323,563 research outputs found
When-and how- can a cellular automaton be rewritten as a lattice gas?
No full textAbstractBoth cellular automata (CA) and lattice-gas automata (LG) provide finite algorithmic presentations for certain classes of infinite dynamical systems studied by symbolic dynamics; it is customary to use the terms ‘cellular automaton’ and ‘lattice gas’ for a dynamic system itself as well as for its presentation. The two kinds of presentation share many traits but also display profound differences on issues ranging from decidability to modeling convenience and physical implementability.Following a conjecture by Toffoli and Margolus, it had been proved by Kari that any invertible CA, at least up to two dimensions, can be rewritten as an isomorphic LG. But until now it was not known whether this is possible in general for noninvertible CA—which comprise “almost all” CA and represent the bulk of examples in theory and applications. Even circumstantial evidence–whether in favor or against–was lacking.Here, for noninvertible CA, (a) we prove that an LG presentation is out of the question for the vanishingly small class of surjective ones. We then turn our attention to all the rest–noninvertible and nonsurjective–which comprise all the typical ones, including Conway’s ‘Game of Life’. For these (b) we prove by explicit construction that all the one-dimensional ones are representable as LG, and (c) we present and motivate the conjecture that this result extends to any number of dimensions.The tradeoff between dissipation rate and structural complexity implied by the above results have compelling implications for the thermodynamics of computation at a microscopic scale
How to turn a second-order cellular automaton into a lattice gas: a new inversion scheme
No full text"Theoretical Aspects of Cellular Automata
The Risk of Cancer Progression in Women With Gynecological Malignancies andThrombophilic Polymorphisms: A Pilot Case-Control Study.
No full textClin Appl Thromb Hemost. 2009 Oct;15(5):535-9. Epub 2008 Jun 29.
The risk of cancer progression in women with gynecological malignancies and
thrombophilic polymorphisms: a pilot case-control study.
Tormene D, Beltramello P, Perlati M, Brandolin B, Barbar S, De Toffoli G, Simioni
P.
Department of Medical and Surgical Sciences, Second Chair of Internal Medicine,
University of Padua Medical School, Padua, Italy. [email protected]
Cancer produces a hypercoagulable state, which might lead to thrombosis, and on
contrary, unprovoked venous thromboembolism might be the manifestation of an
occult cancer. In this pilot case-control study, we assessed the risk of
gynecological malignant diseases related to the presence of the factor V Leiden
and prothrombin G20210A polymorphisms. Fifty-two women underwent an operation for
gynecological malignancy and were enrolled in the study. Women who underwent an
operation for gynecological nonmalignant disease in the same days of cases were
considered as controls. The presence of factor V Leiden and prothrombin G20210A
was assessed in case and control groups. In all, 7 out of 52 cases were carriers
of the 2 polymorphisms compared with 20 out of 198 controls (odds ratio = 1.3;
95% confidence interval, 0.6-3.0). The results were also similar when the risk
was considered separately for the site of cancer. As for advanced and metastatic
malignancies, the odds ratios were 2.3 (95% confidence interval, 0.9-6.0) and 3.3
(95% confidence interval, 1.0-11), respectively, compared to noncancer patients.
When these 2 groups were compared to nonadvanced cancer group, the odds ratios
for carriers of polymorphisms were 2.7 (95%confidence interval, 0.7-11.0) and 3.9
(95%confidence interval, 0.8-18.6) for advanced cancer and metastatic
malignancies, respectively. Women with factor V Leiden or prothrombin G20210A
polymorphisms who developed gynecological malignancy might present with a higher
stage of cancer at the time of surgery. Larger case-control studies in similar
cohort of patients are needed to confirm these findings.
PMID: 18591179 [PubMed - indexed for MEDLINE
Osteoprotegerin: a pancreatic islets dysfunction and vascular injury modulator
No full textBackground. Osteoprotegerin (OPG) is a soluble glycoprotein of the tumor necrosis factor (TNF) receptor superfamily, which was initially identified as a key regulator in bone turnover. It acts as a decoy receptor for the receptor activator of nuclear factor kB ligand (RANKL) and for the TNF-related apoptosis-inducing ligand (TRAIL), counterbalancing their biological effects. OPG is produced by a wide range of tissues, including the cardiovascular system, and its levels are particularly high in aortic and renal arteries. Several studies have clearly demonstrated that the serum levels of OPG are elevated in diabetic and nondiabetic patients affected by cardiovascular diseases, and increased levels of OPG represent a risk factor for cardiovascular mortality, especially in diabetic patients. However, in spite of the reported findings, the physiopathological role of elevated serum levels of OPG in vascular biology and in pancreatic islet function are not well understood.
Aim of the study. The aims of our studies were:
Study 1. Evaluate the potential role of OPG in the pathogenesis of diabetes associated atherosclerosis.
