parameters. Moreover, the SLS processing allowed exposure of HA particles on the surface of the composites and thereby should provide bioactive products. Pores existed in the SLS-fabricated composite parts and at certain processing parameters a significant fraction of the pores were within the optimal sizes for tissue regeneration. The results indicate that the SLS technique has the potential not only to fabricate HA-HDPE composite products but also to produce appropriate features for their application as bioactive implants and tissue scaffolds
Dopamine D_2-receptor activation elicits akinesia, rigidity, catalepsy, and tremor in mice expressing hypersensitive 4 nicotinic receptors via a cholinergic-dependent mechanism
Recent studies suggest that high-affinity neuronal nicotinic acetylcholine receptors (nAChRs) containing α4 and β2 subunits (α4β2*) functionally interact with G-protein-coupled dopamine (DA) D_2 receptors in basal ganglia. We hypothesized that if a functional interaction between these receptors exists, then mice expressing an M2 point mutation (Leu9'Ala) rendering 4 nAChRs hypersensitive to ACh may exhibit altered sensitivity to a D_2-receptor agonist. When challenged with the D_(2)R agonist, quinpirole (0.5–10 mg/kg), Leu9'Ala mice, but not wild-type (WT) littermates, developed severe, reversible motor impairment characterized by rigidity, catalepsy, akinesia, and tremor. While striatal DA tissue content, baseline release, and quinpirole-induced DA depletion did not differ between Leu9'Ala and WT mice, quinpirole dramatically increased activity of cholinergic striatal interneurons only in mutant animals, as measured by increased c-Fos expression in choline acetyltransferase (ChAT)-positive interneurons. Highlighting the importance of the cholinergic system in this mouse model, inhibiting the effects of ACh by blocking muscarinic receptors, or by selectively activating hypersensitive nAChRs with nicotine, rescued motor symptoms. This novel mouse model mimics the imbalance between striatal DA/ACh function associated with severe motor impairment in disorders such as Parkinson’s disease, and the data suggest that a D_(2)R–α4*-nAChR functional interaction regulates cholinergic interneuron activity.—Zhao-Shea, R., Cohen, B. N., Just, H., McClure-Begley, T., Whiteaker, P., Grady, S. R., Salminen, O., Gardner, P. D., Lester, H. A., Tapper, A. R. Dopamine D2-receptor activation elicits akinesia, rigidity, catalepsy, and tremor in mice expressing hypersensitive α4 nicotinic receptors via a cholinergic-dependent mechanism
Neuropsychiatric, neuropsychological, and neuroimaging features in isolated REM sleep behavior disorder: The importance of MCI
Mild cognitive impairment (MCI) is frequently diagnosed in patients with isolated rapid eye movement (REM) sleep behavior disorder (iRBD), although the extent of MCI-associated neuropathology has not yet been quantified. The present study compared the differences in neuropsychiatric, neuropsychological, and neuroimaging markers of neurodegeneration in MCI-iRBD and iRBD patients with normal cognition
Convex domains of Finsler and Riemannian manifolds
A detailed study of the notions of convexity for a hypersurface in a Finsler
manifold is carried out. In particular, the infinitesimal and local notions of
convexity are shown to be equivalent. Our approach differs from Bishop's one in
his classical result (Bishop, Indiana Univ Math J 24:169-172, 1974) for the
Riemannian case. Ours not only can be extended to the Finsler setting but it
also reduces the typical requirements of differentiability for the metric and
it yields consequences on the multiplicity of connecting geodesics in the
convex domain defined by the hypersurface.Comment: 22 pages, AMSLaTex. Typos corrected, references update
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