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For inspection purposes first ideas of an in-pipe robot are presented. The idea of a rover with respect to the environmental conditions, as well as details of structure, actuation, measurement and control concepts is discussed in this document. It should be able to navigate through rather narrow and buckled drainage pipes with diameters not much larger than the robot itself, so the design is aiming for a most compact and potentially self-disassembling solution necessary for cases of stuck robots.

We present an algorithm for solving bilevel linear programs that uses simplex pivots on an expanded tableau. The algorithm uses the relationship between multiple objective linear programs and bilevel linear programs along with results for minimizing a linear objective over the efficient set for a multiple objective problem. Results in multiple objective programming needed are presented. We report computational experience demonstrating that this approach is more effective than a standard branch-and-bound algorithm when the number of leader variables is small.

The duality theory of geometric programming as developed by Duffin, Peterson and Zener is based on abstract properties shared by certain classical inequalities, such as Cauchy's arithmetic-geometric mean inequality and Holder's inequality. Inequalities with these abstract properties have been termed 'geometric inequalities.' In this paper we establish a new geometric inequality and use it to extend the 'refined duality theory' for 'posynomial' geometric programs. This extended duality theory treats both 'quadratically-constrained quadratic programs' and 'l sub p-constrained l sub p-approximation (regression) problems' through a rather novel and unified formulation of these two classes of programs. This work generalizes some of the work of others on linearly-constrained quadratic programs, and provides to the best of our knowledge the first explicit formulation of duality for constrained approximation problems. Other people have developed duality theories for a larger class of programs, namely all convex programs, but those theories (when applied to the programs considered here) are not nearly as strong as the theory developed here. This theory has virtually all of the desirable features of its analog for posynomial programs, and its proof provides useful computational procedures. (Author)

We perform a complete analysis of isospin breaking in K -> Pi Pi amplitudes in chiral perturbation theory, including both strong isospin violation and electromagnetic corrections to next-to-leading order in the low-energy expansion. The unknown chiral couplings are estimated at leading order in the 1/N_c expansion. We study the impact of isospin breaking on CP conserving amplitudes and rescattering phases. In particular, we extract the effective couplings g_8 and g_27 from a fit to K -> Pi Pi branching ratios, finding small deviations from the isospin-limit case. The ratio Re(A_0)/Re(A_2) measuring the Delta I=1/2 enhancement is found to decrese from 22.1 +/- 0.1 in the isospin limit to 20.3 +/- 0.5 in the presence of isospin breaking. We also analyse the effect of isospin violation on the CP violation parameter epsilon-prime, finding a destructive interference between three different sources of isospin violation. Within the uncertainties of large-N_c estimates for the low-energy constants, the isospin violating correction for epsilon-prime is below 15%.

The status of chiral perturbation theory in the meson sector is illustrated with several topical examples. The longtime discrepancy between theory and experiment for the charged pion polarizabilities has now been resolved in favour of the chiral SU(2) result to next-to-next-to-leading order. For chiral SU(3), the main obstacles are the large number of badly known coupling constants (LECs) and the lack of convergence of the low-energy expansion in many cases of interest. I describe a new global fit of the LECs in the strong sector that leads to a prediction of the CKM matrix element $V_{us}$ in agreement with the latest lattice determinations. The slow convergence of the chiral series is particularly acute in transitions with strong final-state interactions calling for dispersive treatments. The status of dispersive approaches is reviewed for $K_{\ell 4}$ decays and for $\eta -> 3 \pi$ decays where precise measurements of Dalitz plot distributions have recently become available., Comment: 18 pages, to appear in Proc. of 8th Int. Workshop on Chiral Dynamics, Pisa, Italy, 2015

We review the status of the coupling constants of chiral Lagrangians in the meson sector, the so-called low-energy constants (LECs). Special emphasis is put on the chiral $SU(2)$ and $SU(3)$ Lagrangians for the strong interactions of light mesons. The theoretical and experimental input for determining the corresponding LECs is discussed. In the two-flavour sector, we review the knowledge of the $O(p^4)$ LECs from both continuum fits and lattice QCD analyses. For chiral $SU(3)$, NNLO effects play a much bigger role. Our main new results are fits of the LECs $L_i$ both at NLO and NNLO, making extensive use of the available knowledge of NNLO LECs. We compare our results with available lattice determinations. Resonance saturation of LECs and the convergence of chiral $SU(3)$ to NNLO are discussed. We also review the status of predictions for the LECs of chiral Lagrangians with dynamical photons and leptons., 36 pages, prepared for Annual Review of Nuclear and Particle Science, typos corrected, reference added, results unchanged

We update the theoretical analysis of the CP-violating asymmetry in the decay K_L -> pi+ pi- e+ e-, relying on chiral perturbation theory and on the most recent phenomenological information. With the experimentally determined magnetic amplitude and branching ratio as input, the asymmetry can be calculated with good accuracy. The theoretical interpretation of the sign of the asymmetry is discussed.