Study 2. Investigate OPG effects on pancreatic islet function and its interaction with local pancreatic renin-angiotensin system (RAS).
Materials and Methods. Study 1.A. In vivo study: 80 apoE knockout male mice were further randomized into 4 groups (n=20) and followed for 3 months. One group of non diabetic animals received an intraperitoneal (i.p.) injection of vehicle and served as a control; another group of non-diabetic animals received every 3 weeks an i.p. injection of human recombinant OPG (OPG). The other two groups, rendered diabetic by 5 daily i.p. injections of streptozotocin (55mg/Kg/die), received injections of OPG or an equivalent volume of vehicle. At the end of the study, animals were culled, the blood was collected for biochemical analysis, and the entire aorta was excised out to study the total plaques extent and to evaluate the lesion composition and complexity of the aortic plaques. B. In vitro study: Murine vascular smooth muscle cells (VMSC) were treated with different concentrations of OPG, TGFβ and SB431542 (TGFβ- type 1 receptor inhibitor). Subsequently, cellular proliferation and pro-fibrotic markers gene expression were evaluated at different time points. OPG protein release was measured in growth media (ELISA technique).
Study 2. 40 male mice C57Bl/6J, aged 10 weeks, were randomized into 4 groups (n=10) and studied for 3 months. Group 1 received every 3 weeks an i.p. injection of vehicle and served
as a control. Group 2 received every 3 weeks an i.p. injection of OPG. Group 3 received the ACE inhibitor ramipril at the dose of 10mg/Kg/die in drinking water in co-treatment with i.p. injections of vehicle. Group 4 received ramipril in co-treatment with i.p. injections of OPG. At the end of the study, animals were culled, the blood was collected for biochemical analysis, and the pancreas was dissected out for subsequent quantitative RT-PCR measurements and immunohistochemical analysis.
Results. Study 1.A. At the end of the study, diabetic animals injected with OPG presented a significant increase in total plaques extent, with an increase of smooth muscle cells content in aortic plaques. Moreover OPG treated animals showed an increase in the collagen content in aortic media in respect to control mice. B. OPG promoted VSMC proliferation and pro-fibrotic markers gene expression. TGFβ treatment of VSMC induced a dose-dependent increase of OPG gene and protein expression, that was completed prevented by pre-treatment with the SB431542 inhibitor.
Study 2. OPG-treated animals showed increased islet monocyte-macrophage infiltration, fibrosis and apoptosis with reduction of islet function. The remodeling of islet architecture was associated with increased pancreatic expression of components of the RAS, growth factor genes (TGFβ and CTGF) and inflammatory molecules (MCP-1 and VCAM-1). Prevention of these changes with improvement of insulin secretion was observed in ramipril treated animals.
Conclusion. Study 1.A-B OPG seems to play an important pathogenetic role in the development and progression of diabetic atherosclerosis.
Study 2. Our data suggest that OPG might play an important role in promoting beta cell dysfunction and the upregulation of the local RAS represents one possible mechanism responsible for the OPG-induced beta cell dysfunction
Codes and Protocols for Distilling , controlled-, and Toffoli Gates
No full textWe present several different codes and protocols to distill , controlled-, and Toffoli (or ) gates. One construction is based on codes that generalize the triorthogonal codes, allowing any of these gates to be induced at the logical level by transversal . We present a randomized construction of generalized triorthogonal codes obtaining an asymptotic distillation efficiency . We also present a Reed-Muller based construction of these codes which obtains a worse but performs well at small sizes. Additionally, we present protocols based on checking the stabilizers of magic states at the logical level by transversal gates applied to codes; these protocols generalize the protocols of
. Several examples, including a Reed-Muller code for -to-Toffoli distillation, punctured Reed-Muller codes for -gate distillation, and some of the check based protocols, require a lower ratio of input gates to output gates than other known protocols at the given order of error correction for the given code size. In particular, we find a T-gate to Toffoli gate code with distance as well as triorthogonal codes with parameters with very low prefactors in front of the leading order error terms in those codes
Angular dependent time delay near correlation induced Cooper minima
No full textWe analyze an angular dependence of the Wigner time delay near the Cooper minimum (CM) of the sub-valent ns shell in argon, krypton and xenon. Such an angular dependence is a result of interplay between the relativistic and correlation effects. The correlation with the outermost np valence shell induces a CM in the sub-valent ns shell which is otherwise CM free. A phase difference between the two spin-orbit split ionization continua Ep 1/2 and Ep 3/2 makes the Wigner time delay angular dependent. Both these effects are accounted for within relativistic formulations of the random phase approximation and the time-dependent density functional theory. Comparison between these two approaches illustrates a very strong sensitivity of the observed effect to the computation detail, especially the account of the ground state correlation
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