Disentangling the physical reality of star cluster candidates projected towards the inner disc of the Large Magellanic Cloud

We have used Washington photometry for 90 star cluster candidates of small angular size -typically ~ 11" in radius- distributed within nine selected regions in the inner disc of the Large Magellanic Cloud (LMC) to disentangle whether they are genuine physical system, and to estimate the ages for the confirmed clusters. In order to avoid a misleading interpretation of the cluster colour-magnitude diagrams (CMDs), we applied a subtraction procedure to statistically clean them from field star contamination. Out of the 90 candidate clusters studied, 61 of them resulted to be genuine physical systems, whereas the remaining ones were classified as possible non- clusters since either their CMDs and/or the distribution of stars in the respective fields do not resemble those of stellar aggregates. We statistically show that ~ (13 +- 6)% of the catalogued clusters in the inner disc could be possible non-clusters, independently of their deprojected distances. We derived the ages for the confirmed clusters from the fit of theoretical isochrones to the cleaned cluster CMDs. The derived ages resulted to be in the age range 7.8 < log(t) < 9.2. Finally, we built cluster frequencies for the different studied regions and found that there exists some spatial variation of the LMC CF throughout the inner disc. Particularly, the innermost field contains a handful of clusters older than ~ 2 Gyr, while the wider spread between different CFs has taken place during the most recent 50 Myr of the galaxy lifetime.Comment: MNRAS, accepte

L2L^2 orbital stability of Dirac solitons in the massive Thirring model

We prove $L^2$ orbital stability of Dirac solitons in the massive Thirring model. Our analysis uses local well posedness of the massive Thirring model in $L^2$, conservation of the charge functional, and the auto--B\"{a}cklund transformation. The latter transformation exists because the massive Thirring model is integrable via the inverse scattering transform method

Cyclic Permutations in Kazama-Suzuki String Models

Moddings by cyclic permutation symmetries are performed in 4-dimensional strings, built up from N=2 coset models of the type $CP_m=SU(m+1)/SU(m)\times U(1)$. For some exemplifying cases, the massless chiral and antichiral states of $E_6$ are computed. The extent of the equivalence between different conformal invariant theories which possess equal chiral rings is analyzed.Comment: 26 pages, LaTex fil

Price formation, nominal anchors, and stabilization policies in Hungary : an empirical analysis

The authors empirically explore the inflationary process in Hungary. Using monthly data, they provide econometric estimates of the determinants of inflation for 1990-92. Empirical estimates of price equations - both consumer price index (CPI) and producer price index (PPI) - show the exchange rate's quantitative importance and statistical significance in price formation in Hungary during the period of intensified reform as the economy became more open to international trade in both inputs and final goods. Their estimates show that the money supply affects consumer and producer prices with several lags; its impact on prices is small in the short run. Nominal wages have a more significant effect on the CPI than on the PPI. The authors present policy simulations of alternative rules for the exchange rate and the money supply and their effect on the rate of inflation and the level of the real exchange rate. They find that a rule of fixing the exchange rate entails a lower level of CPI inflation - 5 percentage points less of CPI inflation a year - than if the rule is based only on reducing the rate of money growth (to 1 percent a month). But a fixed exchange rate policy is associated with greater appreciation of the real exchange rate than is the policy of money-based disinflation - nearly 4 percentage points more real appreciation a year. A PPI-based exchange rate rule stabilizes the real exchange rate at the cost of a substantial acceleration in inflation. These exercises illustate the nature and magnitude of the tradeoffs between faster disinflation and the level of external competitiveness in an open economy such as Hungary that uses the exchange rate as a nominal anchor in disinflation.Economic Theory&Research,Environmental Economics&Policies,Economic Stabilization,Macroeconomic Management,Markets and Market Access

Vital dye labelling of Xenopus laevis trunk neural crest reveals multipotency and novel pathways of migration

Although the Xenopus embryo has served as an important model system for both molecular and cellular studies of vertebrate development, comparatively little is known about its neural crest. Here, we take advantage of the ease of manipulation and relative transparency of Xenopus laevis embryos to follow neural crest cell migration and differentiation in living embryos. We use two techniques to study the lineage and migratory patterns of frog neural crest cells: (1) injections of DiI or lysinated rhodamine dextran (LRD) into small populations of neural crest cells to follow movement and (2) injections of LRD into single cells to follow cell lineage. By using non-invasive approaches that allow observations in living embryos and control of the time and position of labelling, we have been able to expand upon the results of previous grafting experiments. Migration and differentiation of the labelled cells were observed over time in individual living embryos, and later in sections to determine precise position and morphology. Derivatives populated by the neural crest are the fins, pigment stripes, spinal ganglia, adrenal medulla, pronephric duct, enteric nuclei and the posterior portion of the dorsal aorta. In the rostral to mid-trunk levels, most neural crest cells migrate along two paths: a dorsal pathway into the fin, followed by presumptive fin cells, and a ventral pathway along the neural tube and notochord, followed by presumptive pigment, sensory ganglion, sympathetic ganglion and adrenal medullary cells. In the caudal trunk, two additional paths were noted. One group of cells moves circumferentially within the fin, in an arc from dorsal to ventral; another progresses ventrally to the anus and subsequently populates the ventral fin. By labelling individual precursor cells, we find that neural tube and neural crest cells often share a common precursor. The majority of clones contain labelled progeny cells in the dorsal fin. The remainder have progeny in multiple derivatives including spinal ganglion cells, pigment cells, enteric cells, fin cells and/or neural tube cells in all combinations, suggesting that many premigratory Xenopus neural crest precursors are multipotent

PPM/NAR 8.4-GHz noise temperature statistics for DSN 64-meter antennas, 1982-1984

From August 1982 through November 1984, X-band downlink (8.4-GHz) system noise temperature measurements were made on the DSN 64-m antennas during tracking periods. Statistics of these noise temperature values are needed by the DSN and by spacecraft mission planners to assess antenna, receiving, and telemetry system needs, present performance, and future performance. These measurements were made using the DSN Mark III precision power monitor noise-adding radiometers located at each station. It is found that for DSS 43 and DSS 63, at the 90% cumulative distribution level, equivalent zenith noise temperature values fall between those presented in the earlier (1977) and present (1983) versions of DSN/Flight Project design documents. Noise temperatures measured for DSS 14 (Goldstone) are higher than those given in existing design documents and this disagreement will be investigated as a diagnostic of possible PPM or receiving system performance problems

Critical connectedness of thin arithmetical discrete planes

An arithmetical discrete plane is said to have critical connecting thickness if its thickness is equal to the infimum of the set of values that preserve its $2$-connectedness. This infimum thickness can be computed thanks to the fully subtractive algorithm. This multidimensional continued fraction algorithm consists, in its linear form, in subtracting the smallest entry to the other ones. We provide a characterization of the discrete planes with critical thickness that have zero intercept and that are $2$-connected. Our tools rely on the notion of dual substitution which is a geometric version of the usual notion of substitution acting on words. We associate with the fully subtractive algorithm a set of substitutions whose incidence matrix is provided by the matrices of the algorithm, and prove that their geometric counterparts generate arithmetic discrete planes.Comment: 18 pages, v2 includes several corrections and is a long version of the DGCI extended abstrac