Localised projective measurement of a relativistic quantum field in non-inertial frames

We propose a scheme to study the effect of motion on measurements of a quantum field carried out by a finite-size detector. We introduce a model of projective detection of a localised field mode in an arbitrary reference frame. We apply it to extract vacuum entanglement by a pair of counter-accelerating detectors and to estimate the Unruh temperature of a single accelerated detector. The introduced method allows us to directly relate the observed effects with the instantaneous proper acceleration of the detector.Comment: 5 pages, 2 figures. v2 Significant increase in the detail level regarding the motivation of the detector mode

Linearization of nonlinear connections on vector and affine bundles, and some applications

A linear connection is associated to a nonlinear connection on a vector bundle by a linearization procedure. Our definition is intrinsic in terms of vector fields on the bundle. For a connection on an affine bundle our procedure can be applied after homogenization and restriction. Several applications in Classical Mechanics are provided

The entangling side of the Unruh-Hawking effect

We show that the Unruh effect can create net quantum entanglement between inertial and accelerated observers depending on the choice of the inertial state. This striking result banishes the extended belief that the Unruh effect can only destroy entanglement and furthermore provides a new and unexpected source for finding experimental evidence of the Unruh and Hawking effects.Comment: 4 pages, 4 figures. Added Journal referenc

Red nucleus and rubrospinal tract disorganization in the absence of Pou4f1

The red nucleus (RN) is a neuronal population that plays an important role in forelimb motor control and locomotion. Histologically it is subdivided into two subpopulations, the parvocellular RN (pRN) located in the diencephalon and the magnocellular RN (mRN) in the mesencephalon. The RN integrates signals from motor cortex and cerebellum and projects to spinal cord interneurons and motor neurons through the rubrospinal tract (RST). Pou4f1 is a transcription factor highly expressed in this nucleus that has been related to its specification. Here we profoundly analyzed consequences of Pou4f1 loss-of-function in development, maturation and axonal projection of the RN. Surprisingly, RN neurons are specified and maintained in the mutant, no cell death was detected. Nevertheless, the nucleus appeared disorganized with a strong delay in radial migration and with a wider neuronal distribution; the neurons did not form a compacted population as they do in controls, Robo1 and Slit2 were miss-expressed. Cplx1 and Npas1, expressed in the RN, are transcription factors involved in neurotransmitter release, neuronal maturation and motor function processes among others. In our mutant mice, both transcription factors are lost, suggesting an abnormal maturation of the RN. The resulting altered nucleus occupied a wider territory. Finally, we examined RST development and found that the RN neurons were able to project to the spinal cord but their axons appeared defasciculated. These data suggest that Pou4f1 is necessary for the maturation of RN neurons but not for their specification and maintenance.Peer reviewedPeer Reviewe

Procesos hidrogeoquímicos en las aguas subterráneas de la cuenca de la laguna Mar Chiquita, provincia de Buenos Aires

Fil: Glok Galli, Melisa. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata; ArgentinaFil: Martínez, Daniel E.. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata; ArgentinaFil: Kruse, Eduardo Emilio. Cátedra de Hidrología General. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Lima, María Lourdes. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata; Argentin

Amphiura chiajei Forbes, comensal de Maldane glebifex Grube, en la Ría de Muros (Galicia)

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Radiocarbon reservoir ages and hardwater effect for the northeastern coastal waters of Argentina

Accelerator mass spectrometry (AMS) radiocarbon dates were obtained for 18 mollusk shells collected alive along the Buenos Aires province coast, Argentina, over the period AD 1914-1935. Reservoir ages were estimated for all samples on the basis of the tree-ring calibration curve for the Southern Hemisphere (SHCal04, McCormac et al. 2004) and the marine ΔR values calculated as the difference between the conventional 14C age and the age deduced from the marine, mixed-layer model calculation (Marine04, Hughen et al. 2004). For most coastal locations, a great ΔR scatter was observed, ranging from 191 to 2482 yr, which is explained by the input of varying content of dissolved carbonate by rivers and groundwater ("hardwater effect") and indicates a serious limitation for shell-based 14C chronologies. Within the interior of Bahía Blanca estuary, ΔR values ranged from -40 to 50 ± 46 as a consequence of the local geological particularities of the environment. This suggests that, with some restrictions, the marine calibration curve with standard parameters (ΔR = 0) could be used at this location.Facultad de Ciencias Naturales y Muse

Neuroprotective Effects of Betulinic Acid Hydroxamate in Intraventricular Hemorrhage-Induced Brain Damage in Immature Rats

Intraventricular hemorrhage (IVH) is an important cause of long-term disability in extremely preterm infants, with no current treatment. We aimed to study in an IVH model in immature rats the neuroprotective effect of betulinic acid hydroxamate (BAH), a B55α/PP2A activator that inhibits the activity of the hypoxia-inducing factor prolyl-hydroxylase type 2. IVH was induced in 1-day-old (P1) Wistar rats by the left periventricular injection of Clostridial collagenase. Then, pups received i.p. vehicle or BAH 3 mg/kg single dose. At P6, P14 and P45, brain damage (area of damage, neurobehavioral deficits, Lactate/N-acetylaspartate ratio), white matter injury (WMI: corpus callosum atrophy and myelin basic protein signal reduction) and inflammation (TLR4, NF-κB and TNFα expression), excitotoxicity (Glutamate/N-acetylspartate) and oxidative stress (protein nitrosylation) were evaluated. BAH treatment did not reduce the volume of brain damage, but it did reduce perilesional tissue damage, preventing an IVH-induced increase in Lac/NAA. BAH restored neurobehavioral performance at P45 preventing WMI. BAH prevented an IVH-induced increase in inflammation, excitotoxicity and oxidative stress. In conclusion, in immature rats, BAH reduced IVH-induced brain damage and prevented its long-term functional consequences, preserving normal myelination in a manner related to the modulation of inflammation, excitotoxicity and oxidative stress

Classical field theory on Lie algebroids: Variational aspects

The variational formalism for classical field theories is extended to the setting of Lie algebroids. Given a Lagrangian function we study the problem of finding critical points of the action functional when we restrict the fields to be morphisms of Lie algebroids. In addition to the standard case, our formalism includes as particular examples the case of systems with symmetry (covariant Euler-Poincare and Lagrange Poincare cases), Sigma models or Chern-Simons theories.Comment: Talk deliverd at the 9th International Conference on Differential Geometry and its Applications, Prague, September 2004. References adde

Contribution of infauna and mussel-raft epifauna to demersal fish diets

The contribution of infauna and mussel-raft epifauna to the diet of 3 dominant species in the demersal fish community of the Ria de Arosa, N. W. Spain - Lesueurigobius friesii (Gobiidae), Callionymus lyra (Callionymidae) and Trisopterus luscus (Gadidae) - was determined. Intense raft mussel culture in the Ria de Arosa supports a rich epifauna which constitutes the main food resource for the fishes studied. In contrast, infauna density is low and contributes only a small proportion to fish diets. Prey consumed was similar in the 3 fish species. Gut contents consisted mainly of the small crab Pisidia longicornis. This decapod is a dominant component of the raft epifauna, and electivity indices indicate that it is selected by the fishes. In the Ria de Pontevedra, which contains fewer mussel rafts, these fish fed on infauna. Thus, one effect of intense mussel aquaculture has been to change the food habits of these 3 fishes from predominantly infauna to raft epifauna diet.versión del edito