Ground-State Entanglement of the BCS Model

The concept of local concurrence is used to quantify the entanglement between a single qubit and the remainder of a multiqubit system. For the ground state of the BCS model in the thermodynamic limit the set of local concurrences completely describes the entanglement. As a measure for the entanglement of the full system we investigate the average local concurrence (ALC). We find that the ALC satisfies a simple relation with the order parameter. We then show that for finite systems with a fixed particle number, a relation between the ALC and the condensation energy exposes a threshold coupling. Below the threshold, entanglement measures besides the ALC are significant.

A model of migrants' remittances with human capital investment and intrafamilial transfers

This study analyzes data on migrants' remittances using a two-period theory of intergenerational transfers based on an informal, intrafamilial loan arrangement using weak altruism, a behavior between strong altruism and pure self-interest. The model provides an integrated theory of migrants' remittances, human capital investment decisions, and intrafamilial transfers applicable to low-income countries with no official pension schemes and imperfect capital markets. Propositions, derived from the theory, are tested, re-analyzing original survey data on remittances of Pacific island migrants in Sydney. When weak altruism and strong altruism yield opposite predictions, the econometric results tend to confirm the former hypothesis and invalidate the latter.

MORPHOLOGICAL CASTE DIFFERENCES IN POLYBIA AEQUATORIALIS (HYMENOPTERA: VESPIDAE: POLISTINAE: EPIPONINI), A SOCIAL WASP OF THE HIGHLANDS OF COSTA RICA

Many aspects of the biology and organization of Neotropical social wasps in the highlands are unknown. Polybia aequatorialis is a highland wasp of Costa Rica distributed between 1, 150 and 3,200 m in altitude, and little information on this species is recorded. We investigated the size of a colony of P. aequatorialis in the Cerro de la Muerte region of Costa Rica, and studied the morphological differences between queens and workers. Measures were taken from 248 reproductive and non-reproductive females, and caste differentiation was analyzed by Discrimination Function Analysis. We did not find a highly pronounced caste distinction in P. aequatorialis, even though ANOVA showed that queens and workers differed in all morphometric measures. The morphological differences between the reproductive and non-reproductive females probably results from a developmental switch, which is a characteristic caste syndrome of Polybia.

Soil morphological control on saline and freshwater lake hydrogeochemistry in the Pantanal of Nhecolandia, Brazil

Joint pedological, geochemical, hydrological and geophysical investigations were performed to study the coexistence or saline and freshwater lakes in close proximity and similar climatic conditions in the Nhecolandia region, Pantanal wetlands in Brazil. The saline lakes are concentrically surrounded by green sandy loam horizons, which cause differential hydrological regimes. Mg-calcite, K-silicates, and amorphous silica precipitate in the soil cover, whereas Mg-silicates and more soluble Na-carbonates are concentrated in the topsoil along the shore of the saline lake. In saline solutions, some minor elements (As, Se) reach values above the water quality recommendations, whereas others are controlled and incorporated in solid phases (Ba, Sr). Locally, the destruction of the sandy loam horizons generates very acidic soil solution (pH similar to 3.5) through a process not yet understood. The soil distributions indicate that some freshwater lakes are former saline lakes. They are invaded by freshwater after destruction of the sandy loam green horizons, then the freshwater becomes enriched in K(+), SO(4)(2-), Fe, Al, and a stream of minor and trace elements. The formation of these green sandy loam horizons in the saline environment and their destruction in the non-saline one emphasizes the dynamic nature of this environment (C) 2008 Elsevier B.V. All rights reserved.

Amphetamine modulates cellular recruitment and airway reactivity in a rat model of allergic lung inflammation

Asthma is characterized by pulmonary cellular infiltration, vascular exudation and airway hyperresponsiveness. Several drugs that modify central nervous system (CNS) activity can modulate the course of asthma. Amphetamine (AMPH) is a highly abused drug that presents potent stimulating effects on the CNS and has been shown to induce behavioral, biochemical and immunological effects. The purpose of this study was to investigate the effects of AMPH on pulmonary cellular influx, vascular permeability and airway reactivity. AMPH effects on adhesion molecule expression, IL-10 and IL-4 release and mast cell degranulation were also studied. Male Wistar rats were sensitized with ovalbumin (OVA) plus alum via subcutaneous injection. One week later, the rats received another injection of OVA-alum (booster). Two weeks after this booster, the rats were subjected to AMPH treatment 12 h prior to the OVA airway challenge. In rats treated with AMPH, the OVA challenge reduced cell recruitment into the lung, the vascular permeability and the cellular expression of ICAM-1 and Mac-1. Additionally, elevated levels of IL-10 and IL-4 were found in samples of lung explants from allergic rats. AMPH treatment, in comparison, increased IL-10 levels but reduced those of IL-4 in the lung explants. Moreover, the tracheal responsiveness to methacholine (MCh), as well as to an in vitro OVA challenge, was reduced by AMPH treatment, and levels of PCA titers were not modified by the drug. Our findings suggest that single AMPH treatment down-regulates several parameters of lung inflammation, such as cellular migration, vascular permeability and tracheal responsiveness. These results also indicate that AMPH actions on allergic lung inflammation include endothelium-leukocyte interaction mechanisms, cytokine release and mast cell degranulation. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Effect of the immunosuppressants on hepatocyte proliferation and apoptosis in a young animal model of liver regeneration: An immunohistochemical study using tissue microarrays

