Explaining Taxes at the Upper Tail of the Income Distribution: The Role of Utility Interdependence

Optimal tax theory has difficulty rationalizing high marginal tax rates at the upper end of the income distribution. In this paper, I construct a model of optimal income taxation in which agents' preferences are interdependent. I derive a simple expression for optimal taxes that accommodates consumption externalities within Mirrlees (1971) framework. Using this expression, I conduct a positive analysis of taxation: assuming that observed taxes are optimal, I derive analytic expressions for i) a parameter that measures the degree of agents' utility interdependence and ii) a function that quantifies the consumption externality agents of different income impose to society. Using these expressions, I rationalize income taxes in the United States and the United Kingdom for the 1995-2004 period. I show that only a moderate amount of utility interdependence is su±cient for this. My estimations indicate that the progressivity of tax schedules may be driven by corrective considerations.optimal non-linear taxation, relative consumption, utility interdependence, rationalization.

In the quest of macroprudential policy tools

The global financial crisis of late 2008 could not have provided more convincing evidence that price stability is not a sufficient condition for financial stability. In order to attain both, central banks must develop macroprudential instruments in order to prevent the occurrence of systemic risk episodes. For this reason testing the effectiveness of different macroprudential tools and their interaction with monetary policy is crucial. In this paper we explore whether two policy instruments, namely, a capital adequacy ratio (CAR) rule in combination with a Taylor rule may provide a better macroeconomic outcome than a Taylor rule alone. We conduct our analysis by appending a macroeconometric financial block to an otherwise standard semistructural small open economy neokeynesian model for policy analysis estimated for the Mexican economy. Our results show that with the inclusion of the second policy instrument the central bank can obtain substantial gains. Moreover, we find that when the CAR rule is adequately designed the central authority can mitigate output gap shocks of twice the variance than the Taylor rule alone scenario. Thus, under this two rule case the central authority can isolate financial shocks and dampen their effects over macroeconomic variables.macroprudential tools; macroprudential policy; capital adequacy ratio; Taylor rule

Intermittency and the Value of Renewable Energy

A key problem with renewable energy is intermittency. This paper develops a method to quantify the social costs of large-scale renewable energy generation. The method is based on a theoretical model of electricity system operations that allows for endogenous choices of generation capacity investment, reserve operations, and demand-side management. We estimate the model using generator characteristics, solar output, electricity demand, and weather forecasts for an electric utility in southeastern Arizona. The estimated welfare loss associated with a 20% solar photovoltaic mandate is 11% higher than the average cost difference between solar generation and natural gas generation. Unforecastable intermittency yields welfare loss equal to 3% of the average cost of solar. Eliminating a mandate provision requiring a minimum percentage of distributed solar generation increases welfare. With a $21/ton social cost of CO2 this mandate is welfare neutral if solar capacity costs decrease by 65%.

Distributed Linear Precoding and User Selection in Coordinated Multicell Systems

In this manuscript we tackle the problem of semi-distributed user selection with distributed linear precoding for sum rate maximization in multiuser multicell systems. A set of adjacent base stations (BS) form a cluster in order to perform coordinated transmission to cell-edge users, and coordination is carried out through a central processing unit (CU). However, the message exchange between BSs and the CU is limited to scheduling control signaling and no user data or channel state information (CSI) exchange is allowed. In the considered multicell coordinated approach, each BS has its own set of cell-edge users and transmits only to one intended user while interference to non-intended users at other BSs is suppressed by signal steering (precoding). We use two distributed linear precoding schemes, Distributed Zero Forcing (DZF) and Distributed Virtual Signal-to-Interference-plus-Noise Ratio (DVSINR). Considering multiple users per cell and the backhaul limitations, the BSs rely on local CSI to solve the user selection problem. First we investigate how the signal-to-noise-ratio (SNR) regime and the number of antennas at the BSs affect the effective channel gain (the magnitude of the channels after precoding) and its relationship with multiuser diversity. Considering that user selection must be based on the type of implemented precoding, we develop metrics of compatibility (estimations of the effective channel gains) that can be computed from local CSI at each BS and reported to the CU for scheduling decisions. Based on such metrics, we design user selection algorithms that can find a set of users that potentially maximizes the sum rate. Numerical results show the effectiveness of the proposed metrics and algorithms for different configurations of users and antennas at the base stations.Comment: 12 pages, 6 figure

Joint design of RFID reader and tag anti-collision algorithms: a cross-layer approach

