A Multistandard Frequency Offset Synchronization Scheme for 802.11n, 802.16d, LTE, and DVB-T/H Systems

Carrier frequency offset (CFO) synchronization is a crucial issue in the implementation of orthogonal frequency division multiplexing (OFDM) systems. Since current technology tends to implement different standards in the same wireless device, a common frequency synchronization structure is desirable. Knowledge of the physical frame and performance and cost system requirements are needed to choose the most suitable scheme. This paper analyzes the performance and FPGA resource requirements of several data-aided (DA) and decision-directed (DD) schemes for four wireless standards: 802.11n, 802.16d, LTE, and DVB-T/H. Performance results of the different methods are shown as BER plots and their resource requirements are evaluated in terms of the number of computations and operators that are needed for each scheme. As a result, a common architecture for the four standards is proposed. It improves the overall performance of the best of the schemes when the four standards are considered while reducing the required resources by 50%

Understanding the neurological implications of acute and long COVID using brain organoids

As early as in the acute phase of the coronavirus disease 2019 about the long-term implications of infection. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), like many other viruses, can trigger chronic disorders that last months or even years. Long COVID, the chronic and persistent disorder lasting more than 12 weeks after the primary infection with SARS-CoV-2, involves a variable number of neurological manifestations, ranging from mild to severe and even fatal. In vitro and in vivo modeling suggest that SARS-CoV-2 infection drives changes within neurons, glia and the brain vasculature. In this Review, we summarize the current understanding of the neuropathology of acute and long COVID, with particular emphasis on the knowledge derived from brain organoid models. We highlight the advantages and main limitations of brain organoids, leveraging their humanoerived origin, their similarity in cellular and tissue architecture to human tissues, and their potential to decipher the pathophysiology of long COVID

Analysis of the Arabidopsis venosa4-0 mutant supports the role of VENOSA4 in dNTP metabolism

Human Sterile alpha motif and histidine-aspartate domain containing protein 1 (SAMHD1) functions as a dNTPase to maintain dNTP pool balance. In eukaryotes, the limiting step in de novo dNTP biosynthesis is catalyzed by RIBONUCLEOTIDE REDUCTASE (RNR). In Arabidopsis, the RNR1 subunit of RNR is encoded by CRINKLED LEAVES 8 (CLS8), and RNR2 by three paralogous genes, including TSO MEANING 'UGLY' IN CHINESE 2 (TSO2). In plants, DIFFERENTIAL DEVELOPMENT OF VASCULAR ASSOCIATED CELLS 1 (DOV1) catalyzes the first step of the de novo biosynthesis of purines. Here, to explore the role of VENOSA4 (VEN4), the most likely Arabidopsis ortholog of human SAMHD1, we studied the ven4‐0 point mutation, whose leaf phenotype was stronger than those of its insertional alleles. Structural predictions suggested that the E249L substitution in the mutated VEN4-0 protein rigidifies its 3D structure. The morphological phenotypes of the ven4, cls8, and dov1 single mutants were similar, and those of the ven4 tso2 and ven4 dov1 double mutants were synergistic. The ven4‐0 mutant had reduced levels of four amino acids related to dNTP biosynthesis, including glutamine and glycine, which are precursors in the de novo purine biosynthesis. Our results reveal high functional conservation between VEN4 and SAMHD1 in dNTP metabolism

H3K4me1 marks DNA regions hypomethylated during aging in human stem and differentiated cells

In differentiated cells, aging is associated with hypermethylation of DNA regions enriched in repressive histone post-translational modifications. However, the chromatin marks associated with changes in DNA methylation in adult stem cells during lifetime are still largely unknown. Here, DNA methylation profiling of mesenchymal stem cells (MSCs) obtained from individuals aged 2 to 92 yr identified 18,735 hypermethylated and 45,407 hypomethylated CpG sites associated with aging. As in differentiated cells, hypermethylated sequences were enriched in chromatin repressive marks. Most importantly, hypomethylated CpG sites were strongly enriched in the active chromatin mark H3K4me1 in stem and differentiated cells, suggesting this is a cell type-independent chromatin signature of DNA hypomethylation during aging. Analysis of scedasticity showed that interindividual variability of DNA methylation increased during aging in MSCs and differentiated cells, providing a new avenue for the identification of DNA methylation changes over time. DNA methylation profiling of genetically identical individuals showed that both the tendency of DNA methylation changes and scedasticity depended on nongenetic as well as genetic factors. Our results indicate that the dynamics of DNA methylation during aging depend on a complex mixture of factors that include the DNA sequence, cell type, and chromatin context involved and that, depending on the locus, the changes can be modulated by genetic and/or external factors