Hepatocyte proliferation and apoptosis (programmed cell death) occur during the liver parenchyma regeneration and the liver size modeling is mainly controlled by hepatocyte apoptosis. The purpose of the present study was to verify the influence of immunosuppressant drugs on these phenomena by utilizing tissue microarray techniques. Thirty-six weaning rats (age 21-23 days, weight 30-50 g) were divided into six groups: control, sham, hepatectomy, hepatectomy plus solumedrol, hepatectomy plus CsA, and hepatectomy plus Tac. The animals were killed one day after hepatectomy, and the remnant livers were weighed and harvested for tissue microarray sections. Liver cell proliferation was evaluated by staining for PCNA and apoptosis was detected by the TUNEL method. It was verified that CsA promoted a decrease in the liver weight, Tac and CsA decreased the proliferation index of hepatocytes, and glucocorticoid had no significant effects. The apoptosis index was not altered by hepatectomy or immunosuppressants. Our data indicate that, in the growing rat, CsA and Tac have negative effects on hepatocyte proliferation and have no effect on the hepatocyte apoptosis.

Early Brief Treatment with Losartan plus Mycophenolate Mofetil Provides Lasting Renoprotection in a Renal Ablation Model

Background: Inflammatory events antecede established renal injury in rats with 5/6 renal ablation (Nx), as indicated by the beneficial effects of early, uninterrupted treatment with mycophenolate mofetil (MMF). Angiotensin II also exerts a major pathogenic role at this initial phase. We investigated whether losartan (L) or L+MMF treatment, started early, and L+MMF treatment, started late, would exert lasting renoprotection in Nx even after being discontinued. Methods: Adult male Munich-Wistar rats underwent Nx and were divided into three groups: Nx (untreated), Nx(L) (given L), and Nx(LMMF) (given L and MMF). Protocol 1: treatments began on day 1, and ceased on day 30, after Nx. Protocol 2: L+MMF treatment began on day 30 and ceased on day 60. Results: Protocol 1: on day 30, hypertension, albuminuria and renal injury were strongly attenuated in Groups Nx(L) and Nx(LMMF). On day 120, these abnormalities were still attenuated in group Nx(LMMF). Protocol 2: on day 120, all parameters were similar between this late Nx(LMMF) group and untreated Nx. Conclusion: In Nx, temporary suppression of early, transitory hemodynamic/inflammatory phenomena affords relatively durable renoprotection even after treatment discontinuation. This effect is not obtained with similar temporary treatment initiated later in the course of renal disease. Copyright (C) 2010 S. Karger AG, Basel

Developmental vitamin D deficiency alters adult behaviour: An informative animal model of schizophrenia

Background: There is growing evidence that vitamin D is active in the brain but until recently there was a lack of evidence about its role during brain development. Guided by certain features of the epidemiology of schizophrenia, we have explored the role of vitamin D in the developing brain and behaviour using whole animal models. Methods: Sprague-Dawley rats were fed a vitamin D deficient diet (DVD) or control diet 6 weeks prior to mating and housed under UVB-free lighting conditions. On the day of birth all rats were fed a control diet for the remainder of the study. We observed behaviour at two timepoints; on the day of birth to study maternal behaviour, and at 10 weeks of age to study offspring behaviour in adulthood, under baseline and drug induced conditions (MK-801, haloperidol, amphetamine). Results: Prenatal vitamin D deficiency results in subtle alterations in maternal behaviour as well as long lasting effects on the adult offspring, despite a return to normal vitamin D levels during postnatal life. These affects were specific to transient prenatal vitamin D depletion as adult vitamin D depletion, combined prenatal and chronic postnatal vitamin D depletion, or ablation of the vitamin D receptor in mice led to markedly different outcomes. Conclusions: The developmental vitamin D (DVD) model now draws strength from epidemiological evidence of schizophrenia and animal experiments. Although the DVD model does not replicate every aspect of schizophrenia, it has several attractive features: (1) the exposure is based on clues from epidemiology; (2) it reproduces the increase in lateral ventricles; (3) it reproduces well-regarded behavioural phenotypes associated with schizophrenia (e.g. MK- 801 induced hyperlocomotion); and (4) it implicates a disturbance in dopamine signaling. In summary, low prenatal levels of vitamin D can influence critical components of orderly brain development and that this has a long lasting effect on behaviour.

