Single and Multi-Dimensional Optimal Auctions - A Network Approach

This paper highlights connections between the discrete and continuous approaches to optimal auction design with single and multi-dimensional types. We provide an interpretaion of an optimal auction design problem in terms of a linear program that is an instance of a parametric shortest path problem on a lattice. We also solve some cases explicitly in the discrete framework.Auctions, Networks, Linear Programming

Do Hot Hands Exist Among Hedge Fund Managers? An Empirical Evaluation

We examine whether hot hands exist among hedge fund managers. In measuring performance persistence, we use hedge fund style benchmarks. This allows us to identify managers with valuable skills, and also to control for option-like features inherent in returns from hedge fund strategies. We take into account the possibility that reported asset values may be based on stale prices. We develop a statistical model that relates a hedge fund’s performance to its decision to liquidate or close in order to infer the performance of a hedge fund that left the database. While we find significant performance persistence among superior funds we find little evidence of persistence among inferior funds.

Capturing Hedge Fund Risk Factor Exposures: Hedge Fund Return Replication with ETFs

We develop a new factor selection methodology of spanning the space of hedge fund risk factors with all available exchange traded funds (ETFs). We demonstrate the efficacy of the methodology with out-of-sample individual hedge fund return replication by ETF clone portfolios. This is consistent with our interpretation of ETF returns as proxies to risk factors driving hedge fund returns. We further consider portfolios of “cloneable” and “noncloneable” hedge funds, defined as top and bottom in-sample R2 matches, and demonstrate that our ETF clone portfolios slightly outperform cloneable hedge funds out of sample

Постмиграционные общества: экономика, политика, культура

To understand the depth of transformations in all spheres of society generated by migration, new terminology is needed. The notion of "postmigrant societies" implies that the distinction between local and migrant population loses its relevance in certain social spheres. According to the familiar epistemological framework, societies are presented as consisting of "local population" on the one hand, and "migrant population" on the other. This understanding, however, is becoming obsolete. First, it does not reflect the fact that the phenomenon of spatial mobility is embedded in the social structure. A significant part of the so-called local population is itself included in migration processes. People who are considered to be part of the "autochthonous population" are in fact migrants themselves due to different circumstances (contract work, long-term stay in another country due to studies, involvement in joint business projects, participation in international scientific teams, availability of real estate abroad, etc.). At the same time, those people who are regarded as "migrants" by common sense can be well integrated into the social institutions of their new homeland. Second, the traditional epistemological framework does not reflect contemporary demographic trends. It is unable to capture two points: (a) population rotation within the framework of circular/pendulum migration; (b) qualitative change in the urban population of industrialized countries

Reactive trityl derivatives: stabilised carbocation mass-tags for life sciences applications

The rational design of novel triarylmethyl (trityl)-based mass tags (MT) for mass-spectrometric (MS) applications is described. We propose a "pKR+ rule" to correlate the stability of trityl carbocations with their MS performance: trityls with higher pKR+ values ionise and desorb better. Trityl blocks were synthesised that have high pKR+ values and are stable in conditions of MS analysis; these MTs can be ionised by matrix as well as irradiation with a 337 nm nitrogen laser. 13C-Labelled tags were prepared for MS quantitation applications. Moreover, the tags were equipped with a variety of functional groups allowing conjugation with different functionalities within (bio)molecules to enhance the MS characteristics of the latter. The MS behaviour of model polycationic trityl compounds with and without the matrix was studied to reveal that poly-trityl clusters are always singly charged under the (MA)LDI-TOF conditions. Several peptide-trityl conjugates were prepared and comparisons revealed a beneficial effect of trityl tags on the conjugate detection in MS. Trityl compounds containing para-methoxy- and dimethylamine groups, as well as a xanthene fragment, showed considerable enhancement in MS detection of model peptides; thus they are promising tools for proteomic applications. Dimethoxytrityl derivatives allow one to distinguish between Arg- and Lys-containing peptides. Maleimido trityl derivatives are suitable for the efficient derivatisation of thiol-containing peptides in pyridine

Reconstruction of Radio Signals from Air-Showers with Autoencoder

The Tunka Radio Extension (Tunka-Rex) is a digital antennaarray (63 antennas distributed over≈1 km2) co-located with the TAIGAobservatory in Eastern Siberia. Tunka-Rex measures radio emission ofair-showers induced by ultra-high energy cosmic rays in the frequencyband of 30-80 MHz. Air-shower signal is a short (tens of nanoseconds)broadband pulse. Using time positions and amplitudes of these pulses,we reconstruct parameters of air showers and primary cosmic rays. Theamplitudes of low-energy event (E<1017eV) cannot be used for suc-cesful reconstruction due to the domination of background. To lower theenergy threshold of the detection and increase the efficiency, we use au-toencoder neural network which removes noise from the measured data.This work describes our approach to denoising raw data and furtherreconstruction of air-shower parameters. We also present results of thelow-energy events reconstruction with autoencoder

Rationale for BepiColombo Studies of Mercury's Surface and Composition

BepiColombo has a larger and in many ways more capable suite of instruments relevant for determination of the topographic, physical, chemical and mineralogical properties of Mercury's surface than the suite carried by NASA's MESSENGER spacecraft. Moreover, BepiColombo's data rate is substantially higher. This equips it to confirm, elaborate upon, and go beyond many of MESSENGER's remarkable achievements. Furthermore, the geometry of BepiColombo's orbital science campaign, beginning in 2026, will enable it to make uniformly resolved observations of both northern and southern hemispheres. This will offer more detailed and complete imaging and topographic mapping, element mapping with better sensitivity and improved spatial resolution, and totally new mineralogical mapping. We discuss MESSENGER data in the context of preparing for BepiColombo, and describe the contributions that we expect BepiColombo to make towards increased knowledge and understanding of Mercury's surface and its composition. Much current work, including analysis of analogue materials, is directed towards better preparing ourselves to understand what BepiColombo might reveal. Some of MESSENGER's more remarkable observations were obtained under unique or extreme conditions. BepiColombo should be able to confirm the validity of these observations and reveal the extent to which they are representative of the planet as a whole. It will also make new observations to clarify geological processes governing and reflecting crustal origin and evolution. We anticipate that the insights gained into Mercury's geological history and its current space weathering environment will enable us to better understand the relationships of surface chemistry, morphologies and structures with the composition of crustal types, including the nature and mobility of volatile species. This will enable estimation of the composition of the mantle from which the crust was derived, and lead to tighter constraints on models for Mercury's origin including the nature and original heliocentric distance of the material from which it formed.Peer reviewe

Two-particle correlations in azimuthal angle and pseudorapidity in inelastic p + p interactions at the CERN Super Proton Synchrotron

Results on two-particle ΔηΔϕ correlations in inelastic p + p interactions at 20, 31, 40, 80, and 158 GeV/c are presented. The measurements were performed using the large acceptance NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The data show structures which can be attributed mainly to effects of resonance decays, momentum conservation, and quantum statistics. The results are compared with the Epos and UrQMD models.ISSN:1434-6044ISSN:1434-605

Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good