Optimización algorítmica orientada a la implementación en dispositivos reconfigurables de esquemas multiestándar y multiusuario para sincronismo de frecuencia en sistemas de comunicaciones inalámbricas basados en OFDM

Esta Tesis investiga la sincronización de frecuencia para sistemas OFDM, multiestándar OFDM y multiusuario OFDMA. El objetivo de esta Tesis es la de proponer esquemas de sincronización con menor coste computacional que los métodos ya existentes para facilitar su implementación en dispositivos reconfigurables, como son las FPGAs. Por ello, además, se presenta un estudio y una propuesta de metodología usando herramientas de prototipado rápido que sirven para acelerar el proceso de implementación de un sistema DSP. En primer lugar se estudian los efectos de los errores de sincronización de frecuencia sobre las prestaciones de un sistema OFDM y se investigan los diferentes métodos de sincronización, proponiéndose nuevos métodos que reducen la carga computacional sin reducir prestaciones, e incluso, mejorándolas. Para ello se dividen los métodos en captura y seguimiento y estos a su vez se aplican a sistemas de comunicaciones basadas en paquetes, como 802.11g/n ó 802.16d, sistemas basados en transmisión continua, como DVB-T y en sistemas donde se espera gran movilidad, cómo LTE. A continuación, se propone una solución integrada para la sincronización de frecuencia de un sistema multiestándar. Para ello se proponen algoritmos que permitan la reutilización de sus bloques. De esta manera se facilitará una implementación con bajo número de recur- sos. En esta Tesis se propone un seguimiento de frecuencia en un sistema multiestándar que incluya las siguientes tecnologías: 802.11g, 802.16d, DVB-T/H y LTE. La última propuesta algorítmica de esta Tesis se centra en la sincronización en sistemas multiusuario OFDMA para el estándar 802.16e. Aunque existen métodos que obtienen buenas prestaciones, éstos requieren tal cantidad de operaciones que su implementación en una FPGA (la arquitectura destino considerada en esta Tesis) es prácticamente imposible, teniendo además en cuenta que la sincronización es sólo un subsistema de un sistema mucho más grande. En esta Tesis se ha propuesto un método iterativo en el que la estimación y la corrección se realizan de la forma menos costosa posible, algorítmicamente hablando. Este método puede, además, funcionar en todos las posibles modos del 802.16e. Tras el estudio algorítmico de la etapa de sincronización de frecuencia en OFDM y OFDMA, se presenta una metodología de implementación basada en herramientas de prototipado rápido y se explican los pasos a realizar cuando se construye un subsistema de comunicaciones inalámbricas. Se ha elegido esta metodología por ser habitual en el desarrollo de prototipos y porque permite realizar diseños y obtener resultados en un tiempo reducido. Para ello se ha implementado la captura de un CFO para el estándar 802.16d. Este es un ejemplo sencillo pero muy necesario en la sincronización de frecuencia que facilita el mostrar la metodología empleada. ABSTRACT This Thesis focuses on the frequency synchronization problem in OFDM, multistandard OFDM and OFDMA systems. The aim of this Thesis is to propose new synchronization schemes with a reduced computation complexity compared with previous methods from the literature in order to facilitate the implementation in hardware. In particular, implementations targeting reconfigurable hardware (FPGAs). Therefore, methodologies based on rapid prototyping tools that reduce the time and effort required to implement a DSP system are also analyzed and compared. First, the effects of a carrier frequency offset (CFO) are studied and shown. This CFO reduces the performance of the system. Therefore, a comparison of previous and new frequency synchronization methods is performed. The schemes proposed in this Thesis reduce the complexity of the algorithm with no performance penalty. In some cases, they even improve the performance. Acquisition and tracking schemes are evaluated. They are analyzed in terms of packet-based standards, as 802.11g/n or 802.16d, and continuous, as DVB-T, or mobile, as LTE. As a result, an integrated solution for frequency synchronization in a multistandard system is proposed. This system implements the following technologies: 802.11n, 802.16d, LTE, and DVB-T/H. The main goal in this case is that the basic algorithm structure is shared between the different OFDM-based standards, allowing for both, efficient implementations and efficient use of resources on a common baseband processing platform. The last algorithmic proposal in this Thesis focuses in frequency synchronization for multiuser OFDMA systems, as in the 802.16e standard. Although there are methods in the literature that achieve good theoretical performance, they require a very large amount of computations so their FPGA implementation becomes unfeasible. Besides, frequency synchronization is just a subsystem within a transceptor. In this Thesis, an iterative scheme where the estimation and correction of the frequency offsets are performed with a reduced number of computations is proposed. This can be used for all the modes proposed in the 802.16e standard. Once the algorithmic issues of the frequency synchronization problem in OFDM and OFDMA systems have been solved, an implementation methodology using rapid prototyping tools is presented and evaluated. The necessary steps for implementing a wireless communication system with these tools are explained. This implementation methodology has been selected because it is commonly used for system prototyping and it allows to obtain implementation results in short times. In particular, a CFO estimator for the 802.16d standard is implemented. This is a simple but very necessary frequency synchronization that facilitates the comprehension of the design methodology used