Bile duct ligation in neonatal rats: Is it a valid experimental model for biliary atresia studies?

BA is the most important disease requiring liver transplantation in children. Common BDL in rats is a classic experimental model to study biliary obstruction. The response of the neonatal animal to BDL has yet to be completely understood and few reports have focused on the behavioral differences of the liver between neonatal and adult animals. Ninety newborn Wistar rats aged six days, weighing 8.0-13.9 g, and 90 adult Wistar rats weighing 199.7-357.0 g, were submitted to BDL. After surgery, they were randomly divided and killed on the 3rd, 5th, 7th, 14th, 21st and 28th day post-BDL. Hepatic biopsies were obtained and the following were measured: (i) semiquantification of the bile ductule proliferation and inflammatory infiltrate by HE stain, (ii) quanti. cation of portal and periportal fibrosis with the Sirius-red stain. Although the initial response of ductule proliferation and inflammatory infiltrate were less intense in the newborn animal, the portal and periportal fibrosis were higher when compared with adult animals (p < 0.0491). These findings may contribute to the understanding of the pathophysiology of BA.

AT(1) blockade during lactation as a model of chronic nephropathy: mechanisms of renal injury

Suppression of the renin-angiotensin system during lactation causes irreversible renal structural changes. In this study we investigated 1) the time course and the mechanisms underlying the chronic kidney disease caused by administration of the AT(1) receptor blocker losartan during lactation, and 2) whether this untoward effect can be used to engender a new model of chronic kidney disease. Male Munich-Wistar pups were divided into two groups: C, whose mothers were untreated, and L(Lact), whose mothers received oral losartan (250 mg.kg(-1).day(-1)) during the first 20 days after delivery. At 3 mo of life, both nephron number and the glomerular filtration rate were reduced in L(Lact) rats, whereas glomerular pressure was elevated. Unselective proteinuria and decreased expression of the zonula occludens-1 protein were also observed, along with modest glomerulosclerosis, significant interstitial expansion and inflammation, and wide glomerular volume variation, with a stable subpopulation of exceedingly small glomeruli. In addition, the urine osmolality was persistently lower in L(Lact) rats. At 10 mo of age, L(Lact) rats exhibited systemic hypertension, heavy albuminuria, substantial glomerulosclerosis, severe renal interstitial expansion and inflammation, and creatinine retention. Conclusions are that 1) oral losartan during lactation can be used as a simple and easily reproducible model of chronic kidney disease in adult life, associated with low mortality and no arterial hypertension until advanced stages; and 2) the mechanisms involved in the progression of renal injury in this model include glomerular hypertension, glomerular hypertrophy, podocyte injury, and interstitial inflammation.

Three-dimensional model for multi-component reactive transport with variable density groundwater flow

PHWAT is a new model that couples a geochemical reaction model (PHREEQC-2) with a density-dependent groundwater flow and solute transport model (SEAWAT) using the split-operator approach. PHWAT was developed to simulate multi-component reactive transport in variable density groundwater flow. Fluid density in PHWAT depends not on only the concentration of a single species as in SEAWAT, but also the concentrations of other dissolved chemicals that can be subject to reactive processes. Simulation results of PHWAT and PHREEQC-2 were compared in their predictions of effluent concentration from a column experiment. Both models produced identical results, showing that PHWAT has correctly coupled the sub-packages. PHWAT was then applied to the simulation of a tank experiment in which seawater intrusion was accompanied by cation exchange. The density dependence of the intrusion and the snow-plough effect in the breakthrough curves were reflected in the model simulations, which were in good agreement with the measured breakthrough data. Comparison simulations that, in turn, excluded density effects and reactions allowed us to quantify the marked effect of ignoring these processes. Next, we explored numerical issues involved in the practical application of PHWAT using the example of a dense plume flowing into a tank containing fresh water. It was shown that PHWAT could model physically unstable flow and that numerical instabilities were suppressed. Physical instability developed in the model in accordance with the increase of the modified Rayleigh number for density-dependent flow, in agreement with previous research. (c) 2004 Elsevier Ltd. All rights reserved.