We determine the full structure of the leading (double-pole) divergences of O(p^6) in the meson sector of chiral perturbation theory. The field theoretic basis for this calculation is described. We then use an extension of this result to determine the p^6 contributions containing double chiral logarithms (L^2), single logarithms times p^4 constants (L x L_i^r) and products of two p^4 constants (L_i^r x L_j^r) for F_\pi, F_K/F_\pi, K_{l3} and K_{e4} form factors. Numerical results are presented for these quantities., Comment: Latex, 13 pages, 1 figure

We construct large-N_c motivated approximate chiral SU(3) amplitudes of next-to-next-to-leading order. The amplitudes are independent of the renormalization scale. Fitting lattice data with those amplitudes allows for the extraction of chiral coupling constants with the correct scale dependence. The differences between approximate and full amplitudes are required to be at most of the order of N^3LO contributions numerically. Applying the approximate expressions to recent lattice data for meson decay constants, we determine several chiral couplings with good precision. In particular, we obtain a value for F_0, the meson decay constant in the chiral SU(3) limit, that is more precise than all presently available determinations.

We present technical details of the evaluation of the elastic pi-pi scattering amplitude to two loops in chiral perturbation theory. In particular, we elaborate on the renormalization procedure at the two-loop order and on the evaluation of the relevant Feynman diagrams that can all be expressed in terms of elementary functions. For the sake of clarity, we discuss these matters both in the N-component $\phi^4$ theory (in its symmetric phase) and in chiral perturbation theory. Estimates for the relevant low-energy constants of $O(p^6)$ are presented. Threshold parameters and phase shifts are then calculated for two sets of $O(p^4)$ coupling constants and compared with experiment. We comment on the extraction of threshold parameters from phase shift data., Comment: LaTeX, uses epsf.sty, 10 figures, 52 pages

After a brief introduction to chiral perturbation theory, the effective field theory of the standard model at low energies, two recent applications are reviewed: elastic pion-pion scattering to two-loop accuracy and the complete renormalized pion-nucleon Lagrangian to $O(p^3)$ in the chiral expansion., Comment: 14 pages, Latex, 1 figure in uuencoded postscript file embedded with epsfig.sty. To appear in Proc. of Int. School of Nuclear Physics, Erice, Sept. 1995, Progr. Part. Nucl. Phys., vol. 36

Chiral perturbation theory is the effective field theory of the Standard Model at low energies. After a short introduction and overview, I discuss three topics where the chiral approach leads to a deeper understanding of low-energy hadron physics: radiative kaon decays, carbogenesis in stellar nucleosynthesis and the interplay of chiral perturbation theory and lattice QCD., Comment: 16 pages, 7 figures, to appear in Proceedings of Hadron Structure '13, July 2013, Tatranske Matliare, Slovakia

The problem (P) of optimizing a linear functiond T x over the efficient set for a multiple-objective linear program (M) is difficult because the efficient set is typically nonconvex. Given the objective function directiond and the set of domination directionsD, ifd T π≧0 for all nonzero π∈D, then a technique for finding an optimal solution of (P) is presented in Section 2. Otherwise, given a current efficient point $$\hat x$$ , if there is no adjacent efficient edge yielding an increase ind T x, then a cutting plane $$d^T x = d^T \hat x$$ is used to obtain a multiple-objective linear program ( $$\bar M$$ ) with a reduced feasible set and an efficient set $$\bar E$$ . To find a better efficient point, we solve the problem (Ii) of maximizingc x over the reduced feasible set in ( $$\bar M$$ ) sequentially fori. If there is a $$x^i \in \bar E$$ that is an optimal solution of (Ii) for somei and $$d^T x^i > d^T \hat x$$ , then we can choosex i as a current efficient point. Pivoting on the reduced feasible set allows us to find a better efficient point or to show that the current efficient point $$\hat x$$ is optimal for (P). Two algorithms for solving (P) in a finite sequence of pivots are presented along with a numerical example.

