针对影像处理的快速二维离散余弦转换算法(英文)

由于离散余弦转换在影像处理领域之重要性与日俱增,且消耗许多处理器运算时间,所以众多快速二维离散余弦转换算法不断被发表。该文提出一个应用于JPEG及MPEG图像处理的快速二维8×8离散余弦转换算法,该算法主要运用基本的累加及移位运算,快速评估8×8影像区块的复杂程度,可调整离散余弦转换参数的计算数量。该算法只需花费少量硬件成本,如比较器、加法器、移位器,便可有效降低离散余弦转换运算时间,且在模拟结果显示所提出的算法与传统及整数离散余弦转换相比,可达到较快的运算速度,且在量化系数较大的情况下,可得到更好效果。     

THE ROLE OF HOSPITAL COMPETITION ON TREATMENT EXPENDITURE AND OUTCOME: EVIDENCE FROM STROKE AND CARDIAC TREATMENT IN TAIWAN

This article examines whether market competition affects treatment expenditure and health outcomes of stroke and cardiac treatment in Taiwan. Our measure of treatment expenditure is the hospital expenditure paid at the index admission (short term) and the sum of inpatient and outpatient expenditures paid in the subsequent year (long term). Our measure of health outcome is the probability of death in 1 and 12 months after the hospital's discharge. Our measure of competition follows the method developed by Kessler and McClellan that calculates the Herfindal index based on the predicted patient flows using exogenous variables (e.g., traveling distance to hospitals). Using data of patients hospitalized for new stroke and cardiac treatment between 1997 and 2001 in Taiwan, we find that an increase of market competition results in an insignificant impact on a patient's mortality. In terms of treatment expenditure, our results indicate that hospitals facing more competition incur higher expenditures, either the short‐ or long‐term expenditure. Finally, we find evidence showing that an increase of treatment expenditure at admission is due to a raise of length of stay and treatment intensity per day as well as the usage of expensive equipment. (JEL I11, L13, L41)     

Takacs–Fiksel Method for Stationary Marked Gibbs Point Processes

Abstract. This article studies a method to estimate the parameters governing the distribution of a stationary marked Gibbs point process. This procedure, known as the Takacs–Fiksel method, is based on the estimation of the left and right hand sides of the Georgii–Nguyen–Zessin formula and leads to a family of estimators due to the possible choices of test functions. We propose several examples illustrating the interest and flexibility of this procedure. We also provide sufficient conditions based on the model and the test functions to derive asymptotic properties (consistency and asymptotic normality) of the resulting estimator. The different assumptions are discussed for exponential family models and for a large class of test functions. A short simulation study is proposed to assess the correctness of the methodology and the asymptotic results.     

Central Limit Theorems for the Non‐Parametric Estimation of Time‐Changed Lévy Models

Abstract. Let {Z_t}_{t 0} be a Lévy process with Lévy measure ν and let be a random clock, where g is a non‐negative function and is an ergodic diffusion independent of Z. Time‐changed Lévy models of the form are known to incorporate several important stylized features of asset prices, such as leptokurtic distributions and volatility clustering. In this article, we prove central limit theorems for a type of estimators of the integral parameter β(?):=∫?(x)ν(dx), valid when both the sampling frequency and the observation time‐horizon of the process get larger. Our results combine the long‐run ergodic properties of the diffusion process with the short‐term ergodic properties of the Lévy process Z via central limit theorems for martingale differences. The performance of the estimators are illustrated numerically for Normal Inverse Gaussian process Z and a Cox–Ingersoll–Ross process .     

More than a Theory: A New Map of Social Thought

In this article we revisit two different temporal phases related to the publication of Serge Moscovici's book La Psychanalyse, son image et son public, and we examine two key concepts of the theory: cognitive polyphasia and anchoring. The first phase, initiated by the Durkheimian circle, gives us an opportunity to retrieve traces of the intellectual debate about collective psychology and reconsider this debate in today's light. The second, more recent phase, is inspired by classical and modern research in the field of social representation, and it serves us as a basis for a new hypothesis about anchoring. We suggest that the traditional concept of familiarisation attributed to anchoring can also have an opposite significance: it can transmit and guarantee the non‐familiar and so establish strangeness. Finally, we argue that social representations are more than a simple theory, just like the symbol is always more than what it symbolizes.     

Recession,austerity and gender: A comparison of eight European labour markets

The collapse in GDP brought about by the global economic crisis in 2008 affected female employment less than male employment, whereas austerity has been particularly harsh on women, a gendered impact described in the literature as “he‐cession to sh(e)‐austerity”. This article analyses gendered trends in the labour markets of eight European countries, decomposing quarterly changes in labour participation of women and men and in employment by sector. The “he‐cession to sh(e)‐austerity” scenario is not observed in all countries. Other channels through which austerity policies can jeopardize gender equality and women's rights are identified with reference to a typology of such policies.