Nuclear relocation of Kss1 contributes to the specificity of the mating response.

Mitogen Activated Protein Kinases (MAPK) play a central role in transducing extra-cellular signals into defined biological responses. These enzymes, conserved in all eukaryotes, exert their function via the phosphorylation of numerous substrates located throughout the cell and by inducing a complex transcriptional program. The partitioning of their activity between the cytoplasm and the nucleus is thus central to their function. Budding yeast serves as a powerful system to understand the regulation of these fundamental biological phenomena. Under vegetative growth, the MAPK Kss1 is enriched in the nucleus of the cells. Stimulation with mating pheromone results in a rapid relocation of the protein in the cytoplasm. Activity of either Fus3 or Kss1 in the mating pathway is sufficient to drive this change in location by disassembling the complex formed between Kss1, Ste12 and Dig1. Artificial enrichment of the MAPK Kss1 in the nucleus in presence of mating pheromone alters the transcriptional response of the cells and induces a cell-cycle arrest in absence of Fus3 and Far1

Synchronization in all-digital QAM receivers

The recent advance in Field Programmable Gate Array (FPGA) technology has been largely embraced by the communication industry, which views this technology as an effective and economical alternative to the design of Application Specific Integrated Circuits (ASICs). The primary reasons for switching to FPGAs are lower development and non-recurring engineering costs, the flexibility to design to a preliminary standard and adapt the design as the standard evolves, as well as the option of performing software updates in the field. A sector with strong interest in FPGAs is the coaxial cable TV/Internet distribution industry. The creation of soft preliminary standards by the standards organization governing the industry has been the main catalyst for the massive adoption of FPGAs by small to medium size companies, which see this technology as an opportunity to compete in this open market. Both the circuit speed and the economy of FPGA technology depend upon using algorithms that map efficiently into its fabric. Often it is prudent to sacrifice performance to improve either clock speed or economy when developing with FPGAs. The purpose of this research is to both revise and devise synchronization algorithms / structures for cable digital receivers that are to be implemented in FPGA. The main communication scheme used by the coaxial cable distribution industry is digital Quadrature Amplitude Modulation (QAM). The problem of synchronizing to the QAM signal in the receiver is not a new topic and several synchronization-related circuits, which were devised with ASICs implementation in mind, can be found in the open literature. Of interest in this thesis is the non-data-aided digital timing synchronizer that was proposed by D'Andrea to recover timing with no knowledge of the transmitted data. Accurate timing estimation was achieved by reshaping the received signal with a prefilter prior to estimating the timing. A problem with D'Andrea's synchronizer is that the prefilter for reshaping the signal is a relatively long Finite Impulse Response (FIR) filter, whose implementation requires a large number of multipliers. This may not have been an issue with ASICs in as much as the number of hardwired multipliers on a chip is not limited as it is in an FPGA chip. One contribution in this research is to propose an alternative to D'Andrea's synchronizer by replacing the long FIR filter with two single-pole Infinite Impulse Response (IIR) filters that are directly placed inside the timing recovery loop. This novel architecture, which drastically reduces the number of multipliers, is well suited for FPGA implementation. Non-data-aided feedforward synchronizers, which use the same prefilter as D'Andrea's synchronizer, have been receiving significant attention in recent years. Detailed performance analysis for these synchronizers can be found in the open literature. These synchronizers have the advantage of using a feedfordward structure rather than a feedback structure, as it is the case in D'Andrea's synchronizer, to estimate the timing. While D'Andrea's synchronizer has an advantage in performance over a non-data-aided feedforward synchronizer, this has not been reported in the literature. In this thesis a second contribution consists of thoroughly analyzing the steady state timing jitter in D'Andrea synchronizer by deriving a closed-form expression for the noise power spectrum and a simple equation to estimate the timing jitter variance. A third contribution is a novel low-complexity and fast acquisition coherent detector for the detection of Quadrature Phase Shift Keying (QPSK) (i.e., 4-QAM) symbols. This detector performs carrier phase synchronization much faster than a conventional coherent detector. The acquisition time is comparable to that of a differential detector. The fast acquisition comes at the expense of phase jitter, and the end result is a 1 dB performance loss over theoretical coherent detection. This detector can be used in place of the differential detector with no economic penalty. Doing so yields a performance advantage of about 2 dB over differential detection

Mode Orthogonality in Chirowaveguides

In this paper, we derive the orthogonality relations for modes supported by a general cylindrical chirowaveguide. As introduced in our earlier work, a chirowaveguide is a cylindrical waveguide filled with chiral or optically active materials. As in conventional waveguides, the orthogonality relations reported here can be used to expand an arbitrary E or H field within a chirowaveguide in terms of a complete set of mutually orthogonal modes in the waveguide

Single-particle imaging of stress-promoters induction reveals the interplay between MAPK signaling, chromatin and transcription factors.