Virtual platform for power and security analysis of wireless sensor network

Wireless Sensor Networks (WSNs) include low-power and low-cost devices (nodes) with demanding power requirements (long autonomous lifetime). The nodes have to use the available battery carefully and avoid expensive computations or radio transmissions. Therefore, effective simulation mechanisms that allow the developer to obtain estimations at the early stages of the WSN design, prior to deployment, are necessary. Power consumption is not the only important concern in this design but security is becoming a real problem too, since some WSNs process sensitive data. Thus, it is necessary to ensure that the processed data are tamper-proof. This paper proposes a framework for network simulation and embedded SW performance analysis that focuses not only on time and power estimation but also on two new metrics: the "entropy security-oriented metric" provides information about the security encryption used in WSN transmissions and the "heterogeneity metric" provides information to help avoid "replication attacks". All this information will aid in the whole WSN deployment design, providing useful metrics about power and security.This work was funded by the spanish MICINN through the EUI2010-04255 and TEC2011-28666-C04-02 projects

Impact of glutathione-enriched inactive dry yeast preparations on the stability of terpenes during model wine aging

The impact of the addition of glutathione-enriched Inactive dry yeast preparations (g-IDYs) on the stability of some typical wine terpenes (linalool, α-terpineol, β-citronellol, and nerol) stored under accelerated oxidative conditions was evaluated in model wines. Additionally, the effects of a second type of IDY preparation with a different claim (fermentative nutrient) and the sole addition of commercial glutathione into the model wines were also assessed. Model wines were spiked with the low molecular weight fraction (<3 kDa permeate) isolated from the IDYs, avoiding the interaction of aroma compounds with other yeast components. An exhaustive chemical characterization of both IDY permeates was carried out by using targeted and nontargeted metabolomics approaches using CE-MS and FT-ICR-MS analytical platforms. The findings suggest that the addition of <3 kDa permeate isolated from any of the IDYs employed decreases the loss of typical wine terpenes in model wines submitted to accelerated aging conditions. The g-IDY preparation did indeed release reduced GSH into the model wines, although this compound did not seem exclusively related to the protective effect on some aroma compounds determined in both model wines. The presence of other sulfur-containing compounds from yeast origin in g-IDY, and also the presence of small yeast peptides, such as methionine/tryptophan/tyrosine-containing tripeptide in both types of IDYs, seemed to be related to the antioxidant activity determined in the two permeates and to the minor loss of some terpenes in the model wines spiked with them. © 2014 American Chemical Society.This work was funded by the MINECO (AGL2012-04172-C02-01) and CONSOLIDER INGENIO 2010 (FUN-CFOOD, CSD2007-063, Projects) and by Agrovin, S.A. (I+D 20132446 Contract). J.J.R.B. thanks CSIC for the JAE-doc contract.Peer Reviewe