Dust formation, evolution, and obscuration effects in the very high-redshift universe

The evolution of dust at redshifts z>9, and consequently the dust properties, differs greatly from that in the local universe. In contrast to the local universe, core collapse supernovae (CCSNe) are the only source of thermally-condensed dust. Because of the low initial dust-to-gas mass ratio, grain destruction rates are low, so that CCSNe are net producers of interstellar dust. Galaxies with large initial gas mass or high mass infall rate will therefore have a more rapid net rate of dust production comported to galaxies with lower gas mass, even at the same star formation rate. The dust composition is dominated by silicates, which exhibit a strong rise in the UV opacity near the Lyman break. This "silicate-UV break" may be confused with the Lyman break, resulting in a misidentification of a galaxies' photometric redshift. In this paper we demonstrate these effects by analyzing the spectral energy distribution (SED) of MACS1149-JD, a lensed galaxy at z=9.6. A potential 2mm counterpart of MACS1149-JD has been identified with GISMO. While additional observations are required to corroborate this identification, we use this possible association to illustrate the physical processes and the observational effects of dust in the very high redshift universe.Comment: Accepted for publication in ApJ Letter

Heuristics for service technician routing and scheduling problems

Die Arbeit befasst sich mit dem service technician routing and scheduling Problem. Das Problem entsteht dadurch, dass eine fixe Belegschaft von unterschiedlich ausgebildeten Technikern eine Menge von Aufträgen bearbeiten muss die unterschiedliche Fachkenntnisse erfordern. Erschwerend kommt hinzu, dass die Aufträge örtlich unterschiedlich gelegen sind und nur in bestimmten Zeitfenstern besucht werden können. Darüber hinaus kommt es vor, dass manche Aufträge zu hohe Anforderungen an einzelne Techniker stellen. Dies erfordert die Zusammengruppierung von mehreren Technikern um mit den vereinten Kenntnissen den nachgefragten Anforderungen gerecht zu werden. Grundsätzlich kann dieses Problem als eine Erweiterung des vehicle routing Problems (VRP) verstanden werden, wobei die Fahrzeuge durch die Techniker oder Teams ersetzt werden und die Kunden durch die Aufträge mit den unterschiedlichen Anforderungen. Die Herausforderung besteht nun darin, Routen zu generieren die möglichst viele Aufträge einschließen, wobei den nachgefragten Fähigkeiten und den Zeitfenstern entsprochen wird. Um das Problem zu lösen wird die sogenannte adaptive large neighborhood search Heuristik (ALNS) angewendetThe thesis deals with a real life planning challenge faced by many companies, namely the service technician routing and scheduling problem. The problem appears when a given pool of differently skilled technicians has to execute a set of tasks which have different skill requirements. Furthermore, tasks are located at different sites and their visiting is constrained by time windows. As in some cases the tasks´ requirements are too high to be met by a single technician, it may also be necessary to group some technicians together to aggregate their skills. Basically, this problem can be interpreted as an extended vehicle routing problem (VRP) in which the vehicles are replaced by the different teams or technicians, and the customers by tasks with diverse demands. The challenge is now to create routes that visit as many tasks as possible, by considering the demanded skills and the time window constraints. To tackle this problem the adaptive large neighborhood search heuristic (ALNS) was applied

Random walk of second class particles in product shock measures

We consider shock measures in a class of conserving stochastic particle systems on Z. These shock measures have a product structure with a step-like density profile and include a second class particle at the shock position. We show for the asymmetric simple exclusion process, for the exponential bricklayers' process, and for a generalized zero range process, that under certain conditions these shocks, and therefore the second class particles, perform a simple random walk. Some previous results, including random walks of product shock measures and stationary shock measures seen from a second class particle, are direct consequences of our more general theorem. Multiple shocks can also be handled easily in this framework. Similar shock structure is also found in a nonconserving model, the branching coalescing random walk, where the role of the second class particle is played by the rightmost (or leftmost) particle.Comment: Minor changes after referees' comment

The Coding and Inter-Manual Transfer of Movement Sequences

The manuscript reviews recent experiments that use inter-manual transfer and inter-manual practice paradigms to determine the coordinate system (visual–spatial or motor) used in the coding of movement sequences during physical and observational practice. The results indicated that multi-element movement sequences are more effectively coded in visual–spatial coordinates even following extended practice, while very early in practice movement sequences with only a few movement elements and relatively short durations are coded in motor coordinates. Likewise, inter-manual practice of relatively simple movement sequences show benefits of right and left limb practice that involves the same motor coordinates while the opposite is true for more complex sequences. The results suggest that the coordinate system used to code the sequence information is linked to both the task characteristics and the control processes used to produce the sequence. These findings have the potential to greatly enhance our understanding of why in some conditions participants following practice with one limb or observation of one limb practice can effectively perform the task with the contralateral limb while in other (often similar) conditions cannot

OVERVIEW OF THE RELEVANT INDICATORS OF DEFAULTED AND NON-DEFAULTED COMPANIES AND POSSIBILITIES OF IMPROVEMENT FOR THE RATING SYSTEMS USED BY THE ROMANIAN COMMERCIAL BANKS

Since the beginning of the financial and economic crises many news came to light which discussed the increasing number of non-performing loans, and the fact that as a result of the company break-downs, the bank portfolios have also gone worse and worse. In this paper our goal is to find out which internal factors influence the solvency of a company, therefore, to point out the weaknesses of the current Romanian rating systems, which as we will see, do not take into only relevant criteria when according a loan to a company. In order to conduct this study, we choose 18 indicators from several categories to predict bankruptcy. Some of the indicators mentioned above are really common in the international and the Romanian literature (e.g. ROA, ROE, ROS, assets turnover ratio), some of them are less. On a sample of 3000 Romanian companies we use the T-test statistical method to find out if an indicator is significant or not. The sample consists of companies (defaulted and non-defaulted as well) which have presented their financial statements (balance, profit and loss account between 1999 and 2008). For each company a set of 18 financial indicators was calculated, but the results obtained show that only 8 of them is significant in predicting bankruptcy: ROA, assets turnover ratio, equity/total assets, general leverage, current assets to total assets, cash to total assets, total assets and sales. In the next step, by analyzing the obligatory forms used in credit lending, we conclude which indicators are used by different Romanian commercial banks. We found that only four out of seven banks calculate all of the significant indicators identified in the first part of the paper. Finally, we made a proposal about which quantitative indicators should the banks use to minimize the credit losses and to avoid the overdue payments. In addition, we consider that the banks should pay attention to the qualitative factors as well to effectively filter out non-performing loans.corporate failure, default, risk, financial ratios, rating systems, Romania