Exact Statistical Characterization of 2×22\times2 Gram Matrices with Arbitrary Variance Profile

This paper is concerned with the statistical properties of the Gram matrix $\mathbf{W}=\mathbf{H}\mathbf{H}^\dagger$, where $\mathbf{H}$ is a $2\times2$ complex central Gaussian matrix whose elements have arbitrary variances. With such arbitrary variance profile, this random matrix model fundamentally departs from classical Wishart models and presents a significant challenge as the classical analytical toolbox no longer directly applies. We derive new exact expressions for the distribution of $\mathbf{W}$ and that of its eigenvalues by means of an explicit parameterization of the group of unitary matrices. Our results yield remarkably simple expressions, which are further leveraged to study the outage data rate of a dual-antenna communication system under different variance profiles.Comment: 6 pages, 1 figure, 1 tabl

The VARying Effect of Foreign Shocks in Central and Eastern Europe

This paper investigates the impact of international shocks – interest rate, commodity price and industrial production shocks – on key macroeconomic variables in ten Central and Eastern European (CEE) countries by using near-VAR models and monthly data from the early 1990s to 2009. In contrast to previous work, the empirical analysis takes explicit account of the possibility of (multiple) structural breaks in the underlying time series. We establish strong evidence of structural breaks, particularly along the years 2007 and 2008, suggesting the very relevant impact of the recent global crisis on CEE economies. Moreover, our results suggest that the way how countries react to world commodity price shocks is related to the underlying economic structure and the credibility of the monetary policy. We also find that some countries like Slovakia and Slovenia – already euro area members – react stronger to foreign industrial production shocks than other countries and that the responses to such shocks are strongly correlated for selected CEE countries. Nevertheless, our results also shed light on substantial differences in responses to foreign interest rate shocks that originate from the US or the euro area.monetary policy; foreign shocks; multiple structural breaks; near-VAR model; CEE economies.

Power Allocation Schemes for Multicell Massive MIMO Systems

This paper investigates the sum-rate gains brought by power allocation strategies in multicell massive multipleinput multiple-output systems, assuming time-division duplex transmission. For both uplink and downlink, we derive tractable expressions for the achievable rate with zero-forcing receivers and precoders respectively. To avoid high complexity joint optimization across the network, we propose a scheduling mechanism for power allocation, where in a single time slot, only cells that do not interfere with each other adjust their transmit powers. Based on this, corresponding transmit power allocation strategies are derived, aimed at maximizing the sum rate per-cell. These schemes are shown to bring considerable gains over equal power allocation for practical antenna configurations (e.g., up to a few hundred). However, with fixed number of users (N), these gains diminish as M turns to infinity, and equal power allocation becomes optimal. A different conclusion is drawn for the case where both M and N grow large together, in which case: (i) improved rates are achieved as M grows with fixed M/N ratio, and (ii) the relative gains over the equal power allocation diminish as M/N grows. Moreover, we also provide applicable values of M/N under an acceptable power allocation gain threshold, which can be used as to determine when the proposed power allocation schemes yield appreciable gains, and when they do not. From the network point of view, the proposed scheduling approach can achieve almost the same performance as the joint power allocation after one scheduling round, with much reduced complexity

Analysis and Design of Multiple-Antenna Cognitive Radios with Multiple Primary User Signals

We consider multiple-antenna signal detection of primary user transmission signals by a secondary user receiver in cognitive radio networks. The optimal detector is analyzed for the scenario where the number of primary user signals is no less than the number of receive antennas at the secondary user. We first derive exact expressions for the moments of the generalized likelihood ratio test (GLRT) statistic, yielding approximations for the false alarm and detection probabilities. We then show that the normalized GLRT statistic converges in distribution to a Gaussian random variable when the number of antennas and observations grow large at the same rate. Further, using results from large random matrix theory, we derive expressions to compute the detection probability without explicit knowledge of the channel, and then particularize these expressions for two scenarios of practical interest: 1) a single primary user sending spatially multiplexed signals, and 2) multiple spatially distributed primary users. Our analytical results are finally used to obtain simple design rules for the signal detection threshold.Comment: Revised version (14 pages). Change in titl

FOXE1 mutation screening in a case with Cleft Lip, Hypothyroidism, and Thyroid Carcinoma: A new syndrome?