This paper investigates the potential interactions between reader and tag anti-collision algorithms of passive RFID (radio frequency identification) systems. Conventionally, reader and tag anti-collision algorithms are designed by assuming that they are independent from each other. In practice, however, readers and tags usually operate in the same frequency band. Therefore, contention between their transmissions can also potentially arise. Furthermore, reader anti-collision policies directly influence the way in which tags are activated, and thus also the way in which they collide when responding to reader’s requests. In view of this and considering the growing numbers of readers and tags, independence of both schemes can not longer be considered as a realistic assumption. This paper partially fills this gap by proposing a new cross-layer framework for the joint evaluation and optimization of reader and tag anticollision algorithms. Furthermore, the paper proposes a new approach, based on a Markov model, which allows capacity and stability analysis of asymmetrical RFID systems (i.e., when readers and tags experience different channel and queuing states). The model captures the dynamics of tag activation and tag detection processes of RFID. It also represents a first step towards a joint design of physical (PHY) and medium access control layers (MAC) of RFID. The results indicate that the proposed approach provides benefits in terms of stability and capacity over conventional solutions even when readers and tags operate in different channels. The results also provide useful guidelines towards the cross-layer design of future RFID platforms

Stability properties of network diversity multiple access with multiple-antenna reception and imperfect collision multiplicity estimation

In NDMA (network diversity multiple access), protocol-controlled retransmissions are used to create a virtual MIMO (multiple-input multiple-output) system, where collisions can be resolved via source separation. By using this retransmission diversity approach for collision resolution, NDMA is the family of random access protocols with the highest potential throughput. However, several issues remain open today in the modeling and design of this type of protocol, particularly in terms of dynamic stable performance and backlog delay. This paper attempts to partially fill this gap by proposing a Markov model for the study of the dynamic-stable performance of a symmetrical and non-blind NDMA protocol assisted by a multiple-antenna receiver. The model is useful in the study of stability aspects in terms of the backlog-user distribution and average backlog delay. It also allows for the investigation of the different states of the system and the transition probabilities between them. Unlike previous works, the proposed approach considers the imperfect estimation of the collision multiplicity, which is a crucial process to the performance of NDMA. The results suggest that NDMA improves not only the throughput performance over previous solutions, but also the average number of backlogged users, the average backlog delay and, in general, the stability of random access protocols. It is also shown that when multiuser detection conditions degrade, ALOHA-type backlog retransmission becomes relevant to the stable operation of NDMA

Low complexity scheduling algorithm for the downlink of distributed antenna systems

In this paper we present a low-complexity user selection algorithm for the downlink of a distributed antenna system (DAS) that achieves an optimum solution for a weighted matching problem. The user selection process is modeled as a linear sum assignment problem (LSAP). The proposed solution consists of two phases. In the first phase, a set of potential users to be scheduled is found by combining two complementary approaches: greedy and minimum-throughput-loss selection. In the second phase, the set of scheduled users is refined by selecting the users that maximize sum throughput. We provide numerical results to confirm the optimality of our user selection algorithm and to compare its performance with existing solutions

Cooperative scheduling for Distributed Antenna Systems

This paper presents a scheduling and link adaptation algorithm for Distributed Antenna Systems (DAS) with Cooperative downlink transmission. The proposed opportunistic scheduler is interference-aware and maximizes the system throughput by controlling the power of the distributed antennas and by optimizing the modulation and coding schemes of each scheduled user. The results show that the proposed algorithm provides considerable throughput gains per resource, more than 200% for high user density. The average number of satisfied users per resource is increased by exploiting user diversity improving the fairness Gini index

HALLAZGOS RADIOLÓGICOS, ULTRASONOGRÁFICOS Y CITOLÓGICOS DEL NÓDULO MAMARIO EN LA CLÍNICA DE MAMA DEL HOSPITAL MATERNO INFANTIL ISSEMyM EN EL PERIODO DEL 1 DE ENERO DEL 2011 AL 31 DE DICIEMBRE DEL 2011.

La mayoría de las lesiones mamarias benignas se desarrollan a partir de alteraciones del proceso fisiológico evolutivo normal de la mama, considerándose aberraciones normales del desarrollo e involución de la mama. La mastalgia cíclica y algunos Nódulos Mamarios pueden aparecer como un desequilibrio hormonal durante la fase cíclica. Los quistes mamarios, las lesiones esclerosantes-fibroticas y la ectasia ductal se desarrollarían durante la fase de involución hasta la menopausi

Frequency-reuse planning of the down-link of distributed antenna systems with maximum-ratio-combining (MRC) receivers

Distributed antenna systems (DAS) have been shown to considerably outperform conventional cellular systems in terms of capacity improvement and interference resilience. However, the influence of frequency reuse planning on the performance of DAS remains relatively unknown. To partially fill this gap, this paper presents a comparative analysis of the down-link of DAS versus conventional cellular systems using different values of frequency reuse factor. The analysis assumes Rayleigh fading channels and it also considers maximum-ratio-combining (MRC) receivers at the user terminals to exploit diversity both in the transmission and reception links. Numerical evaluation of the analytical expressions shows that, in general, for most of the cases DAS can achieve better performance figures than conventional cellular systems using considerably smaller values of frequency reuse factor. Conversely, DAS can significantly improve the throughput (2x-3x) and power consumption (6-10 dB) of conventional systems when using the same frequency reuse factor. An interesting result shows that in some particular cases DAS outperform conventional cellular systems no matter the frequency reuse factor used by the latter one, which indicates an effective capacity gain provided by the combined operation of DAS and MRC receivers