108 research outputs found

    Durational exposure-dependent effect of carbamate treated net on hepatic and renal functions in Wistar rats

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    Assessment of the duration exposure-dependent effect of carbamate treated net on hepatic and renal functions of albino Wistar rats after 30 and 60 days was carried out. Serum ALT, AST and ALP levels were determined to assess liver function while serum creatinine and urea levels were measured for kidney function. Eighteen (18) male albino Wstar rats weighing 138-146g were divided into 3 groups of 6 rats each. Group 1 served as control, group 2 animals were exposed to carbamate treated net for 30 days and group 3 animals exposed for 60 days. The results showed that the levels of serum AST and ALT increased in all the experimental groups exposed when compared to the control group. ALT increased significantly (p<0.05) in the rats exposed for 60 days (203.83±0.307) while AST increased highest in experimental groups exposed for 30 days (203± 1.613)and 60 days (362± 0.365) respectively when compared to the control (150.5±0.34). ALP increased significantly (p<0.05) only in the group exposed for 30 days (17.67±0.21),but decreased in the group exposed for 60 days when compared to the control group. Serum creatinine increased insignificantly (p>0.05) in the group exposed for 30 days but decreased in the group exposed for 60 days while serum urea level in the group exposed for 30 days remain unchanged but decreased after 60 days when compared to the control group. Statistically, there was a significant increase (p<0.05) in body weight and organ weight of the animals exposed for 30 and 60 days. Therefore, this present study demonstrates that exposure to carbamate treated net may alter the integrity and function of liver thereby causing hepatotoxicity while the exposure of rats to carbamate treated net may not pose any significant nephrotoxicity in rats

    Completeness of classical spin models and universal quantum computation

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    We study mappings between distinct classical spin systems that leave the partition function invariant. As recently shown in [Phys. Rev. Lett. 100, 110501 (2008)], the partition function of the 2D square lattice Ising model in the presence of an inhomogeneous magnetic field, can specialize to the partition function of any Ising system on an arbitrary graph. In this sense the 2D Ising model is said to be "complete". However, in order to obtain the above result, the coupling strengths on the 2D lattice must assume complex values, and thus do not allow for a physical interpretation. Here we show how a complete model with real -and, hence, "physical"- couplings can be obtained if the 3D Ising model is considered. We furthermore show how to map general q-state systems with possibly many-body interactions to the 2D Ising model with complex parameters, and give completeness results for these models with real parameters. We also demonstrate that the computational overhead in these constructions is in all relevant cases polynomial. These results are proved by invoking a recently found cross-connection between statistical mechanics and quantum information theory, where partition functions are expressed as quantum mechanical amplitudes. Within this framework, there exists a natural correspondence between many-body quantum states that allow universal quantum computation via local measurements only, and complete classical spin systems.Comment: 43 pages, 28 figure

    The role of government co-investment funds in the supply of entrepreneurial finance: An assessment of the early operation of the UK Angel Co-investment Fund

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    Co-investment funds – which invest alongside private investors, especially business angels – thereby leveraging their networks and experience and minimizing public sector transaction costs – are a recent approach by governments in various countries to address the early stage entrepreneurial funding gap which is perceived as a barrier to the ability of firms to scale-up. However, little literature exists on their operation, impact and effectiveness. This paper assesses the early operation of the UK’s Angel Co-investment Fund, established in 2011. Interview evidence from angels and business managers suggests that the Angel Co-investment Fund is improving the availability of finance by enabling firms to raise funding rounds of between £500,000 and £2 m, hence addressing some aspects of the broken finance escalator model. However, our evidence suggests that it is not yet impacting the supply side, either in terms of stimulating the formation of new angel groups or enhancing learning amongst less experienced angels. Some aspects of the operation of the investment process have attracted criticism from angels and entrepreneurs which need to be addressed. Nevertheless, there is sufficient evidence for positive impact to justify the scheme’s expansion

    Classical Ising model test for quantum circuits

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    We exploit a recently constructed mapping between quantum circuits and graphs in order to prove that circuits corresponding to certain planar graphs can be efficiently simulated classically. The proof uses an expression for the Ising model partition function in terms of quadratically signed weight enumerators (QWGTs), which are polynomials that arise naturally in an expansion of quantum circuits in terms of rotations involving Pauli matrices. We combine this expression with a known efficient classical algorithm for the Ising partition function of any planar graph in the absence of an external magnetic field, and the Robertson-Seymour theorem from graph theory. We give as an example a set of quantum circuits with a small number of non-nearest neighbor gates which admit an efficient classical simulation.Comment: 17 pages, 2 figures. v2: main result strengthened by removing oracular settin

    The transformation of the business angel market: empirical evidence and research implications

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    Business angel investing – a key source of finance for entrepreneurial businesses – is rapidly evolving from a fragmented and largely anonymous activity dominated by individuals investing on their own to one that is increasingly characterised by groups of investors investing together through managed angel groups. The implications of this change have been largely ignored by scholars. The paper examines the investment activity and operation of angel groups in Scotland to highlight the implications of this change for the nature of angel investing. It goes on to argue that this transformation challenges both the ongoing relevance of prior research on business angels and current methodological practices, and raises a set of new research questions

    Belief Propagation and Loop Series on Planar Graphs

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    We discuss a generic model of Bayesian inference with binary variables defined on edges of a planar graph. The Loop Calculus approach of [1, 2] is used to evaluate the resulting series expansion for the partition function. We show that, for planar graphs, truncating the series at single-connected loops reduces, via a map reminiscent of the Fisher transformation [3], to evaluating the partition function of the dimer matching model on an auxiliary planar graph. Thus, the truncated series can be easily re-summed, using the Pfaffian formula of Kasteleyn [4]. This allows to identify a big class of computationally tractable planar models reducible to a dimer model via the Belief Propagation (gauge) transformation. The Pfaffian representation can also be extended to the full Loop Series, in which case the expansion becomes a sum of Pfaffian contributions, each associated with dimer matchings on an extension to a subgraph of the original graph. Algorithmic consequences of the Pfaffian representation, as well as relations to quantum and non-planar models, are discussed.Comment: Accepted for publication in Journal of Statistical Mechanics: theory and experimen
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