6 páginas, 2 figuras., We discuss the rare decay KL → π0γγ. Although the recently measured 2γ-invariant-mass distribution is in quite good agreement with the lowest-order chiral perturbation theory prediction, there seems to be a discrepancy with the calculated branching ratio. We extend the previous computations to next-to-leading order, O(p6). The two dominant mechanism at this order are emphasized: the two-poin intermediate state and vector meson exchange., The work of A.P. has been supported in part by CICYT, Spain, under grant AEN90-0040. The work of A.G.C. was supported in part by the Department of Energy under contract #DE-FG02-91 ER40676 and by the Texas National Research Laboratory grant #RGFY92B6.

We consider the weak interactions of the octet of pseudoscalar mesons with meson resonances with spin 0,1 to lowest order in the derivative expansion. We determine the resonance contributions to the O( p 4 ) weak coupling constants. In general, the resonance contributions imply only relations between these constants. If additional assumptions such as factorization or weak deformation are imposed, a more detailed comparison with experiment becomes possible. In contrast to the strong sector, available data do not suggest that all the weak couplings of the p 4 -lagrangian are dominated by resonance exchange in the factorization approximation. We also give a treatment of singlet external fields.

While significant progress has been made, analytic research on principal-agent problems that seek closed-form solutions faces limitations due to tractability issues that arise because of the mathematical complexity of the problem. The principal must maximize expected utility subject to the agent’s participation and incentive compatibility constraints. Linearity of performance measures is often assumed and the Linear, Exponential, Normal (LEN) model is often used to deal with this complexity. These assumptions may be too restrictive for researchers to explore the variety of relationships between compensation contracts offered by the principal and the effort of the agent. In this paper we show how to numerically solve principal-agent problems with nonlinear contracts. In our procedure, we deal directly with the agent’s incentive compatibility constraint. We illustrate our solution procedure with numerical examples and use optimization methods to make the problem tractable without using the simplifying assumptions of a LEN model. We also show that using linear contracts to approximate nonlinear contracts leads to solutions that are far from the optimal solutions obtained using nonlinear contracts. A principal-agent problem is a special instance of a bilevel nonlinear programming problem. We show how to solve principal-agent problems by solving bilevel programming problems using the ellipsoid algorithm. The approach we present can give researchers new insights into the relationships between nonlinear compensation schemes and employee effort.

GE Capital provides credit card services for a consumer credit business exceeding $12 billion in total outstanding dollars. Its objective is to optimally manage delinquency by improving the allocation of limited collection resources to maximize net collections over multiple billing periods. We developed a probabilistic account flow model and statistically designed programs to provide accurate data on collection resource performance. A linear programming formulation produces optimal resource allocations that have been implemented across the business. The PAYMENT system has permanently changed the way GE Capital manages delinquent consumer credit, reduced annual losses by approximately $37 million, and improved customer goodwill.

Elastic pion-pion and pion-nucleon scattering are reviewed in the context of chiral perturbation theory. Theoretical results from systematic low-energy expansions to O(p^6) for pion-pion and to O(p^3) for pion-nucleon scattering are compared with experimental data. Possible future developments are outlined.

The phenomenological and theoretical status of the low-energy parameters of effective chiral Lagrangians is reviewed.

A survey is made of semileptonic and nonleptonic kaon decays in the framework of chiral perturbation theory. The emphasis is on what has been done rather than how it was done. The theoretical predictions are compared with available experimental results., 15 pages, Latex, 4 figures embedded with epsfig.sty. To appear in Proc. of Workshop on Heavy Quarks at Fixed Target, St. Goar, Germany, Oct. 1996

A successful unified pharmacophore/receptor model which has guided the synthesis of subtype selective compounds is reviewed in light of recent developments both in ligand synthesis and structural studies of the binding site itself. The evaluation of experimental data in combination with a comparative model of the alpha1beta2gamma2 GABA(A) receptor leads to an orientation of the pharmacophore model within the Bz BS. Results not only are important for the rational design of selective ligands, but also for the identification and evaluation of possible roles which specific residues may have within the benzodiazepine binding pocket.

Draft version of an article prepared for the Encyclopedia of Mathematical Physics, Elsevier, to appear in 2006.

Modulators of ion channels and drug design in tumor therapy are the focus of this report.

On the basis of a next-to-leading-order calculation in chiral perturbation theory, the first complete analysis of isospin breaking for direct CP violation in K0--2 pi decays is performed. We find a destructive interference between three different sources of isospin violation in the CP violation parameter epsilon'. Within the uncertainties of large-N(c) estimates for the low-energy constants, the isospin violating correction for epsilon' is below 15%.

