This note addresses a problem of assigning human operators to operations in a manufacturing system. The problem involves a set of operations, a work load for each operation, and a set of human ...operators, each skilled at a subset of the operations. The task is to assign the operators to the operations so as to maximize the capacity of the system, robustly. The problem is formulated as a network flow problem with a lexicographic objective. It is then shown how to solve this problem very efficiently as a parametric sequence of network maximum flow problems, by application of the "parametric preflow" algorithm of Gallo, Grigoriadis and Tarjan.
Efforts to test Duverger’s law in the new democracies of postcommunist Europe have had mixed results. Research argues that mixed systems have an effect on the number of effective parties that is ...distinct from that of single-mandate district and proportional representation systems. Less attention has been given to the effect of other institutions on the party system, particularly strong presidents. Analyzing election results in postcommunist Europe, the authors find support for Duverger’s law after controlling for the strength of the executive. They argue that strong presidents substantially reduce the incentive for parties to seize control of the legislative agenda. Hence, the restraint that electoral systems exercise on the proliferation of parties and independent candidates is weakened. The authors find that a further consequence of strong presidents is that the incentive for majority control of committees and the legislative agenda is weakened.
Genetic aberrations are the primary events leading to carcinogenesis in various tissues and are characteristic for certain tumor types. Amplification of N-myc and deletion of 1p significantly ...correlate with poor prognosis of neuroblastoma patients. Very little informations is available on the regulation of N-myc expression by external factors. Insulin-like growth factor-II (IGF-II) has been identified as an autocrine growth factor in neuroblastoma. Four neuroblastoma cell lines were examined for their expression of IGF-II and IGF-receptor. Stimulation of neuroblastoma cells with IGF-II leads to an increased activity of the MAP-kinase Erk1, an induction of N-myc expression and an enhanced proliferation rate. In order to disrupt the signal transduction of the IGF-receptor, we inactivated the Ras-proteins in neuroblastoma cells by inhibition of the farnesyl-protein transferase by FTI-277. This inactivation prevented activation of MAP-kinase Erk1 and induction of N-myc expression by IGF-II. Inactivation of Ras by farnesyltransferase inhibitors might become a promising new approach in future treatments of neuroblastoma tumors.
Autocrine growth stimulation by IGF-II and BDNF is frequently observed in neuroblastoma. The signals of the receptors of these growth factors are transduced to the nucleus via the Ras-MAP-kinase ...pathway where they induce proliferation. Inactivation of Ras-proteins by farnesyltransferase inhibitors such as FTI-277 disrupts growth stimulation of ras-transformed cells. We investigated whether FTI-277 is also active against tumor cells with constitutively activated growth factor receptors but lacking ras-mutations.
We analyzed eight different neuroblastoma cell lines for the expression of BDNF and its receptor trkB. Two of these cell lines with a complete autocrine BDNF loop were treated with FTI-277, and the effects of Ras-inactivation on the signal transduction of BDNF were analyzed.
Treatment of neuroblastoma cells with 10 microM FTI-277 for 4 days reduced the amount of membrane-bound Ras-protein to almost 50%. Activation of MAP-kinase, induction of N-myc expression, and proliferation were clearly reduced in the treated cells. In addition, we observed some cytotoxic effects of FTI-277 accompanied by morphological changes of the neuroblastoma cells and a delayed induction of apoptosis.
Farnesyltransferase inhibitors are active against neuroblastoma cells but the mechanism of action is not limited to inactivation of Ras. Further investigations on the targets of FTI-277 are recommended.
The Transiting Exoplanet Survey Satellite (TESS) provides a continuous suite of new planet candidates that need confirmation and precise mass determination from ground-based observatories. This is ...the case for the G-type star TOI-1710, which is known to host a transiting sub-Saturn planet (\(\mathrm{M_p}=\)28.3\(\pm\)4.7\(\mathrm{M}_\oplus\)) in a long-period orbit (P=24.28\,d). Here we combine archival SOPHIE and new and archival HARPS-N radial velocity data with newly available TESS data to refine the planetary parameters of the system and derive a new mass measurement for the transiting planet, taking into account the impact of the stellar activity on the mass measurement. We report for TOI-1710b a radius of $\mathrm{R_p}$$=\(5.15\)\pm\(0.12\)\mathrm{R}_\oplus\(, a mass of \)\mathrm{M_p}$$=\(18.4\)\pm\(4.5\)\mathrm{M}_\oplus\(, and a mean bulk density of \)\rho_{\rm p}$$=\(0.73\)\pm\(0.18\)\mathrm{g \, cm^{-3}}\(, which are consistent at 1.2\)\sigma\(, 1.5\)\sigma\(, and 0.7\)\sigma\(, respectively, with previous measurements. Although there is not a significant difference in the final mass measurement, we needed to add a Gaussian process component to successfully fit the radial velocity dataset. This work illustrates that adding more measurements does not necessarily imply a better mass determination in terms of precision, even though they contribute to increasing our full understanding of the system. Furthermore, TOI-1710b joins an intriguing class of planets with radii in the range 4-8 \)\mathrm{R}_\oplus$ that have no counterparts in the Solar System. A large gaseous envelope and a bright host star make TOI-1710b a very suitable candidate for follow-up atmospheric characterization.
This note addresses a problem of assigning human operators to operations in a manufacturing system. The problem involves a set of operations, a work load for each operation, and a set of human ...operators, each skilled at a subset of the operations. The task is to assign the operators to the operations so as to maximize the capacity of the system, robustly. The problem is formulated as a network flow problem with a lexicographic objective. It is then shown how to solve this problem very efficiently as a parametric sequence of network maximum flow problems, by application of the "parametric preflow" algorithm of Gallo, Grigoriadis and Tarjan.
PDF