A 26-year-old woman is referred to the Internal Medicine consultation due to increases in laboratory studies associated with Papillary Thyroid Carcinoma (PTC) that was confirmed by histopathological studies. Her clinical history revealed that, at 3 months of age, she was successfully treated with surgery for cleft lip (CL) and at the age of 24 years was diagnosed with hypothyroidism. Single nucleotide polymorphisms (SNPs) in FOXE1 and its promoter regions have been associated with various etiologies related to the thyroid, including orofacial clefting, specially cleft palate (CP) and CL, hypothyroidism (HT), and thyroid cancer. The association of CL, HT, and PTC might be component of a new syndrome; however FOXE1 coding region, which has been involved with these entities, has not exhibited mutations or SNPs. Further study of other genes may help in better characterization of the possible syndrome

Pattern of Amino Acid Substitutions in Transmembrane Domains of β-Barrel Membrane Proteins for Detecting Remote Homologs in Bacteria and Mitochondria

-barrel membrane proteins play an important role in controlling the exchange and transport of ions and organic molecules across bacterial and mitochondrial outer membranes. They are also major regulators of apoptosis and are important determinants of bacterial virulence. In contrast to -helical membrane proteins, their evolutionary pattern of residue substitutions has not been quantified, and there are no scoring matrices appropriate for their detection through sequence alignment. Using a Bayesian Monte Carlo estimator, we have calculated the instantaneous substitution rates of transmembrane domains of bacterial -barrel membrane proteins. The scoring matrices constructed from the estimated rates, called bbTM for -barrel Transmembrane Matrices, improve significantly the sensitivity in detecting homologs of -barrel membrane proteins, while avoiding erroneous selection of both soluble proteins and other membrane proteins of similar composition. The estimated evolutionary patterns are general and can detect -barrel membrane proteins very remote from those used for substitution rate estimation. Furthermore, despite the separation of 2–3 billion years since the proto-mitochondrion entered the proto-eukaryotic cell, mitochondria outer membrane proteins in eukaryotes can also be detected accurately using these scoring matrices derived from bacteria. This is consistent with the suggestion that there is no eukaryote-specific signals for translocation. With these matrices, remote homologs of -barrel membrane proteins with known structures can be reliably detected at genome scale, allowing construction of high quality structural models of their transmembrane domains, at the rate of 131 structures per template protein. The scoring matrices will be useful for identification, classification, and functional inference of membrane proteins from genome and metagenome sequencing projects. The estimated substitution pattern will also help to identify key elements important for the structural and functional integrity of -barrel membrane proteins, and will aid in the design of mutagenesis studies

CONOCIMIENTOS QUE TIENEN LAS MUJERES ACERCA DEL CLIMATERIO Y USO DE LA TERAPIA DE REEMPLAZO HORMONAL.

El climaterio es un acontecimiento normal que se presenta de manera evolutiva en la vida de la mujer, que se presenta este periodo comprende 10 a 15 de duración en el cual se presentan profundos cambios psicológicos y fisiológicos, y uno de los cambios más transcendentes es la pérdida de la capacidad reproductiva. La menopausia se caracteriza como la última menstruación de la mujer y se establece pasando un año ininterrumpido de amenorrea, en México la edad media en que aparece la menopausia varía de 47 a 49 años. Aunando a este periodo se ha observado padecimientos crónico-degenerativos como son: la osteoporosis y la enfermedad cardiovascular asociado a la posmenopausia. En las últimas tres décadas se ha avanzado en la mejorar de la salud de la mujer brindándole uso de la terapia hormonal de reemplazo (THR); que coadyuva a disminuir la sintomatología en general, así como la osteoporosis y disminuir el riesgo cardiovascular por hipoestrogenismo, mejorar la condición mental y por consecuencia su calidad de vida