We update the theoretical analysis of the CP-violating asymmetry in the decay KL → π+π- e+ e-, relying on chiral perturbation theory and on the most recent phenomenological information. With the experimentally determined magnetic amplitude and branching ratio as input, the asymmetry can be calculated with good accuracy. The theoretical interpretation of the sign of the asymmetry is discussed.

Following our ongoing studies on structure-activity relationship studies of propafenone-type modulators of multidrug resistance, we performed both a Free-Wilson analysis and a combined Hansch/Free-Wilson analysis on a set of 48 compounds using artificial neural networks (ANN). In comparison to classical multiple linear regression (MLR) analysis, the ANN showed equal or even slightly better predictive power in leave one out cross validation procedures and was remarkably superior when performing a leave 8 out cross validation. Additionally, it was possible to train a network using only 14 compounds and to properly predict the MDR-modulating activity of the remaining 34 compounds. In this case, the MLR analysis completely failed due to insufficient number of cases. Attempts to extract informations on which input descriptors are important using a genetic input selection algorithm failed. Best results were obtained using those descriptors which showed highest statistical significance in MLR analyses.

The presence of a nitrogen atom, charged at physiological pH, has frequently been considered to be a hallmark of P-glycoprotein (PGP) inhibitors, although certain steroids, such as progesterone, lack a nitrogen atom and still are active modulators of PGP. The present study was aimed at investigating the role the nitrogen atom plays in the activity of PGP inhibitors. Propafenone-related amines, anilines, and amides that cover a broad range of pK(a) values, as well as an ester, were synthesized and tested for multidrug resistance-reverting activity. The sum of the hydrogen bond acceptor strengths was calculated and correlated with EC(50) values for PGP inhibition. For the complete set of 12 compounds, an excellent correlation between these two parameters was found; this included the ester GP570, which lacks a nitrogen atom but contains the strong hydrogen bond-accepting ester unit. The interaction of the nitrogen atom with PGP therefore is nonional and is determined by the sum of the hydrogen acceptor strengths of the region. The high predictivity of the obtained model is demonstrated in a leave-one-out cross-validation procedure.

We employ notions familiar from supersymmetry for constructing the one-loop functional of general quantum field theories with bosons and fermions (spin < 1). To demonstrate the advantages of such an approach for calculating one-loop divergences, we analyse a simple Yukawa theory with two different versions of a super-heat-kernel expansion. These methods also simplify the calculation of one-loop divergences for non-renormalizable meson--baryon Lagrangians occurring in chiral perturbation theory., 11 pages, Latex, 1 figure embedded

A series of 5-hydroxy and 5-benzyloxy analogs of the antiarrhythmic and multidrug resistance (MDR) modulating drug propafenone was synthesized and the MDR-modulating activity of the compounds was evaluated using a daunomycin efflux assay system. The key step of the synthesis is the selective reduction of the double bond in 1 without cleavage of the benzyl group thus leading to the phenol 3. Alkylation with epichlorohydrine followed by nucleophilic epoxide ring opening gave the benzylated target compounds 5a-d. Subsequent cleavage of the benzyl group gave the 5-hydroxy analogs 6a-d. Structure activity relationship studies showed, that the 5-hydroxy derivates 6a-d fit the log P/log potency correlation line previously established for a series of propafenone analogs. In contrast, all four 5-benzyloxy analogs 5a-d showed almost identical EC50 values, independent of their log P value.

The basic pharmacological evaluation of five analogues of propafenone was the aim of the present paper. Antiarrhythmic activity of the compounds at 10(-5) mol.kg-1 was established in guinea-pigs using experimental arrhythmias induced by ouabain and aconitine. The beta-adrenolytic efficiency of the compounds was studied in the isolated spontaneously beating guinea-pig atria and expressed as pA2 values against isoprenaline tachycardia. All of the compounds studied were local-anaesthetically active and their indexes of efficiency were 1-5 fold higher in comparison with the standards cocaine and procaine. The acute toxicity of the compounds was within acceptable limits.

We present a complete analysis of K->3πγ decays to O(p^4) in the low-energy expansion of the Standard Model. We employ the notion of "generalized bremsstrahlung" to take full advantage of expermental information on the corresponding non-radiative K->3π decays.

The sodium channel blocker propafenone and a series of analogs have been identified as effective modulators of P-glyco-protein-mediated multidrug resistance in human tumor cells. A series of closely related structural homologues showed a highly significant correlation between lipophilicity and pharmacological effect. Reduction of the carbonyl group as well as conversion to a methylether led to a remarkable decrease in activity, whereby lipophilicity lost its predictive character as the main determinant for modulator potency. Similarly, the relative positioning of the acyl- and propanolamine side chains also influences activity, so the distance between carbonyl group and nitrogen atom seems important.

