Sequential decisions in the college admissions problem

This paper models a contractual process by a sequential mechanism, which mimics matching procedures for many-to-one real-life matching problems. In this framework, we provide a family of mechanisms implementing the student-optimal matching in Subgame Perfect Equilibrium (SPE).Alcalde’s work is partially supported by the Institut Valencia` d’Investigacions Econo`miques and the Spanish Ministerio de Educacio´n y Cultura under project BEC 2001-0535. Romero-Medina acknowledges financial support from the Spanish Ministerio de Educacio´n y Cultura under project BCE-2002-02194 and Comunidad de Madrid under project 02303.Publicad

Sequential Decisions in the College Admissions Problem

This paper studies sequential mechanisms which mimic matching prodedures for many-to-one real life matching markets. We provide a family of mechanisms implementing the student´optimal allocation in Subgame Perfect Equilibriu

Simple Mechanisms to Implement the Core of College Admisions Problems

This paper analyzes simple mechanisms implementing (subselections of) the core correspondence of matching markets. We provide a sequential mechanism which mimics a matching procedure for many-to-one real life matching markets. We show that only core allocations should be attained when agents act strategically when faced with this mechanism. We also provide a second mechanism to implement the core correspondence in Subgame Perfect Equilibrium.Alcalde’s work is partially supported by the Institut Valencia d’Investigacions Econòmiques and DGICYT under project PB 97–0131. Romero–Medina acknowledges financial support from the Instituto de Estudios Fiscales and DGICYT under project PB 92–0590.Publicad

Short-timescale Fluctuations in the Difference Light Curves of QSO 0957+561A,B: Microlensing or Noise?

From optical R band data of the double quasar QSO 0957+561A,B, we made two new difference light curves (about 330 days of overlap between the time-shifted light curve for the A image and the magnitude-shifted light curve for the B image). We observed noisy behaviours around the zero line and no short-timescale events (with a duration of months), where the term event refers to a prominent feature that may be due to microlensing or another source of variability. Only one event lasting two weeks and rising - 33 mmag was found. Measured constraints on the possible microlensing variability can be used to obtain information on the granularity of the dark matter in the main lensing galaxy and the size of the source. In addition, one can also test the ability of the observational noise to cause the rms averages and the local features of the difference signals. We focused on this last issue. The combined photometries were related to a process consisting of an intrinsic signal plus a Gaussian observational noise. The intrinsic signal has been assumed to be either a smooth function (polynomial) or a smooth function plus a stationary noise process or a correlated stationary process. Using these three pictures without microlensing, we derived some models totally consistent with the observations. We finally discussed the sensitivity of our telescope (at Teide Observatory) to several classes of microlensing variability.Comment: MNRAS, in press (LaTeX, 14 pages, 22 eps figures

Path integral approach to the full Dicke model with dipole-dipole interaction

We consider the full Dicke spin-boson model composed by a single bosonic mode and an ensemble of $N$ identical two-level atoms with different couplings for the resonant and anti-resonant interaction terms, and incorporate a dipole-dipole interaction between the atoms. Assuming that the system is in thermal equilibrium with a reservoir at temperature $\beta^{-1}$, we compute the free energy in the thermodynamic limit $N\rightarrow\infty$ in the saddle-point approximation to the path integral and determine the critical temperature for the superradiant phase transition. In the zero temperature limit, we recover the critical coupling of the quantum phase transition, presented in the literature

X-ray characterization of BUSARD chip: A HV-SOI monolithic particle detector with pixel sensors under the buried oxide

This work presents the design of BUSARD, an application specific integrated circuit (ASIC) for the detection of ionizing particles. The ASIC is a monolithic active pixel sensor which has been fabricated in a High-Voltage Silicon-On-Insulator (HV-SOI) process that allows the fabrication of a buried N+ diffusion below the Buried OXide (BOX) as a standard processing step. The first version of the chip, BUSARD-A, takes advantage of this buried diffusion as an ionizing particle sensor. It includes a small array of 13×13 pixels, with a pitch of 80 μm, and each pixel has one buried diffusion with a charge amplifier, discriminator with offset tuning and digital processing. The detector has several operation modes including particle counting and Time-over-Threshold (ToT). An initial X-ray characterization of the detector was carried out, obtaining several pulse height and ToT spectra, which then were used to perform the energy calibration of the device. The Molybdenum $_{α}$ emission was measured with a standard deviation of 127 e$^{-}$ of ENC by using the analog pulse output, and with 276 e$^{-}$ of ENC by using the ToT digital output. The resolution in ToT mode is dominated by the pixel-to-pixel variation

A Large Brightness Enhancement of the QSO 0957+561 A Component

We report an increase of more than 0.2 mag in the optical brightness of the leading image (A) of the gravitational lens Q0957+561, detected during the 09/2000 -- 06/2001 monitoring campaign (2001 observing season). The brightening is similar to or even greater than the largest change ever detected during the 20 years of monitoring of this system. We discuss two different provisional explanations to this event: intrinsic source variability or microlensing (either short timescale microlensing or cessation of the historical microlensing). An exhaustive photometric monitoring of Q0957+561 is needed until summer of 2002 and during 2003 to discriminate between these possibilities.Comment: 13 pages including 3 figures and 1 table. Accepted for publication in ApJ Let