Precise regulation of gene expression in response to environmental changes is crucial for cell survival, adaptation and proliferation. In eukaryotic cells, extracellular signal integration is often carried out by Mitogen-Activated Protein Kinases (MAPK). Despite a robust MAPK signaling activity, downstream gene expression can display a great variability between single cells. Using a live mRNA reporter, here we monitor the dynamics of transcription in Saccharomyces cerevisiae upon hyper-osmotic shock. We find that the transient activity of the MAPK Hog1 opens a temporal window where stress-response genes can be activated. We show that the first minutes of Hog1 activity are essential to control the activation of a promoter. Chromatin repression on a locus slows down this transition and contributes to the variability in gene expression, while binding of transcription factors increases the level of transcription. However, soon after Hog1 activity peaks, negative regulators promote chromatin closure of the locus and transcription progressively stops

The Theory of Chirowaveguides

Recently a new type of guided-wave structure, named chirowaveguide was suggested by the authors. The chirowaveguides consist of cylindrical waveguides filled with homogeneous isotropic chiral materials. Due to the electromagnetic chirality of the material inside the waveguide, several important features area associated with this type of guided-wave structure. In this paper, the theory of chirowaveguides is discussed and their salient features are analyzed. It is show that the Helmhotz equations for the longitudinal components of electric and magnetic fields in chirowaveguides are always coupled and consequently, in these waveguides individual transverse electric (TE), transverse magnetic (TM), or transverse electromagnetic (TEM) modes cannot be supported. As an illustrative example, the parallel-plate chirowaveguide is analyzed in detail and the corresponding dispersion relations, cut-off frequencies, propagating and evanescent modes are obtained. In the dispersion (Brillouin) diagram for a chirowaveguide, three regions are identified: the fast-fast-wave region, the fast-slow-wave region and the slow-slow-wave region. For each of these regions the electromagnetic field components in a parallel-plat chirowaveguide are analyzed and the electric field components are plotted. Potential applications of chirowaveguides in integrated optical devices, communication systems, and printed circuit antennas are mentioned

Wage determinants in Spain (1980-2000)

This paper provides evidence about the nominal wage determinants in Spain during the period 1980-2000. We estimate a wage equation, using time series analysis applying an error correction mechanism. Our aim is to analyse the extent to which the evolution of wages is influenced by the unemployment, prices and productivity. The results reveal that the unemployment rate has no effect on the evolution of nominal wages. The variable that explains the evolution of nominal wages in the long term is prices, showing slightly inflationary behaviour. In the short term, wages are explained by their past values, reflecting a nominal inertia

Beyond the Critique of Rights: The Puerto Rico Legal Project and Civil Rights Litigation in America\u27s Colony

Long skeptical of the ability of rights to advance oppressed groups’ political goals, Critical Legal Studies (CLS) scholars might consider a U.S. territory like Puerto Rico and ask, “What good are rights when you live in a colony?” In this Note, I will argue that CLS’s critique of rights, though compelling in the abstract, falters in the political and historical context of Puerto Rico. Although it may appear that rights have failed Puerto Ricans, rights talk has historically provided a framework for effective organizing and community action. Building on the work of Critical Race Theory and LatCrit scholars, this Note counters the CLS intuition that rights talk lacks value by focusing on the origins and development of the Puerto Rico Legal Project, an understudied but critical force for community development and legal advocacy on the island that was founded in response to severe political repression during the late 1970s and early 1980s. This Note draws on original interviews with Puerto Rican and U.S. lawyers and community activists to reveal fissures in the critique of rights and to propose certain revisions to the theory. By concentrating on the entitlements that rights are thought to provide, CLS’s critique of rights ignores the power of rights discourse to organize marginalized communities. The critique of rights also overlooks the value of the collective efforts that go into articulating a particular community’s aspirations through rights talk, efforts which can be empowering and help spur further political action. By analyzing twentieth-century Puerto Rican legal and political history and the Puerto Rico Legal Project, I demonstrate the value (and limits) of rights in a colonized nation

Coupled-mode theory for chirowaveguide

In this paper, electromagnetic wave propagation and mode coupling in a chirowaveguide are treated using the coupled-mode theory. A chirowaveguide, as defined in our previous work, is a conventional cylindrical waveguide filled with homogeneous chiral materials. A set of coupled linear differential equations is derived for various mode amplitudes in the waveguide. We then show that, in any single chirowaveguide, owing to the handed properties of chiral materials filling the waveguide, energy coupling occurs from one mode to the other. We also demonstrate that in a parallel-plate chirowaveguide a TE mode can be completely converted into a TM mode and vice versa as they propagate in the guide. Thus a chirowaveguide can indeed be used as a mode converter. Selected results are compared with those reported in the literature. Applications of such mode coupling in the design of novel microwave, millimeterwave, and optical devices and components are mentioned

When Engagement in Course-Related Social Media Leads to Better Course Self-Efficacy

Learners nowadays bring social media (SM) user’s knowledge to the classrooms with them. Many teachers (researchers, professors, instructors, and people in charge of the learning organizations in general) have to deal with the fact that individuals 1) sometimes adopt a mute behavior in classroom and 2) duplicate their offline social networks in SM spaces. Engagement in course-related SM groups leads to engagement into the course subject, that improves self-efficacy of the learners. This paper seeks to find out why individuals engage in course-related SM groups and how the SM engagement of silent students can mediate their self-efficacy. Results show that experiencing eudaimonism as an emotion and state of flow, positively affects the engagement in course-related SM groups. SM engagement positively affects students’ self-efficacy and mediates the negative effect of selective mutism. This research has implications for educational institutions as well as researchers in the e-learning fields