Inotropic, chronotropic and beta-adrenoceptor blocking activities of the newly synthetized propafenone derivatives 1-(2-(3-diethylamino-2-hydroxypropoxy)phenyl-3-phenyl-1-propanone hydrochloride (AM 03), 1-(2-(2-hydroxy-3-(1-piperidyl)propoxy)phenyl)-3-phenyl-1-propanone hydrochloride (AM 05), N,N-dimethyl-N-(2-hydroxy-3-(2-(3- phenylpropionyl)phenoxy)propyl)-propylammonium iodide (TH 41), N,N- diethyl-N-(2-hydroxy-3-(2-(3-phenylpropionyl)phenoxy)propyl)-methylammon ium iodide (AM 07), and N,N-diiso-propyl-N-(2-hydroxy-3-(2-(3-phenylpropionyl)phenoxy)prop yl)- methylammonium iodide (AM 09) studied in isolated, electrically stimulated papillary muscles and spontaneously beating right atria of guinea pigs. In comparison with propafenone the tertiary amines AM 03 and AM 05 showed a higher negative inotropic potency, while the quarternary amines TH 41, AM 07 and AM 09 were less effective. With regard to their negative chronotropic action, AM 03 and AM 05 were more and TH 41, AM 07 and AM 09 less potent than the parent drug. In contrast to propafenone none of its derivatives exerted beta-adrenoceptor blockade at the concentrations studied.

The benzofuranethanamines 3a and 3b were synthesized and pharmacologically tested to investigate structure-activity relationships with antiarrhythmic compounds. The key-step in the synthesis was the chemoselective reduction of the chloroacetyl-dihydrobenzofurane 5 to chloroethylbenzofurane 9 using triethylsilane/BF3.Et2O. Results of a series of further attempts to reduce 5 are also described. Pharmacological investigations on isolated guinea pig heart muscle preparations showed that 3a exhibits similar negative inotropic and negative chronotropic action in comparison to propafenone and the conformationally restricted benzofurane 1a. In contrast to these substances, however, 3a shows no beta 1-adrenoreceptor blocking activity.

Resistance of tumor cells to a wide variety of cytotoxic agents represents a major problem in cancer therapy. In most cases, the cross resistance profile has been shown to be accompanied by a decrease in drug accumulation in the resistant cells. At present it seems to be widely accepted that this decrease in intracellular drug levels is due to active efflux of these drugs caused by P-glycoprotein (PGP). Within the past decade, several substances have been identified as being capable of inhibiting the active drug efflux caused by P-glycoprotein. Although many excellent reviews on the phenomenon of multidrug resistance (MDR) have been published, little is known about SAR (Structure-Activity-Relationship)- or QSAR (Quantitative-Structure-Activity-Relationship)-studies of modulators of MDR. The aim of this article is to review first results in this field.

The hadronic sector of the standard model at low energies is described by a non--decoupling effective field theory, chiral perturbation theory. An introduction is given to the construction of effective chiral Lagrangians, both in the purely mesonic sector and with inclusion of baryons. The connection between the relativistic formulation and the heavy baryon approach to chiral perturbation theory with baryons is reviewed., Lectures given at the 6th Indian-Summer School on Intermediate Energy Physics, Prague, Aug. 1993, Latex, 26 pages (with a4.sty), UWThPh-1993-31

32 páginas, 3 figuras, 4 tablas.-- El PDF es el artículo publicado en el CERN en Junio de 1993., An investigation is performed of all non-leptonic kaon decays sensitive to the chiral anomaly. Within the framework of chiral perturbation theory, there are two classes of anomalous amplitudes at O(p4): reducible and direct contributions. Only radiative transitions are affected by the anomaly. The phenomenology of the decays KL → π+π−γ and K+ → π+π0γ is studied in detail. Including the dominant contributions of O(p6), the experimentally observed dependence of he direct emission amplitude for KL → π+π−γ on the photon energy can be understood. A survey is made of the rare “anomalous” decays K → ππγγ and K → 3πγ (γ), including some numerical estimates., Work supported in part by Fonds zur Förderung der wissenschaftlichen Forschung (Austria), project P08485-TEC, P09505-PHY (EURODAPHNE Collaboration) and by CICYT (Spain), grant AEN9O-0040.